We generally consider climate changes as taking place on the scale of hundreds or even thousands of years. However, since the early 1990s, a radical shift in the scientific understanding of Earth's climate history has occurred. We now know that that major regional and global climate shifts have occurred in just a few decades or even a single year. The most recent of these shifts occurred just 8200 years ago. If an abrupt climate change of similar magnitude happened today, it would have severe consequences for humans and natural ecosystems. Although scientists consider an abrupt climate change unlikely in the next 100 years, their understanding of the phenomena is still a work-in-progress, and such a change could be triggered instantly by natural processes or by human-caused global warming with little warning.
The National Academy of Sciences--the board of scientists established by Congress in 1863 to advise the federal government on scientific matters--compiled a comprehensive report in 2002 entitled, Abrupt Climate Change: Inevitable Surprises. The 244-page report, which contains over 500 references, was written by a team of 59 of the top researchers in climate, and represents the most authoritative source of information about abrupt climate change available. Most of the material that follows was taken from this report.
The Greenland Ice Sheet: The Key to Understanding Earth's Climate Record
Ice cores hold an amazingly detailed record of Earth's climate. Each year, snow falling on glacial areas accumulates, piling on top of thousands of years of past snow, compressing the snow into yearly layers of ice, like rings inside a tree trunk. Preserved in the ice are tiny bubbles of ancient air that tell us the composition of the atmosphere at that time. The amount of dust in the snow tells us how windy the climate was. The thickness of the layer tells how much precipitation fell that year. Most importantly, the amount of the "heavy" isotope of oxygen, 18O, lets us infer the average atmospheric temperature, since water vapor with "heavy" 18O molecules condenses out of clouds more readily at cold temperatures.
Accessing this treasure-trove of climatic information is a huge undertaking--cores of ice must be drilled miles deep in some of the most inhospitable places on Earth. In 1989 the National Science Foundation funded the $25 million Greenland Ice Sheet Project II (GISP2) to drill an ice core through the entire two mile depth of the Greenland ice sheet. At the same time, a separate European project (GRIP), drilled through the ice just 20 miles away, providing a crucial independent check of the GISP2 data. By 1993, both the GRIP and GISP2 drills had hit bedrock, and two miles of ice cores, preserving 110,000 years of climate history in year-by-year layers, were taken to laboratories for analysis.
What the scientists found was surprising and unnerving. They had known from previous ice core and ocean sediment core data that Earth's climate had fluctuated significantly in the past. But what astonished them was the rapidity with which these changes occurred.
Ocean and lake sediment data from places such as California, Venezuela, and Antarctica have confirmed that these sudden climate changes affected not just Greenland, but the entire world. During the past 110,000 years, there have been at least 20 such abrupt climate changes. Only one period of stable climate has existed during the past 110,000 years--the 11,000 years of modern climate (the "Holocene" era). "Normal" climate for Earth is the climate of sudden extreme jumps--like a light switch flicking on and off.
Figure 1. Average Yearly Temperatures in Greenland over the past 100,000 Years as inferred from Oxygen isotope analysis of the GISP2 Greenland ice core.
Source: Cuffey, K.M., and G.D. Clow, "Temperature, accumulation, and ice sheet elevation in central Greenland throughout the last deglacial transition", Journal of Geophysical Research, 102, 383-396, 1997.
As seen in Figure 1, the ice core record showed frequent sudden warmings and coolings of 15° F (8°C) or more. Many of these changes happened in less than 10 years. In one case 11,600 years ago, when Earth emerged from the final phase of the most recent ice age (an event called the Younger Dryas), the Greenland ice core data showed that a 15°F (8°C) warming occurred in less than a decade, accompanied by a doubling of snow accumulation in 3 years. Most of this doubling occurred in a single year.
What causes abrupt climate change?
Current theories on the cause of abrupt climatic change focus on sudden shut downs and start-ups of the Meridional Overturning Circulation (MOC) (also referred to as the thermohaline circulation), which is a global network of density-driven ocean currents. The Meridional Overturning Circulation transports a tremendous amount of heat northward, keeping the North Atlantic and much of Europe up to 9�F (5�C) warmer, particularly in the winter. A sudden shut down of this current would have a ripple effect throughout the ocean-atmosphere system, forcing worldwide changes in ocean currents, and in the path of the atmospheric jet stream. Studies of North Atlantic Ocean sediments have revealed that the Meridional Overturning Circulation has shut down many times in the past, and that many of these shut downs coincide with the abrupt climate change events noted in the Greenland ice cores.
How does one shut down the Meridional Overturning Circulation ? First, one must examine the MOC itself. The MOC, or Great Ocean Conveyor Belt (Figure 2), is a system of interconnected ocean currents that girdle the planet.
At the surface, warmer ocean currents (shown here in orange) are driven by the winds, and so move parallel to the wind direction, except where continental land masses block the way. Water can also move vertically in the ocean. High density water sinks, and low density water rises. Salty water is more dense than fresh water, and cold water is more dense than warm water, so that wherever we find cold, salty water, it tends to sink. Colder currents (shown here in blue) are deeper and have higher salinity.
In the tropical Atlantic, the sun's heat evaporates large amounts of water, creating relatively warm, salty ocean water. This warm, salty water flows westward toward North America, then up the East Coast of the U.S., then northeastward toward Europe, forming the mighty Gulf Stream current. As this warm, salty water reaches the ocean regions on either side of Greenland, cold winds blowing off of Canada and Greenland cool the water substantially (in Figure 2, these regions are marked with white circles labeled, "Heat release to the atmosphere.") These cool, salty waters are now very dense compared to the surrounding waters, and sink to the bottom of the ocean. Thus, the oceanic areas by Greenland where this sinking occurs are called "deep-water formation areas". This North Atlantic deep water flows southward toward Antarctica, eventually making it all the way to the Pacific Ocean, where it rises back to the surface to complete the Great Ocean Conveyor Belt. It takes about 1000 years for the water to make a complete circuit around the globe.
Since the Great Ocean Conveyor Belt is driven in part by differences in ocean water density, if one can pump enough fresh water into the ocean in the key areas on either side of Greenland where the Gulf Stream waters cool and sink, this will lower the ocean's salinity (and therefore its density) enough so that the waters can no longer sink. As a result, the Atlantic conveyor belt and Gulf Stream current would shut down in just a few years, dramatically altering the climate.
How much fresh water is needed to shut down the MOC?
It is unknown precisely how much fresh water is needed to shut down the MOC. Scientists are fairly certain that the last two abrupt coolings seen the Greenland ice core, the "Younger Dryas" event and the "8200 years before present" event (Figure 1), both occurred when huge North American glacial melt-water lakes flooded down the St. Lawrence River into the North Atlantic when the ice dams restraining the lakes broke. The sudden addition of low-density fresh water presumably partially or totally stopped the sinking of ocean waters in the North Atlantic, slowing or completely stopping the Meridional Overturning Circulation. Once the fresh water got into the North Atlantic, it stayed, puddling on top of the ocean and freezing in winter. The Meridional Overturning Circulation stayed shut off for about 1100 years during the Younger Dryas event, then suddenly restarted, for reasons scientists don't understand. Current computer models of the climate cannot reproduce the observed sudden shut-down or start-up of the Meridional Overturning Circulation at the beginning and end of the Younger Dryas period.
Other sudden shut downs of the Meridional Overturning Circulation observed in ice core and ocean sediment records are not thought to be due to sudden melt-water floods into the North Atlantic. These events may have happened simply because Earth's climate system is chaotic, or perhaps because some critical threshold was crossed when increases in precipitation, river run-off, and ice melt put enough fresh water into the ocean to shut down the Meridional Overturning Circulation.
How likely is it that global warming will trigger abrupt climate change?
Global warming will increase precipitation, river run-off, melting of the Greenland ice sheet, and melting of polar sea ice, all of which will increase the amount of fresh water flowing into the critical deep-water formation areas by Greenland. In the 2007 IPCC Fourth Assessment Report Summary for Policymakers it states that, based on current model simulations, it is very likely (90-99% confidence) that the meridional overturning circulation (MOC) of the Atlantic Ocean will slow down during the 21st century. It also confirms the scientific consensus that is very unlikely the MOC will undergo a large abrupt transition during this century. Today's science is such that any long-term assessments of the MOC cannot be made with confidence.
How would the climate change if the Meridional overturning circulation shut down?
A shut down of the Meridional overturning circulation would suddenly decrease the amount of heat in the North Atlantic, leading to much colder temperatures in Europe and North America. A 2003 report prepared for the Department of Defense outlines what would happen if an abrupt climatic change similar to the 8200 years before present event were to recur today:
# Annual average temperatures would drop up to 5° F in North America, and up to 6° F in northern Europe. This is not sufficient to trigger an ice age, which requires about a 10° F drop in temperature world-wide, but could bring about conditions like experienced in 1816--the famed "year without a summer". In that year, volcanic ash from the mighty Tambora volcanic eruption in Indonesia blocked the sun's rays, significantly cooling the globe. Snow fell in New England in June, and killing frosts in July and August caused widespread crop failures and famine in New England and northern Europe.
# Annual average temperatures would warm up to 4° F in many areas of the Southern Hemisphere.
# Multi-year droughts in regions unaccustomed to drought would affect critical agricultural and water resource regions world-wide, greatly straining food and water supplies.
# Winter storms and winds would strengthen over North America and Europe.
Dr. Wally Broecker of Columbia University, the scientist who first pointed out the link between the Atlantic's conveyor circulation and abrupt climate change, wrote a letter in March 2004 to Science magazine, accusing the authors of the study of making exaggerated claims that "only intensify the existing polarization over global warming". Broecker argued that a global-warming induced abrupt climate change is not likely to occur until 100 years or so into the future, by which time Earth's temperature will have warmed sufficiently to offset much of the abrupt cooling a Meridional overturning circulation shut down would trigger. Broecker added: "What is needed is not more words but rather a means to shut down carbon dioxide emissions." The authors of the study defend their scenario thusly: "We have created a climate change scenario that although not the likely, is plausible, and would challenge United States national security in ways that should be considered immediately".
On the freezing of the UK and Europe
The possibility of the freezing of the UK and Europe will be determined by a "tug-of-war" of sorts, between the amount of greenhouse gases and the speed with which the MOC slows down. Greenhouse gases may have more of an impact than a slowing of the MOC, simply because they are more abundant today than ever in the earth's record. (CO2 levels were at 380 ppm as of 2007, and were never above 300 ppm during the 400,000 years studied in Antarctic ice cores).
Ocean experts see the MOC as having three levels: "faster", "slower", or "off." A 2005 comparison of eleven climate models showed that the MOC will likely be slowed by 10-50%, however, because the levels of carbon dioxide are so elevated, any cooling produced by the MOC slowing would be modest because the greenhouse gases would more than compensate. As a result, a net warming is still shown by these models for the UK and surrounding countries. Improving our measurements to monitor the MOC will allow for better predictions and reduce uncertainty of the amount of warming or cooling these areas of northern Europe will encounter.
What is being done about abrupt climate change?
The immediate obvious needs are for accurate, long-term measurements of the temperature, salinity, and flow rates of the major ocean currents in the North Atlantic Ocean. An expedition set sail from Great Britain on Feb. 13 2004, to provide just that. The voyage was part of a joint US/UK research project called Rapid Climate Change, which began in 2001. In the U.S., Senator Susan Collins (R-Maine) sponsored bill S.1164 to authorize $60 million for the National Oceanic and Atmospheric Administration (NOAA) to study abrupt climate change. On March 9, 2004, the Senate Commerce Committee approved the bill. It defines abrupt climate change as "a change in the climate that occurs so rapidly or unexpectedly that human or natural systems have difficulty adapting to the climate as changed." The bill would create a research program within NOAA's Office of Oceanic and Atmospheric Research to determine what causes sudden climate changes and using computer models to predict climate change events. This bill did not pass, and there is little chance for revival. The NTSC Joint Subcommittee On Ocean Science and Technology authored an Ocean Research Priorities Plan in January 2007, providing five key elements for reducing our vulnerability to abrupt climate change. These include: daily monitoring of ocean currents, temperature, and carbon, now-casting, model development, past-climate-change reconstructions, and additional climate-impact assessments.
Conclusion
The historical records shows us that abrupt climate change is not only possible--it is the normal state of affairs. The present warm, stable climate is a rare anomaly. It behooves us to learn as much as we can about the climate system so that we may be able to predict when the next abrupt shift in climate will come. Until we know better when this might happen, it would be wise to stop pouring so much carbon dioxide into the air. A nasty surprise might be lurking just around the corner. In the words of Dr. Wally Broecker, "the climate system is an angry beast, and we are poking it."
For further reading:
IPCC 4th Assessment, Chapter 5: Observations: Oceanic Climate Change and Sea Level 2007.
Who ya gonna call? RealClimate.org post by Gavin Schmidt and Michael Mann, August, 2007.
NASA's "A Chilling Possibility" press release, March 2004.
Abrupt Climate Change: Should we be worried?" Analysis by Woods Hole Oceanographical Institute, January 2003.
The Great Climate Flip-flop, a 1998 Atlantic Monthly article.
Abrupt climate change, a report prepared by Global Business Network (GBN) for the Department of Defense, October 2003.
The Two-Mile Time Machine : Ice Cores, Abrupt Climate Change, and Our Future, by Dr. Richard Alley, 2001. An excellent book on the Greenland ice cores findings.
The Day After Tomorrow: Could it really happen?
Monday, September 15, 2008
Thermal Conductivity
In physics, thermal conductivity, k, is the property of a material that indicates its ability to conduct heat. It appears primarily in Fourier's Law for heat conduction.
First, we define heat conduction by the formula:
H=\frac{\Delta Q}{\Delta t}=k\times A\times\frac{\Delta T}{x}
where \frac{\Delta Q}{\Delta t} is the rate of heat flow, k is the thermal conductivity, A is the total surface area of conducting surface, ΔT is temperature difference and x is the thickness of conducting surface separating the 2 temperatures.
Thus, rearranging the equation gives thermal conductivity,
k=\frac{\Delta Q}{\Delta t}\times\frac{1}{A}\times\frac{x}{\Delta T}
(Note: \frac{\Delta T}{x} is the temperature gradient)
In other words, it is defined as the quantity of heat, ΔQ, transmitted during time Δt through a thickness x, in a direction normal to a surface of area A, due to a temperature difference ΔT, under steady state conditions and when the heat transfer is dependent only on the temperature gradient.
Alternately, it can be thought of as a flux of heat (energy per unit area per unit time) divided by a temperature gradient (temperature difference per unit length)
k=\frac{\Delta Q}{A\times{} \Delta t}\times\frac{x}{\Delta T}
Typical units are SI: W/(m·K) and English units: Btu·ft/(h·ft²·°F). To convert between the two, use the relation 1 Btu·ft/(h·ft²·°F) = 1.730735 W/(m·K). [Perry's Chemical Engineers' Handbook, 7th Edition, Table 1-4]
Examples
In metals, thermal conductivity approximately tracks electrical conductivity according to the Wiedemann-Franz law, as freely moving valence electrons transfer not only electric current but also heat energy. However, the general correlation between electrical and thermal conductance does not hold for other materials, due to the increased importance of phonon carriers for heat in non-metals. As shown in the table below, highly electrically conductive silver is less thermally conductive than diamond, which is an electrical insulator.
Thermal conductivity depends on many properties of a material, notably its structure and temperature. For instance, pure crystalline substances exhibit very different thermal conductivities along different crystal axes, due to differences in phonon coupling along a given crystal axis. Sapphire is a notable example of variable thermal conductivity based on orientation and temperature, for which the CRC Handbook reports a thermal conductivity of 2.6 W/(m·K) perpendicular to the c-axis at 373 K, but 6000 W/(m·K) at 36 degrees from the c-axis and 35 K.
Air and other gases are generally good insulators, in the absence of convection. Therefore, many insulating materials function simply by having a large number of gas-filled pockets which prevent large-scale convection. Examples of these include expanded and extruded polystyrene (popularly referred to as "styrofoam") and silica aerogel. Natural, biological insulators such as fur and feathers achieve similar effects by dramatically inhibiting convection of air or water near an animal's skin.
Thermal conductivity is important in building insulation and related fields. However, materials used in such trades are rarely subjected to chemical purity standards. Several construction materials' k values are listed below. These should be considered approximate due to the uncertainties related to material definitions.
The following table is meant as a small sample of data to illustrate the thermal conductivity of various types of substances. For more complete listings of measured k-values, see the references.
[edit] List of thermal conductivities
Main article: List of thermal conductivities
This is a list of approximate values of thermal conductivity, k, for some common materials. Please consult the list of thermal conductivities for more accurate values, references and detailed information.
Material ↓ Thermal conductivity
W/(m·K) ↓
Cement, Portland [1] 0.29
Concrete, stone [1] 1.7
Air 0.025
Wood 0.04 - 0.4
Alcohols and oils 0.1 - 0.21
Silica Aerogel 0.004-0.03
Soil 1.5
Rubber 0.16
Epoxy (unfilled) 0.19
Hydro-NM-Oxide (Nansulate) 0.018
LPG 0.23 - 0.26
Epoxy (silica-filled) 0.30
Water (liquid) 0.6
Thermal grease 0.7 - 3
Thermal epoxy 1 - 7
Glass 1.1
Ice 2
Sandstone 2.4
Stainless steel[2] 12.11 ~ 45.0
Lead 35.3
Aluminium 237
Gold 318
Copper 401
Silver 429
Diamond 900 - 2320
[edit] Measurement
Main article: Thermal conductivity measurement
Generally speaking, there are a number of possibilities to measure thermal conductivity, each of them suitable for a limited range of materials, depending on the thermal properties and the medium temperature. There can be made a distinction between steady-state and transient techniques.
In general the steady-state techniques perform a measurement when the temperature of the material that is measured does not change with time. This makes the signal analysis straight forward (steady state implies constant signals). The disadvantage generally is that it takes a well-engineered experimental setup. The Divided Bar (various types) is the most common device used for consolidated rock samples.
The transient techniques perform a measurement during the process of heating up. The advantage is that measurements can be made relatively quickly. Transient methods are usually carried out by needle probes (inserted into samples or plunged into the ocean floor).
For good conductors of heat, Searle's bar method can be used.[1] For poor conductors of heat, Lee's disc method can be used.[2] An alternative traditional method using real thermometers is described at [3]. A brief review of new methods measuring thermal conductivity, thermal diffusivity and specific heat within a single measurement is available at [4]. A thermal conductance tester, one of the instruments of gemology, determines if gems are genuine diamonds using diamond's uniquely high thermal conductivity.
[edit] Standard Measurement Techniques
* IEEE Standard 442-1981, "IEEE guide for soil thermal resistivity measurements" see als soil thermal properties [5]
* IEEE Standard 98-2002, "Standard for the Preparation of Test Procedures for the Thermal Evaluation of Solid Electrical Insulating Materials", ISBN 0-7381-3277-2 [6]
* ASTM Standard D5470-06, "Standard Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials" [7]
* ASTM Standard E1225-04, "Standard Test Method for Thermal Conductivity of Solids by Means of the Guarded-Comparative-Longitudinal Heat Flow Technique" [8]
* ASTM Standard D5930-01, "Standard Test Method for Thermal Conductivity of Plastics by Means of a Transient Line-Source Technique" [9]
* ASTM Standard D2717-95, "Standard Test Method for Thermal Conductivity of Liquids" [10]
[edit] Difference between US and European notation
What is called the k-value of construction materials (e.g. window glass) in the US, is called λ-value in Europe.
What is called U-value (= the inverse of R-value) in the US, used to be called k-value in Europe, but is now also called U-value in Europe.
K-value (with capital k) refers in Europe to the total isolation value of a building. K-value is obtained by multiplying the form factor of the building (= the total inward surface of the outward walls of the building divided by the total volume of the building) with the average U-value of the outward walls of the building. K-value is therefore expressed as (m2.m-3).(W.K-1.m-2) = W.K-1.m-3. A house with a volume of 400 m³ and a K-value of 0.45 (the new European norm. It is commonly referred to as K45) will therefore theoretically require 180 W to maintain its interior temperature 1 degree K above exterior temperature. So, to maintain the house at 20°C when it is freezing outside (0°C), 3600 W of continuous heating is required.
[edit] Related terms
The reciprocal of thermal conductivity is thermal resistivity, measured in kelvin-metres per watt (K·m·W−1).
When dealing with a known amount of material, its thermal conductance and the reciprocal property, thermal resistance, can be described. Unfortunately there are differing definitions for these terms.
[edit] Thermal Conductance
For general scientific use, thermal conductance is the quantity of heat that passes in unit time through a plate of particular area and thickness when its opposite faces differ in temperature by one degree. For a plate of thermal conductivity k, area A and thickness L this is kA/L, measured in W·K−1 (equivalent to: W/°C). Thermal conductivity and conductance are analogous to electrical conductivity (A·m−1·V−1) and electrical conductance (A·V−1).
There is also a measure known as heat transfer coefficient: the quantity of heat that passes in unit time through unit area of a plate of particular thickness when its opposite faces differ in temperature by one degree. The reciprocal is thermal insulance. In summary:
* thermal conductance = kA/L, measured in W·K−1
o thermal resistance = L/kA, measured in K·W−1 (equivalent to: °C/W)
* heat transfer coefficient = k/L, measured in W·K−1·m−2
o thermal insulance = L/k, measured in K·m²·W−1.
The heat transfer coefficient is also known as thermal admittance
[edit] Thermal Resistance
When thermal resistances occur in series, they are additive. So when heat flows through two components each with a resistance of 1 °C/W, the total resistance is 2 °C/W.
A common engineering design problem involves the selection of an appropriate sized heat sink for a given heat source. Working in units of thermal resistance greatly simplifies the design calculation. The following formula can be used to estimate the performance:
R_{hs} = \frac {\Delta T}{P_{th}} - R_s
where:
* Rhs is the maximum thermal resistance of the heat sink to ambient, in °C/W
* ΔT is the temperature difference (temperature drop), in °C
* Pth is the thermal power (heat flow), in Watts
* Rs is the thermal resistance of the heat source, in °C/W
For example, if a component produces 100 W of heat, and has a thermal resistance of 0.5 °C/W, what is the maximum thermal resistance of the heat sink? Suppose the maximum temperature is 125 °C, and the ambient temperature is 25 °C; then the ΔT is 100 °C. The heat sink's thermal resistance to ambient must then be 0.5 °C/W or less.
[edit] Alternate definition (buildings)
When dealing with buildings, thermal resistance or R-value means what is described above as thermal insulance, and thermal conductance means the reciprocal. For materials in series, these thermal resistances (unlike conductances) can simply be added to give a thermal resistance for the whole.
A third term, thermal transmittance, incorporates the thermal conductance of a structure along with heat transfer due to convection and radiation. It is measured in the same units as thermal conductance and is sometimes known as the composite thermal conductance. The term U-value is another synonym.
In summary, for a plate of thermal conductivity k (the k value [3]), area A and thickness L:
* thermal conductance = k/L, measured in W·K−1·m−2;
* thermal resistance (R value) = L/k, measured in K·m²·W−1;
* thermal transmittance (U value) = 1/(Σ(L/k)) + convection + radiation, measured in W·K−1·m−2.
[edit] Textile industry
In textiles, a tog value may be quoted as a measure of thermal resistance in place of a measure in SI units.
[edit] Origins
The thermal conductivity of a system is determined by how atoms comprising the system interact. There are no simple, correct expressions for thermal conductivity. There are two different approaches for calculating the thermal conductivity of a system.
The first approach employs the Green-Kubo relations. Although this employs analytic expressions which in principle can be solved, in order to calculate the thermal conductivity of a dense fluid or solid using this relation requires the use of molecular dynamics computer simulation.
The second approach is based upon the relaxation time approach. Due to the anharmonicity within the crystal potential, the phonons in the system are known to scatter. There are three main mechanisms for scattering:
* Boundary scattering, a phonon hitting the boundary of a system;
* Mass defect scattering, a phonon hitting an impurity within the system and scattering;
* Phonon-phonon scattering, a phonon breaking into two lower energy phonons or a phonon colliding with another phonon and merging into one higher energy phonon.
Further information can be found in the publication "The Physics of Phonons" by G P Srivastava.
[edit] See also
* Heat conduction
* Heat transfer
* Heat transfer mechanisms
* Insulated pipes
* R-value
* Specific Heat
* Thermal bridge
* Thermal contact conductance
* Thermal diffusivity
* Thermal resistance in electronics
* Thermistor
* Thermocouple
* Electrical conductivity
[edit] External links
* Table with the Thermal Conductivity of the Elements
* http://physics.nist.gov/Pubs/SP811/appenB9.html
* http://www.npl.co.uk/thermal/faq_index.html#heat%20transfer%20property thermophysics FAQ5
* http://www.ornl.gov/roofs+walls/research/detailed_papers/rastra/dynamic.htm
* http://www.tak2000.com/data2.htm
* http://thermophys.savba.sk
* Calculation of the Thermal Conductivity of Glass Calculation of the Thermal Conductivity of Glass at Room Temperature from the Chemical Composition
* http://www.mathisinstruments.com/index.asp?pathinfo=/html/content/technology/tech_glossary.asp&dbbypass=
* Viscosity and Thermal Conductivity Equations for Nitrogen, Oxygen, Argon, and Air
[edit] References
1. ^ a b Thermal Conductivity of some common Materials
2. ^ Thermal Conductivity of Metals
3. ^ Definition of k value from Plastics New Zealand
* Callister, William (2003). "Appendix B", Materials Science and Engineering - An Introduction. John Wiley & Sons, INC, 757. ISBN 0-471-22471-5.
* Halliday, David; Resnick, Robert; & Walker, Jearl(1997). Fundamentals of Physics (5th ed.). John Wiley and Sons, INC., NY ISBN 0-471-10558-9.
* TM 5-852-6 AFR 88-19, Volume 6 (Army Corp of Engineers publication)
* Srivastava G. P (1990), "The Physics of Phonons." Adam Hilger, IOP Publishing Ltd, Bristol.
LEARN DESK
Thermal Conductivity - http://en.wikipedia.org/wiki/Thermal_conductivity
Heat Conductivity - http://en.wikipedia.org/wiki/Heat_conduction
First, we define heat conduction by the formula:
H=\frac{\Delta Q}{\Delta t}=k\times A\times\frac{\Delta T}{x}
where \frac{\Delta Q}{\Delta t} is the rate of heat flow, k is the thermal conductivity, A is the total surface area of conducting surface, ΔT is temperature difference and x is the thickness of conducting surface separating the 2 temperatures.
Thus, rearranging the equation gives thermal conductivity,
k=\frac{\Delta Q}{\Delta t}\times\frac{1}{A}\times\frac{x}{\Delta T}
(Note: \frac{\Delta T}{x} is the temperature gradient)
In other words, it is defined as the quantity of heat, ΔQ, transmitted during time Δt through a thickness x, in a direction normal to a surface of area A, due to a temperature difference ΔT, under steady state conditions and when the heat transfer is dependent only on the temperature gradient.
Alternately, it can be thought of as a flux of heat (energy per unit area per unit time) divided by a temperature gradient (temperature difference per unit length)
k=\frac{\Delta Q}{A\times{} \Delta t}\times\frac{x}{\Delta T}
Typical units are SI: W/(m·K) and English units: Btu·ft/(h·ft²·°F). To convert between the two, use the relation 1 Btu·ft/(h·ft²·°F) = 1.730735 W/(m·K). [Perry's Chemical Engineers' Handbook, 7th Edition, Table 1-4]
Examples
In metals, thermal conductivity approximately tracks electrical conductivity according to the Wiedemann-Franz law, as freely moving valence electrons transfer not only electric current but also heat energy. However, the general correlation between electrical and thermal conductance does not hold for other materials, due to the increased importance of phonon carriers for heat in non-metals. As shown in the table below, highly electrically conductive silver is less thermally conductive than diamond, which is an electrical insulator.
Thermal conductivity depends on many properties of a material, notably its structure and temperature. For instance, pure crystalline substances exhibit very different thermal conductivities along different crystal axes, due to differences in phonon coupling along a given crystal axis. Sapphire is a notable example of variable thermal conductivity based on orientation and temperature, for which the CRC Handbook reports a thermal conductivity of 2.6 W/(m·K) perpendicular to the c-axis at 373 K, but 6000 W/(m·K) at 36 degrees from the c-axis and 35 K.
Air and other gases are generally good insulators, in the absence of convection. Therefore, many insulating materials function simply by having a large number of gas-filled pockets which prevent large-scale convection. Examples of these include expanded and extruded polystyrene (popularly referred to as "styrofoam") and silica aerogel. Natural, biological insulators such as fur and feathers achieve similar effects by dramatically inhibiting convection of air or water near an animal's skin.
Thermal conductivity is important in building insulation and related fields. However, materials used in such trades are rarely subjected to chemical purity standards. Several construction materials' k values are listed below. These should be considered approximate due to the uncertainties related to material definitions.
The following table is meant as a small sample of data to illustrate the thermal conductivity of various types of substances. For more complete listings of measured k-values, see the references.
[edit] List of thermal conductivities
Main article: List of thermal conductivities
This is a list of approximate values of thermal conductivity, k, for some common materials. Please consult the list of thermal conductivities for more accurate values, references and detailed information.
Material ↓ Thermal conductivity
W/(m·K) ↓
Cement, Portland [1] 0.29
Concrete, stone [1] 1.7
Air 0.025
Wood 0.04 - 0.4
Alcohols and oils 0.1 - 0.21
Silica Aerogel 0.004-0.03
Soil 1.5
Rubber 0.16
Epoxy (unfilled) 0.19
Hydro-NM-Oxide (Nansulate) 0.018
LPG 0.23 - 0.26
Epoxy (silica-filled) 0.30
Water (liquid) 0.6
Thermal grease 0.7 - 3
Thermal epoxy 1 - 7
Glass 1.1
Ice 2
Sandstone 2.4
Stainless steel[2] 12.11 ~ 45.0
Lead 35.3
Aluminium 237
Gold 318
Copper 401
Silver 429
Diamond 900 - 2320
[edit] Measurement
Main article: Thermal conductivity measurement
Generally speaking, there are a number of possibilities to measure thermal conductivity, each of them suitable for a limited range of materials, depending on the thermal properties and the medium temperature. There can be made a distinction between steady-state and transient techniques.
In general the steady-state techniques perform a measurement when the temperature of the material that is measured does not change with time. This makes the signal analysis straight forward (steady state implies constant signals). The disadvantage generally is that it takes a well-engineered experimental setup. The Divided Bar (various types) is the most common device used for consolidated rock samples.
The transient techniques perform a measurement during the process of heating up. The advantage is that measurements can be made relatively quickly. Transient methods are usually carried out by needle probes (inserted into samples or plunged into the ocean floor).
For good conductors of heat, Searle's bar method can be used.[1] For poor conductors of heat, Lee's disc method can be used.[2] An alternative traditional method using real thermometers is described at [3]. A brief review of new methods measuring thermal conductivity, thermal diffusivity and specific heat within a single measurement is available at [4]. A thermal conductance tester, one of the instruments of gemology, determines if gems are genuine diamonds using diamond's uniquely high thermal conductivity.
[edit] Standard Measurement Techniques
* IEEE Standard 442-1981, "IEEE guide for soil thermal resistivity measurements" see als soil thermal properties [5]
* IEEE Standard 98-2002, "Standard for the Preparation of Test Procedures for the Thermal Evaluation of Solid Electrical Insulating Materials", ISBN 0-7381-3277-2 [6]
* ASTM Standard D5470-06, "Standard Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials" [7]
* ASTM Standard E1225-04, "Standard Test Method for Thermal Conductivity of Solids by Means of the Guarded-Comparative-Longitudinal Heat Flow Technique" [8]
* ASTM Standard D5930-01, "Standard Test Method for Thermal Conductivity of Plastics by Means of a Transient Line-Source Technique" [9]
* ASTM Standard D2717-95, "Standard Test Method for Thermal Conductivity of Liquids" [10]
[edit] Difference between US and European notation
What is called the k-value of construction materials (e.g. window glass) in the US, is called λ-value in Europe.
What is called U-value (= the inverse of R-value) in the US, used to be called k-value in Europe, but is now also called U-value in Europe.
K-value (with capital k) refers in Europe to the total isolation value of a building. K-value is obtained by multiplying the form factor of the building (= the total inward surface of the outward walls of the building divided by the total volume of the building) with the average U-value of the outward walls of the building. K-value is therefore expressed as (m2.m-3).(W.K-1.m-2) = W.K-1.m-3. A house with a volume of 400 m³ and a K-value of 0.45 (the new European norm. It is commonly referred to as K45) will therefore theoretically require 180 W to maintain its interior temperature 1 degree K above exterior temperature. So, to maintain the house at 20°C when it is freezing outside (0°C), 3600 W of continuous heating is required.
[edit] Related terms
The reciprocal of thermal conductivity is thermal resistivity, measured in kelvin-metres per watt (K·m·W−1).
When dealing with a known amount of material, its thermal conductance and the reciprocal property, thermal resistance, can be described. Unfortunately there are differing definitions for these terms.
[edit] Thermal Conductance
For general scientific use, thermal conductance is the quantity of heat that passes in unit time through a plate of particular area and thickness when its opposite faces differ in temperature by one degree. For a plate of thermal conductivity k, area A and thickness L this is kA/L, measured in W·K−1 (equivalent to: W/°C). Thermal conductivity and conductance are analogous to electrical conductivity (A·m−1·V−1) and electrical conductance (A·V−1).
There is also a measure known as heat transfer coefficient: the quantity of heat that passes in unit time through unit area of a plate of particular thickness when its opposite faces differ in temperature by one degree. The reciprocal is thermal insulance. In summary:
* thermal conductance = kA/L, measured in W·K−1
o thermal resistance = L/kA, measured in K·W−1 (equivalent to: °C/W)
* heat transfer coefficient = k/L, measured in W·K−1·m−2
o thermal insulance = L/k, measured in K·m²·W−1.
The heat transfer coefficient is also known as thermal admittance
[edit] Thermal Resistance
When thermal resistances occur in series, they are additive. So when heat flows through two components each with a resistance of 1 °C/W, the total resistance is 2 °C/W.
A common engineering design problem involves the selection of an appropriate sized heat sink for a given heat source. Working in units of thermal resistance greatly simplifies the design calculation. The following formula can be used to estimate the performance:
R_{hs} = \frac {\Delta T}{P_{th}} - R_s
where:
* Rhs is the maximum thermal resistance of the heat sink to ambient, in °C/W
* ΔT is the temperature difference (temperature drop), in °C
* Pth is the thermal power (heat flow), in Watts
* Rs is the thermal resistance of the heat source, in °C/W
For example, if a component produces 100 W of heat, and has a thermal resistance of 0.5 °C/W, what is the maximum thermal resistance of the heat sink? Suppose the maximum temperature is 125 °C, and the ambient temperature is 25 °C; then the ΔT is 100 °C. The heat sink's thermal resistance to ambient must then be 0.5 °C/W or less.
[edit] Alternate definition (buildings)
When dealing with buildings, thermal resistance or R-value means what is described above as thermal insulance, and thermal conductance means the reciprocal. For materials in series, these thermal resistances (unlike conductances) can simply be added to give a thermal resistance for the whole.
A third term, thermal transmittance, incorporates the thermal conductance of a structure along with heat transfer due to convection and radiation. It is measured in the same units as thermal conductance and is sometimes known as the composite thermal conductance. The term U-value is another synonym.
In summary, for a plate of thermal conductivity k (the k value [3]), area A and thickness L:
* thermal conductance = k/L, measured in W·K−1·m−2;
* thermal resistance (R value) = L/k, measured in K·m²·W−1;
* thermal transmittance (U value) = 1/(Σ(L/k)) + convection + radiation, measured in W·K−1·m−2.
[edit] Textile industry
In textiles, a tog value may be quoted as a measure of thermal resistance in place of a measure in SI units.
[edit] Origins
The thermal conductivity of a system is determined by how atoms comprising the system interact. There are no simple, correct expressions for thermal conductivity. There are two different approaches for calculating the thermal conductivity of a system.
The first approach employs the Green-Kubo relations. Although this employs analytic expressions which in principle can be solved, in order to calculate the thermal conductivity of a dense fluid or solid using this relation requires the use of molecular dynamics computer simulation.
The second approach is based upon the relaxation time approach. Due to the anharmonicity within the crystal potential, the phonons in the system are known to scatter. There are three main mechanisms for scattering:
* Boundary scattering, a phonon hitting the boundary of a system;
* Mass defect scattering, a phonon hitting an impurity within the system and scattering;
* Phonon-phonon scattering, a phonon breaking into two lower energy phonons or a phonon colliding with another phonon and merging into one higher energy phonon.
Further information can be found in the publication "The Physics of Phonons" by G P Srivastava.
[edit] See also
* Heat conduction
* Heat transfer
* Heat transfer mechanisms
* Insulated pipes
* R-value
* Specific Heat
* Thermal bridge
* Thermal contact conductance
* Thermal diffusivity
* Thermal resistance in electronics
* Thermistor
* Thermocouple
* Electrical conductivity
[edit] External links
* Table with the Thermal Conductivity of the Elements
* http://physics.nist.gov/Pubs/SP811/appenB9.html
* http://www.npl.co.uk/thermal/faq_index.html#heat%20transfer%20property thermophysics FAQ5
* http://www.ornl.gov/roofs+walls/research/detailed_papers/rastra/dynamic.htm
* http://www.tak2000.com/data2.htm
* http://thermophys.savba.sk
* Calculation of the Thermal Conductivity of Glass Calculation of the Thermal Conductivity of Glass at Room Temperature from the Chemical Composition
* http://www.mathisinstruments.com/index.asp?pathinfo=/html/content/technology/tech_glossary.asp&dbbypass=
* Viscosity and Thermal Conductivity Equations for Nitrogen, Oxygen, Argon, and Air
[edit] References
1. ^ a b Thermal Conductivity of some common Materials
2. ^ Thermal Conductivity of Metals
3. ^ Definition of k value from Plastics New Zealand
* Callister, William (2003). "Appendix B", Materials Science and Engineering - An Introduction. John Wiley & Sons, INC, 757. ISBN 0-471-22471-5.
* Halliday, David; Resnick, Robert; & Walker, Jearl(1997). Fundamentals of Physics (5th ed.). John Wiley and Sons, INC., NY ISBN 0-471-10558-9.
* TM 5-852-6 AFR 88-19, Volume 6 (Army Corp of Engineers publication)
* Srivastava G. P (1990), "The Physics of Phonons." Adam Hilger, IOP Publishing Ltd, Bristol.
LEARN DESK
Thermal Conductivity - http://en.wikipedia.org/wiki/Thermal_conductivity
Heat Conductivity - http://en.wikipedia.org/wiki/Heat_conduction
Wednesday, August 27, 2008
Arctic Sea Ice Nears Record Low
By AP/DAN JOLING
Wednesday, Aug. 27, 2008
Time.com
[photo caption] A chunk of ice drifts after it separated from the Ward Hunt Ice Shelf off the north coast of Ellesmere Island in Canada.
Arctic Ocean sea ice has melted to the second lowest minimum since satellite observations began, according to scientists at the National Snow and Ice Data Center.
Sea ice melt recorded on Monday exceeded the low recorded in 2005, which had held second place.
With several weeks left in the melt season, ice in summer 2008 has a chance to diminish below the record low set last year, according to scientists at the National Snow and Ice Data Center.
Environmental groups said the ice melt was another alarm bell warning of global warming.
"It's an unfortunate sign that climate change is coming rapidly to the Arctic and that we really need to address the issue of global warming on a national level," said Christopher Krenz, Arctic project manager for Oceana.
"This is not surprising but it is alarming," said Deborah Williams, a former Interior Department special assistant for Alaska. "This was a relatively cool summer, and to have ice decrease to the second lowest minimum on record demonstrates that global warming's ongoing impact is profound."
The National Snow and Ice Data Center, based at the University of Colorado, reported the ice Monday melted below the 2005 minimum of 2.05 million square miles set on Sept. 21 that year. Exact figures will be released Wednesday.
Through the beginning of the melt season in May until early August, daily ice extent for 2008 closely tracked the values for 2005, the center said.
In early August 2005, the decline began to slow. In August 2008, however, the decline has remained steadily downward at a brisk pace.
The most recent ice retreat primarily reflects melt in the Chukchi Sea off Alaska's northwest coast and the East Siberian Seas off the coast of eastern Russia, according to the center.
The Chukchi Sea is home to one of two populations of Alaska polar bears.
Federal observers flying for a whale survey on Aug. 16 spotted nine polar bears swimming in open ocean in the Chukchi Sea. The bears were 15 to 65 miles off the Alaska shore. Some were swimming north, apparently trying to reach the polar ice edge, which on that day was 400 miles away.
Polar bears are powerful swimmers and have been recorded on swims of 100 miles but the ordeal can leave them exhausted and susceptible to drowning in high seas.
Sea ice is the primary habitat of polar bears. They depend on it to hunt their primary prey, ringed seals, which create lairs on ice for breeding maintain breathing holes with powerful claws.
Summer sea ice last year shrunk to about 1.65 million square miles, nearly 40 percent less than the long-term average between 1979 and 2000. Most climate modelers predict a continued downward spiral, possibly with an Arctic Ocean that's ice free during summer months by 2030 or sooner.
Krenz said the announcement Tuesday showed that last year's record low sea ice was not an anomaly. As ice covers fewer square miles of ocean, he said, warming will accelerate.
"It's going to accelerate climate change through changes in the reflectance of the Arctic," he said. "It's going from bright ice to a much darker ocean."
More square miles of dark ocean will absorb more heat. More warmth will accelerate melting of Arctic permafrost, allowing organic matter now frozen to melt and add to the greenhouse gas problem, he said.
"That allows for the breakdown of that by bacteria and other organisms that release CO2 or methane, depending on how the breakdown occurs," he said.
The effects faced by people in the Arctic eventually will reach the rest of the nation and the world, he warned.
Wednesday, Aug. 27, 2008
Time.com
[photo caption] A chunk of ice drifts after it separated from the Ward Hunt Ice Shelf off the north coast of Ellesmere Island in Canada.
Arctic Ocean sea ice has melted to the second lowest minimum since satellite observations began, according to scientists at the National Snow and Ice Data Center.
Sea ice melt recorded on Monday exceeded the low recorded in 2005, which had held second place.
With several weeks left in the melt season, ice in summer 2008 has a chance to diminish below the record low set last year, according to scientists at the National Snow and Ice Data Center.
Environmental groups said the ice melt was another alarm bell warning of global warming.
"It's an unfortunate sign that climate change is coming rapidly to the Arctic and that we really need to address the issue of global warming on a national level," said Christopher Krenz, Arctic project manager for Oceana.
"This is not surprising but it is alarming," said Deborah Williams, a former Interior Department special assistant for Alaska. "This was a relatively cool summer, and to have ice decrease to the second lowest minimum on record demonstrates that global warming's ongoing impact is profound."
The National Snow and Ice Data Center, based at the University of Colorado, reported the ice Monday melted below the 2005 minimum of 2.05 million square miles set on Sept. 21 that year. Exact figures will be released Wednesday.
Through the beginning of the melt season in May until early August, daily ice extent for 2008 closely tracked the values for 2005, the center said.
In early August 2005, the decline began to slow. In August 2008, however, the decline has remained steadily downward at a brisk pace.
The most recent ice retreat primarily reflects melt in the Chukchi Sea off Alaska's northwest coast and the East Siberian Seas off the coast of eastern Russia, according to the center.
The Chukchi Sea is home to one of two populations of Alaska polar bears.
Federal observers flying for a whale survey on Aug. 16 spotted nine polar bears swimming in open ocean in the Chukchi Sea. The bears were 15 to 65 miles off the Alaska shore. Some were swimming north, apparently trying to reach the polar ice edge, which on that day was 400 miles away.
Polar bears are powerful swimmers and have been recorded on swims of 100 miles but the ordeal can leave them exhausted and susceptible to drowning in high seas.
Sea ice is the primary habitat of polar bears. They depend on it to hunt their primary prey, ringed seals, which create lairs on ice for breeding maintain breathing holes with powerful claws.
Summer sea ice last year shrunk to about 1.65 million square miles, nearly 40 percent less than the long-term average between 1979 and 2000. Most climate modelers predict a continued downward spiral, possibly with an Arctic Ocean that's ice free during summer months by 2030 or sooner.
Krenz said the announcement Tuesday showed that last year's record low sea ice was not an anomaly. As ice covers fewer square miles of ocean, he said, warming will accelerate.
"It's going to accelerate climate change through changes in the reflectance of the Arctic," he said. "It's going from bright ice to a much darker ocean."
More square miles of dark ocean will absorb more heat. More warmth will accelerate melting of Arctic permafrost, allowing organic matter now frozen to melt and add to the greenhouse gas problem, he said.
"That allows for the breakdown of that by bacteria and other organisms that release CO2 or methane, depending on how the breakdown occurs," he said.
The effects faced by people in the Arctic eventually will reach the rest of the nation and the world, he warned.
Monday, July 7, 2008
Argentine glacier Perito Moreno about to break
Posted : Mon, 07 Jul 2008 16:34:01 GMT
Author : DPA
The Earth Times
Buenos Aires - The southern Argentine glacier Perito Moreno was set to fracture Monday, in a rare collapse during the winter in the southern hemisphere. Give the unusual timing for this spectacular natural phenomenon, foreign tourists did not gather by the thousand in the area, as has happened on other years.
It was mostly a local crowd who waited to see how the glacier - a natural dike into the lake Lago Argentino, made of millions of tonnes of ice - breaks in a deafening crash.
Despite the snow, the rain and very low temperatures, some 1,500 people travelled 80 kilometres on dirt roads from the town of El Calafate to the glacier, inside the Glaciers National Park.
The glacier started to let water in on Friday, and a tunnel was created through the ice whose roof was expected to collapse Monday.
The Perito Moreno, in the Argentine Patagonian province of Santa Cruz, is one of the few still-growing glaciers in the world. In the process, it dams up large masses of water. There is a difference of up to 30 metres in altitude between water on the two sides of the ice barrier, which can be up to 60 metres high itself.
Large blocks of ice have already collapsed in recent days, and the definitive crash appeared imminent Monday, Argentine media reported.
Recent episodes of the phenomenon were to be seen in 2004 and 2006, when the ice barrier collapsed causing a huge avalanche of water. The region, some 2,500 kilometres south-west of Buenos Aires, is very thinly populated, and the phenomenon does not entail risks for people or property.
The Perito Moreno last collapsed in winter in 1951.
Author : DPA
The Earth Times
Buenos Aires - The southern Argentine glacier Perito Moreno was set to fracture Monday, in a rare collapse during the winter in the southern hemisphere. Give the unusual timing for this spectacular natural phenomenon, foreign tourists did not gather by the thousand in the area, as has happened on other years.
It was mostly a local crowd who waited to see how the glacier - a natural dike into the lake Lago Argentino, made of millions of tonnes of ice - breaks in a deafening crash.
Despite the snow, the rain and very low temperatures, some 1,500 people travelled 80 kilometres on dirt roads from the town of El Calafate to the glacier, inside the Glaciers National Park.
The glacier started to let water in on Friday, and a tunnel was created through the ice whose roof was expected to collapse Monday.
The Perito Moreno, in the Argentine Patagonian province of Santa Cruz, is one of the few still-growing glaciers in the world. In the process, it dams up large masses of water. There is a difference of up to 30 metres in altitude between water on the two sides of the ice barrier, which can be up to 60 metres high itself.
Large blocks of ice have already collapsed in recent days, and the definitive crash appeared imminent Monday, Argentine media reported.
Recent episodes of the phenomenon were to be seen in 2004 and 2006, when the ice barrier collapsed causing a huge avalanche of water. The region, some 2,500 kilometres south-west of Buenos Aires, is very thinly populated, and the phenomenon does not entail risks for people or property.
The Perito Moreno last collapsed in winter in 1951.
Ice dam to break prematurely on Argentine glacier
07 July 2008
BUENOS AIRES (AFP) — A huge ice dam on Argentina's Perito Moreno glacier will break apart for the first time in the southern hemisphere winter, likely as a result of global warming, scientists and environmentalists said Monday.
The 60-meter (yard) high wall of ice holding back a portion of Lake Argentina breaks apart spectacularly in cycles of one year to several years, but always in summer, and is one of Patagonia's top tourist attractions.
"This is the first time the glacier breaks up in winter. It could be related to global warming as rising temperatures affects ice friction," said Los Glaciares National Park director Carlos Corvalan.
The Perito Moreno glacier, one of the world's largest, measuring 275 square kilometers (106 square miles) and five kilometers (three miles) wide at its mouth, is located 2,800 kilometers (1,740 miles) southeast of Buenos Aires.
BUENOS AIRES (AFP) — A huge ice dam on Argentina's Perito Moreno glacier will break apart for the first time in the southern hemisphere winter, likely as a result of global warming, scientists and environmentalists said Monday.
The 60-meter (yard) high wall of ice holding back a portion of Lake Argentina breaks apart spectacularly in cycles of one year to several years, but always in summer, and is one of Patagonia's top tourist attractions.
"This is the first time the glacier breaks up in winter. It could be related to global warming as rising temperatures affects ice friction," said Los Glaciares National Park director Carlos Corvalan.
The Perito Moreno glacier, one of the world's largest, measuring 275 square kilometers (106 square miles) and five kilometers (three miles) wide at its mouth, is located 2,800 kilometers (1,740 miles) southeast of Buenos Aires.
Monday, June 23, 2008
66 Ways To Save Money on Gasoline
by Mark Ontkush, Boston, Massachusetts, USA on 06.23.08
Cars & Transportation (cars)
While the rising cost of oil has the price of gasoline skyrocketing faster than global warming is melting glaciers, people everywhere are preparing for cross-country road trips to Grand Canyon National Park and summer camps in Maine. We can't really argue with that innate desire to get closer to nature and out on the open road, and whether you're a die-hard cyclist or a still driving an SUV, chances are you plan to get in a car to go somewhere this summer. So whether you're packing up the Prius for some close-to-home camping, towing the boat to far-away shores, or merely fighting the crosstown traffic, these money- and gas-saving tips are designed to help you squeeze every last bit of power out of that precious petrol--and cause fewer CO2 emissions, too. It's a comprehensive list--several tasks should be done before even starting your car; others require minor adjustments to your driving style. All of them aim to help you drive a little greener.
Gas-Saving Tips: Questions to Ask Before You Turn on the Engine
1. Is your engine tuned up? Fixing a car that is out of tune (or has failed an emissions test) will boost gas mileage, so be sure to give your car regular tune-ups. You'll also want to watch out for worn spark plugs. A misfiring spark plug can dramatically reduce a car's fuel efficiency.
2. Is your body in good shape?
Inspect suspension and chassis parts for occasional misalignment. Bent wheels, axles, bad shocks, broken springs, et cetera create engine drag and are unsafe at high traveling speeds.
3. Is your air filter clean?
When the engine air filter clogs with dirt, dust and bugs, it causes your engine to work harder and your car becomes less fuel-efficient. Replacing a clogged air filter could improve your gas mileage by as much as 10 percent. It's a good idea to have your engine air filter checked at each oil change.
4. What grade is your oil?
You can improve your car's gas mileage by using the manufacturer's recommended grade of motor oil. Opt for motor oil with the words "energy conserving" on the API performance label; this oil contains friction-reducing additives.
5. Got shade?
Buy a good windshield shade. A windshield shade blocks sunlight and helps to keep heat out of the inside of your car. This will help reduce air conditioning use in the summer.
Ways to Save Money on Gas at the Pump
6. Don't overfill 'er up. Avoid filling your gas tank to the top. Overfilling results in sloshing over and out of tank. Never fill gas tank past the first "click" of fuel nozzle if the nozzle is automatic.
7. Use the lowest octane you can.
Buy the lowest grade or octane of gasoline that is appropriate for your car; pricey premium fuel won't boost your car's fuel economy.
8. Tighten that cap.
Gas will evaporate from your car's gas tank if it has an escape. Loose, missing, or damaged gas caps cause millions of gallons of gas to evaporate each year.
9. Wait until you're near empty.
Don't fill up until your tank is near empty; this will extend your gas because you are hauling a lighter load as the tank nears empty.
10. Find credit card discounts.
Some credit cards offer gas savings when you use the card for purchases. This works in much the same way that some credit card companies give you frequent-flier miles when you use their card for purchases.
11. Membership has its privileges.
Some gas stations offer membership benefits. There are also department and grocery stores that give discounts at the fuel pump when you use their store membership cards.
12. Screw the brand names.
Brand means nothing in the gas world; they are all using the same refineries, trucks, and pipelines to transport the fuel. Go for cost savings when it comes to the price of gas.
13. Keep your eyes on the prize.
Scope out gas prices while you're driving (but keep your eyes on the road, Smokey.) Some gas stations offer free coffee with fill up as well. And if it's not shade-grown and organic? Meh...live a little.
14. Don't get desperate.
The first gas station you encounter after a long thirsty stretch will never be the cheapest - drive a little further to find a cheaper station.
15. In the city, don't shop around.
Don't price shop for gas locally by driving around, the miles you drive will almost certainly eliminate the savings, and stop-and-go city traffic does a number on your average efficiency, not to mention your greenhouse gas emissions.
16. Exit, stage left. On the highway, that is.
On the highway, take an exit at a moderately sized city and head for the city center. There will likely be several stations near the ramp with cheaper gas.
record_gas_prices.jpg
More Ways to Save Gas: Things to Check Before You Get on the Road
17. Are they open? Is the place you are going to open for business? Shops often have irregular hours, especially at nights and on the weekends. Always, always, always call or go online first!
18. Do you know where you are going?
Have you confirmed that the address you are given actually exists and is accurate? IF not, you could be wasting fuel and time on miles being lost.
19. Did you do your due diligence?
Use the Interwebz, newspapers, or phone book to comparison shop before you drive around to several stores.
20. Do they have what you want?
Restaurants often have long waits, products can be out of stock, and so on. Confirm that the place you're headed can deliver the goods before you get there.
21. Can it be delivered?
Find companies willing to delivery what you need to your home. Amazon, dry cleaning delivery services, food, and anything else that will bring what you need without burning up your gas may save some loot and the planet some warming.
22. Do you have to go right now?
Traveling in off-peak times will reduce your time spent in traffic, waiting for lights, etc.
23. Can you combine trips?
Combine errands into one trip and plan your stops for the most efficient route. You'll save yourself time and money.
Ways to Save Gas and Money: Are You Using Your Vehicle Wisely?
24. Could you walk or bike? Just burn calories, man. Pay attention to why, where, and when you drive.
25. Is there a public transportation option available?
Look into public transportation; after you figure in driving around for parking and such, it may actually be faster.
26. Should you get a rental car?
A small car almost always has a better fuel economy due to its smaller mass; in certain situations you may want to rent a smaller vehicle for the trip instead of using your own. (Conversely, you can also choose to buy a smaller car from the get-go, and rent a larger one only when necessary.)
27. Did you maximize the square footage of your vehicle?
For human cargo, carpools reduce travel monotony and gas expense--all riders chip in to help you buy. Carpooling also reduces traffic congestion, gives the driver easier maneuverability and greater "steady speed" economy. If you're hauling materials such as wood, fill the whole vehicle on each trip.
How to Save Gas by Planning Your Route
28. No rough stuff. Riding on dirt or gravel will rob you of up to 30% of your gas mileage.
29. Use alternate roads when safer, shorter, and straighter.
Compare traveling distance differences--remember that corners, curves and lane jumping requires extra gas. The shortest distance between two points is always straight as the crow flies.
30. Avoid heavy traffic and lots of traffic lights.
The shortest route is not always the most fuel efficient if you have to stop a lot.
Getting Ready for Takeoff
31. Are your tires fat or flat? Proper tire pressure will give you better gas mileage. Inflate all tires to maximum limit; each tire should also be periodically spun, balanced and checked for out-of-roundness.
32. Lose the top.
Remove vinyl tops, they cause air drag.
33. Lose the racks.
Remove ski, bicycle, or luggage racks from your roof if you don't need it. They also cause air drag.
34. Drop the rest of the dead weight.
Get rid of all extra tires, back seats, unnecessary heavy parts. Extra weight reduces mileage, especially when driving up inclines.
35. Trucks, drop the tailgate.
You will get more mileage if you put down the tailgate due to less wind resistance.
36. Use your GPS.
A GPS unit will pay for itself in wasted time and gas very quickly.
How To Save Gas During Engine Startup
37. Turn off electronics. Starting your car with electronic devices, like the radio, air conditioning, and 12-volt refrigerator turned off will put less strain on your engine which translates to better gas mileages.
38. Close the sun or moon roof.
Having these open will increase drag.
39. Turn the key and get moving.
Modern vehicles do not need to be warmed up, even on cold mornings - 30 seconds is plenty of time.
40. Turn off the choke.
If the car is revving, check that the automatic choke is disengaged after engine warm up.
41. Check for leaks.
Before you take your car out, check the driveway for gas tank leaks. Even little ones can waste plenty of fuel over time.
Ways to Save Gas While On The Road
42. Drive steadily.Slowing down or speeding up wastes fuel. Maintain a steady pace--the ideal trip is one where you never stop except for signs and lights.
43. Don't exceed the legal speed limit.
However tough it may be to comprehend, the primarily goal of a speed limit for your traveling safety. However, it is also a good estimate of the most efficient speed for the road as well.
44. Careful with those brakes.
A car consumes the most gas as it accelerates, while a moving car doesn't require much gasoline to keep moving. Ideally, the brake should be used sparingly--expert hypermilers roll to a dead stop at every red light and stop sign.
45. Shift up early and down late.
If you have a manual transmission and want to save some gas, here's a hot tip: You need to shift up as soon as you can and shift down as the last possible moment.
46. Avoid hard stops.
Panic or hard stops will also cost you; anticipate stop signs, pedestrian walkways, and traffic lights.
47. Get on the good foot: Use your right one only.
To avoid riding the brake and wasting gas, use your right foot to control both pedals.
48. Don't weave.
The more you weave the more gas you burn. Keep your wheel still and steady as she goes.
49. Don't accelerate up hill.
Don’t accelerate up a hill. When approaching it, build up speed before the incline, maintain on the way up, then coast down.
50. Follow traffic reports.
The radio is the road's information superhighway, and traffic reports are there for a reason. Use them to avoid jams and other delays, which can help keep your momentum steady.
How To Save Gas During City Driving
51. Eliminate jack-rabbit starts. Always accelerate slowly when starting from a dead stop. A good rule of thumb is to not push the pedal down more than 1/4 of the total foot travel.
52. Beat the Wind.
Exceeding 40 mph forces your auto to overcome tremendous wind resistance, which will dramatically decrease your mileage. Try and keep it under 40, even if the speed limit is faster.
53. Time the lights.
Stoplights are sometimes timed for your motoring advantage; moving steadily at the speed limit will boost your chances of having the "green light" all the way.
54. Open up windows .
In stop-and-go traffic, shutting off the air conditioning and opening the windows can lighten your fuel use. Air conditioning can lower your fuel economy by 10 percent to 20 percent.
55. Turn it off.
You can save gas if you turn off you car while waiting at long traffic light sequences, railroad crossings or while your better half pulls money from the ATM. If you are not moving for more then 30 seconds, you should turn off the engine. For every hour you're sitting at idle, you're probably burning a gallon of gasoline.
Tips to Save Gas During Highway Driving
56. Keep windows closed. Keep windows closed when traveling at highway speeds. Open windows cause air drag, reducing your mileage by 10%.
57. Cruise along.
If you have a cruise control and there isn't a whole lot of traffic, you probably should use it (it will keep the speed constant and hence doesn't need to accelerate).
58. Overdrive.
Use the overdrive gears, as this will generally keep your RPM down and your wallet happy(er).
59. Kill the AC.
Using the air conditioning drinks gas - consider turning it off 5 minutes before you reach your destination. You will still stay cool for the duration of your trip, but will save gas from not having it blasting until the last second.
Ways to Save Gas During Shutdown
60. No revs. Avoid "revving" the engine as you switch the engine off.
61. Forward only.
Park your car so that you can later begin to travel in forward gear; avoiding reverse gear maneuvers will save gas.
62. Go for the shade.
The hot summer sun makes the inside of your car feel like a sauna; when you get moving you will want to cool it down, either through rolling down the windows or using the AC. Parking your vehicle in the shade will help keep it cool when you start up again.
63. Use the garage.
Clear it out and make room for your car. Parking in your garage will help your car stay warm in winter and cool in summer, and you won't have to depend as much on your gas-guzzling air-conditioning or defroster when you drive.
64. Window prep.
In the summer, roll down the windows just a tiny bit so the air can circulate through your car while you are parked. This will help keep it cool when you start up again.
65. Park and walk.
If you wander all over the parking lot looking for that really close parking space, you'll use more gas. Don't be afraid to walk a ways--it might do you good. With gas prices on the rise, make the system work for you.
Save More Gas After the Trip Has Ended
66. Make a Log
After your trip, make a journal entry on the 'mileage victories' and 'mileage failures' of your trip.
Examples of these might be:
"Drove into the North End of Boston at 4PM. Ended up caught in gridlock, and couldn't find parking for 45 minutes. Stupid, stupid, stupid - never again!"
"Drove 12 miles to the hardware store only to find that they were out of lawn chairs. Should have called first."
"Left 10 minutes early to do the daycare pickup - Wow! No traffic on the major artery, and caught every green light. Will try this every day."
Cars & Transportation (cars)
While the rising cost of oil has the price of gasoline skyrocketing faster than global warming is melting glaciers, people everywhere are preparing for cross-country road trips to Grand Canyon National Park and summer camps in Maine. We can't really argue with that innate desire to get closer to nature and out on the open road, and whether you're a die-hard cyclist or a still driving an SUV, chances are you plan to get in a car to go somewhere this summer. So whether you're packing up the Prius for some close-to-home camping, towing the boat to far-away shores, or merely fighting the crosstown traffic, these money- and gas-saving tips are designed to help you squeeze every last bit of power out of that precious petrol--and cause fewer CO2 emissions, too. It's a comprehensive list--several tasks should be done before even starting your car; others require minor adjustments to your driving style. All of them aim to help you drive a little greener.
Gas-Saving Tips: Questions to Ask Before You Turn on the Engine
1. Is your engine tuned up? Fixing a car that is out of tune (or has failed an emissions test) will boost gas mileage, so be sure to give your car regular tune-ups. You'll also want to watch out for worn spark plugs. A misfiring spark plug can dramatically reduce a car's fuel efficiency.
2. Is your body in good shape?
Inspect suspension and chassis parts for occasional misalignment. Bent wheels, axles, bad shocks, broken springs, et cetera create engine drag and are unsafe at high traveling speeds.
3. Is your air filter clean?
When the engine air filter clogs with dirt, dust and bugs, it causes your engine to work harder and your car becomes less fuel-efficient. Replacing a clogged air filter could improve your gas mileage by as much as 10 percent. It's a good idea to have your engine air filter checked at each oil change.
4. What grade is your oil?
You can improve your car's gas mileage by using the manufacturer's recommended grade of motor oil. Opt for motor oil with the words "energy conserving" on the API performance label; this oil contains friction-reducing additives.
5. Got shade?
Buy a good windshield shade. A windshield shade blocks sunlight and helps to keep heat out of the inside of your car. This will help reduce air conditioning use in the summer.
Ways to Save Money on Gas at the Pump
6. Don't overfill 'er up. Avoid filling your gas tank to the top. Overfilling results in sloshing over and out of tank. Never fill gas tank past the first "click" of fuel nozzle if the nozzle is automatic.
7. Use the lowest octane you can.
Buy the lowest grade or octane of gasoline that is appropriate for your car; pricey premium fuel won't boost your car's fuel economy.
8. Tighten that cap.
Gas will evaporate from your car's gas tank if it has an escape. Loose, missing, or damaged gas caps cause millions of gallons of gas to evaporate each year.
9. Wait until you're near empty.
Don't fill up until your tank is near empty; this will extend your gas because you are hauling a lighter load as the tank nears empty.
10. Find credit card discounts.
Some credit cards offer gas savings when you use the card for purchases. This works in much the same way that some credit card companies give you frequent-flier miles when you use their card for purchases.
11. Membership has its privileges.
Some gas stations offer membership benefits. There are also department and grocery stores that give discounts at the fuel pump when you use their store membership cards.
12. Screw the brand names.
Brand means nothing in the gas world; they are all using the same refineries, trucks, and pipelines to transport the fuel. Go for cost savings when it comes to the price of gas.
13. Keep your eyes on the prize.
Scope out gas prices while you're driving (but keep your eyes on the road, Smokey.) Some gas stations offer free coffee with fill up as well. And if it's not shade-grown and organic? Meh...live a little.
14. Don't get desperate.
The first gas station you encounter after a long thirsty stretch will never be the cheapest - drive a little further to find a cheaper station.
15. In the city, don't shop around.
Don't price shop for gas locally by driving around, the miles you drive will almost certainly eliminate the savings, and stop-and-go city traffic does a number on your average efficiency, not to mention your greenhouse gas emissions.
16. Exit, stage left. On the highway, that is.
On the highway, take an exit at a moderately sized city and head for the city center. There will likely be several stations near the ramp with cheaper gas.
record_gas_prices.jpg
More Ways to Save Gas: Things to Check Before You Get on the Road
17. Are they open? Is the place you are going to open for business? Shops often have irregular hours, especially at nights and on the weekends. Always, always, always call or go online first!
18. Do you know where you are going?
Have you confirmed that the address you are given actually exists and is accurate? IF not, you could be wasting fuel and time on miles being lost.
19. Did you do your due diligence?
Use the Interwebz, newspapers, or phone book to comparison shop before you drive around to several stores.
20. Do they have what you want?
Restaurants often have long waits, products can be out of stock, and so on. Confirm that the place you're headed can deliver the goods before you get there.
21. Can it be delivered?
Find companies willing to delivery what you need to your home. Amazon, dry cleaning delivery services, food, and anything else that will bring what you need without burning up your gas may save some loot and the planet some warming.
22. Do you have to go right now?
Traveling in off-peak times will reduce your time spent in traffic, waiting for lights, etc.
23. Can you combine trips?
Combine errands into one trip and plan your stops for the most efficient route. You'll save yourself time and money.
Ways to Save Gas and Money: Are You Using Your Vehicle Wisely?
24. Could you walk or bike? Just burn calories, man. Pay attention to why, where, and when you drive.
25. Is there a public transportation option available?
Look into public transportation; after you figure in driving around for parking and such, it may actually be faster.
26. Should you get a rental car?
A small car almost always has a better fuel economy due to its smaller mass; in certain situations you may want to rent a smaller vehicle for the trip instead of using your own. (Conversely, you can also choose to buy a smaller car from the get-go, and rent a larger one only when necessary.)
27. Did you maximize the square footage of your vehicle?
For human cargo, carpools reduce travel monotony and gas expense--all riders chip in to help you buy. Carpooling also reduces traffic congestion, gives the driver easier maneuverability and greater "steady speed" economy. If you're hauling materials such as wood, fill the whole vehicle on each trip.
How to Save Gas by Planning Your Route
28. No rough stuff. Riding on dirt or gravel will rob you of up to 30% of your gas mileage.
29. Use alternate roads when safer, shorter, and straighter.
Compare traveling distance differences--remember that corners, curves and lane jumping requires extra gas. The shortest distance between two points is always straight as the crow flies.
30. Avoid heavy traffic and lots of traffic lights.
The shortest route is not always the most fuel efficient if you have to stop a lot.
Getting Ready for Takeoff
31. Are your tires fat or flat? Proper tire pressure will give you better gas mileage. Inflate all tires to maximum limit; each tire should also be periodically spun, balanced and checked for out-of-roundness.
32. Lose the top.
Remove vinyl tops, they cause air drag.
33. Lose the racks.
Remove ski, bicycle, or luggage racks from your roof if you don't need it. They also cause air drag.
34. Drop the rest of the dead weight.
Get rid of all extra tires, back seats, unnecessary heavy parts. Extra weight reduces mileage, especially when driving up inclines.
35. Trucks, drop the tailgate.
You will get more mileage if you put down the tailgate due to less wind resistance.
36. Use your GPS.
A GPS unit will pay for itself in wasted time and gas very quickly.
How To Save Gas During Engine Startup
37. Turn off electronics. Starting your car with electronic devices, like the radio, air conditioning, and 12-volt refrigerator turned off will put less strain on your engine which translates to better gas mileages.
38. Close the sun or moon roof.
Having these open will increase drag.
39. Turn the key and get moving.
Modern vehicles do not need to be warmed up, even on cold mornings - 30 seconds is plenty of time.
40. Turn off the choke.
If the car is revving, check that the automatic choke is disengaged after engine warm up.
41. Check for leaks.
Before you take your car out, check the driveway for gas tank leaks. Even little ones can waste plenty of fuel over time.
Ways to Save Gas While On The Road
42. Drive steadily.Slowing down or speeding up wastes fuel. Maintain a steady pace--the ideal trip is one where you never stop except for signs and lights.
43. Don't exceed the legal speed limit.
However tough it may be to comprehend, the primarily goal of a speed limit for your traveling safety. However, it is also a good estimate of the most efficient speed for the road as well.
44. Careful with those brakes.
A car consumes the most gas as it accelerates, while a moving car doesn't require much gasoline to keep moving. Ideally, the brake should be used sparingly--expert hypermilers roll to a dead stop at every red light and stop sign.
45. Shift up early and down late.
If you have a manual transmission and want to save some gas, here's a hot tip: You need to shift up as soon as you can and shift down as the last possible moment.
46. Avoid hard stops.
Panic or hard stops will also cost you; anticipate stop signs, pedestrian walkways, and traffic lights.
47. Get on the good foot: Use your right one only.
To avoid riding the brake and wasting gas, use your right foot to control both pedals.
48. Don't weave.
The more you weave the more gas you burn. Keep your wheel still and steady as she goes.
49. Don't accelerate up hill.
Don’t accelerate up a hill. When approaching it, build up speed before the incline, maintain on the way up, then coast down.
50. Follow traffic reports.
The radio is the road's information superhighway, and traffic reports are there for a reason. Use them to avoid jams and other delays, which can help keep your momentum steady.
How To Save Gas During City Driving
51. Eliminate jack-rabbit starts. Always accelerate slowly when starting from a dead stop. A good rule of thumb is to not push the pedal down more than 1/4 of the total foot travel.
52. Beat the Wind.
Exceeding 40 mph forces your auto to overcome tremendous wind resistance, which will dramatically decrease your mileage. Try and keep it under 40, even if the speed limit is faster.
53. Time the lights.
Stoplights are sometimes timed for your motoring advantage; moving steadily at the speed limit will boost your chances of having the "green light" all the way.
54. Open up windows .
In stop-and-go traffic, shutting off the air conditioning and opening the windows can lighten your fuel use. Air conditioning can lower your fuel economy by 10 percent to 20 percent.
55. Turn it off.
You can save gas if you turn off you car while waiting at long traffic light sequences, railroad crossings or while your better half pulls money from the ATM. If you are not moving for more then 30 seconds, you should turn off the engine. For every hour you're sitting at idle, you're probably burning a gallon of gasoline.
Tips to Save Gas During Highway Driving
56. Keep windows closed. Keep windows closed when traveling at highway speeds. Open windows cause air drag, reducing your mileage by 10%.
57. Cruise along.
If you have a cruise control and there isn't a whole lot of traffic, you probably should use it (it will keep the speed constant and hence doesn't need to accelerate).
58. Overdrive.
Use the overdrive gears, as this will generally keep your RPM down and your wallet happy(er).
59. Kill the AC.
Using the air conditioning drinks gas - consider turning it off 5 minutes before you reach your destination. You will still stay cool for the duration of your trip, but will save gas from not having it blasting until the last second.
Ways to Save Gas During Shutdown
60. No revs. Avoid "revving" the engine as you switch the engine off.
61. Forward only.
Park your car so that you can later begin to travel in forward gear; avoiding reverse gear maneuvers will save gas.
62. Go for the shade.
The hot summer sun makes the inside of your car feel like a sauna; when you get moving you will want to cool it down, either through rolling down the windows or using the AC. Parking your vehicle in the shade will help keep it cool when you start up again.
63. Use the garage.
Clear it out and make room for your car. Parking in your garage will help your car stay warm in winter and cool in summer, and you won't have to depend as much on your gas-guzzling air-conditioning or defroster when you drive.
64. Window prep.
In the summer, roll down the windows just a tiny bit so the air can circulate through your car while you are parked. This will help keep it cool when you start up again.
65. Park and walk.
If you wander all over the parking lot looking for that really close parking space, you'll use more gas. Don't be afraid to walk a ways--it might do you good. With gas prices on the rise, make the system work for you.
Save More Gas After the Trip Has Ended
66. Make a Log
After your trip, make a journal entry on the 'mileage victories' and 'mileage failures' of your trip.
Examples of these might be:
"Drove into the North End of Boston at 4PM. Ended up caught in gridlock, and couldn't find parking for 45 minutes. Stupid, stupid, stupid - never again!"
"Drove 12 miles to the hardware store only to find that they were out of lawn chairs. Should have called first."
"Left 10 minutes early to do the daycare pickup - Wow! No traffic on the major artery, and caught every green light. Will try this every day."
Friday, December 7, 2007
Are There Really 'Continents' of Floating Garbage?
Galaxy
12/7/07
Since stories have started surfacing more recently, many have wondered, if the rumors are true. Are there really 'continents', or massive floating garbage patches residing in the pacific ocean? Apparently, the rumors are true, and these unsightly patches are reportedly killing marine life and releasing poisons that enter the human food chain, as well. However, before you start imagining a plastic version of Maui, keep in mind that these plastic patches certainly aren'tsolid surfaced islands that you could build a house on! Ocean currents have collected massive amounts of garbage into a sort of plastic "soup" where countless bits of discarded plastic float intertwined just beneath the surface. Indeed, the human race has really made its mark. One enormous plastic patch is estimated to weigh over 3 million tons altogether and cover an area roughly twice the size of Texas.
But if there is an unfathomably massive collection of plastic junk out there, then why doesn't everyone already know about it, and why aren't we doing something about it? Well, there are several reasons. First, no one is keen to claim responsibility for these monstrosities, which exists in one of the most remote spots on the planet. It's easier to ignore than to deal with, at least in the short term. Most of the
plastic is floating just below the surface where explorers, researchers, and scientists can get a good close-up view, but it is nearly impossible to see the massive quantities of submerged trash in photographs taken from great distances. This makes it easier for naysayers to disregard the problem as a mere myth, in spite of all of the well-documented research to the contrary. Clean up seems nearly impossible at this point, so even those who are well aware of the situation have adopted the famous ostrich cliche of burying their heads in the sand. Even so, this polluted, chemical filled junk is finding it's way onto our dinner tables.
Sadly, marine researcher Charles Moore at the Algalita Marina Research Foundation in Long Beach says there’s no practical fix for the problem. He has been studying the massive patch for the past 10 years, and said the debris is to the point where it would be nearly impossible to extract.
"Any attempt to remove that much plastic from the oceans - it boggles the mind," Moore said from Hawaii, where his crew is docked. "There's just too much, and the ocean is just too big."
The trash collects in this remote area, known as the North Pacific Gyre, due to a clockwise trade wind that encircles the Pacific Rim. According to Moore the trash accumulates the same way bubbles clump at the center of hot tub.
Ian Kiernan, the Australian founder of Clean Up the World, started his environmental campaign two decades ago after being shocked by the incredible amount of rubbish he saw on an around-the-world solo yacht race. He'll says he’ll never be able the wipe the atrocious site from his memory.
"It was just filled with things like furniture, fridges, plastic containers, cigarette lighters, plastic bottles, light globes, televisions and fishing nets," Kiernan says. "It's all so durable it floats. It's just a major problem."
Kiernan says it’s killing wildlife in a vicious cycle. Holding an ashtray filled with colorful pieces of plastic he told The Sydney Morning Herald, "this is the contents of a fleshy-footed shearwater's stomach. They go to the ocean to fish but there ain't no fish - there's plastic. They then regurgitate it down the necks of their fledglings and it kills them. After the birds decompose, the plastic gets washed back into the ocean where it can kill again. It's a form of ghost fishing, where it goes on and on."
A Dutch study in the North Sea of fulmar seabirds concluded 95 per cent of the birds had plastic in their stomachs. More than 1600 pieces were found in the stomach of one bird in Belgium.
The United Nations Environment Program says plastic is accountable for the deaths of more than a million seabirds and more than 100,000 marine mammals such as whales, dolphins and seals every year.
Since his first encounter with the gyre in 1997, Moore created the Algalita Marine Research Foundation to help study the problem. Canadian filmmaker Ian Connacher joined Moore last year to film the garbage patch for his documentary, I Am Plastic.
"The most menacing part is those little bits of plastic start looking like food for certain animals, or the filter feeders don't have any choice, they just pick them up," noted Connacher.
Perhaps an even bigger problem is hiding beneath the surface of the islands of garbage. Greenpeace reports that about 70 per cent of the plastic that makes it to the ocean sinks to the bottom, where it then smothers marine life on the ocean floor. Dutch scientists have found 600,000 tons of discarded plastic on the bottom of the North Sea alone.
A study by the Japanese geochemist Hideshige Takada and his colleagues at Tokyo University in 2001 found that plastic polymers soak up the resilient poisons such as DDT and polychlorinated biphenyls. The researchers found that non-water-soluble toxic chemicals can be found in plastic in levels as high as a million times their concentration in water. As small pieces of plastic are mistaken for fish eggs and other food by marine life, these toxins end up at the dinner table. But even without the extra toxins, eating plastic is hazardous to health.
It is estimated that 80 per cent of plastic found at sea is washed out from the land. The journal Science last year predicted seafood stocks would collapse by 2048 if overfishing and pollution continued. If the seafood stocks collapse, a lot of humans will follow. So, is there anything we can do to prevent this?
Greenpeace says embracing the three Rs - reduce, re-use and recycle - would help tackle the problem. Plastic recycling is lagging well behind paper and cardboard. Part of the reason is because many people aren’t even sure what recycling options exist in their area. But there are other challenges for plastic recycling too. Some plastics release toxic chemicals into the atmosphere, and are more expensive to recycle than to simply create a new product from petrochemicals.
The widespread use of bioplastics could largely reduce the amount of plastic strewn around the world. Traditional petrochemical-based plastics are non-degradable and non-renewable; degradable plastic breaks into smaller pieces in UV light but remains plastic. Then there are two kinds of biodegradable plastic that break down in compost - one from a petrochemical resource, the other from a renewable resource such as corn or wheat, which is known as bioplastic. Bioplastic is by far the most environmentally friendly option. Dr Katherine Dean, of the CSIRO, says corporate firms are now becoming increasingly interested in bioplastics.
"When oil prices soared in 2005, that changed a lot of people's perspective, because bioplastic became quite cost-competitive," she says. "All of a sudden it wasn't just about doing the right thing."
The company Plantic Technologies, has developed biodegradable plastic for everything from food and beverage packaging to medical, agricultural and sporting applications. The chief executive of Plantic, Grant Dow, says once composted, the plastic would become nothing more than carbon dioxide and water.
"For all intents and purposes, it looks like plastic and feels like plastic and does the same thing as plastic in the application," he says.
"It will only biodegrade in the presence of heat, moisture and bacteria, so it will sit in your cupboard pretty much indefinitely, but when the bacteria get to it in compost, that's it. It's gone."
While parts of our oceans have already become inhospitable soups of plastic and plankton, we can at least mitigate the future consequences by making smart individual choices. Experts say the best way to mitigate the damage down the road is by buying less products that contain plastics or plastic packaging, recycling, lobbying for safer bio-degradable plastics, and by purchasing reusable cloth grocery bags among other strategies.
12/7/07
Since stories have started surfacing more recently, many have wondered, if the rumors are true. Are there really 'continents', or massive floating garbage patches residing in the pacific ocean? Apparently, the rumors are true, and these unsightly patches are reportedly killing marine life and releasing poisons that enter the human food chain, as well. However, before you start imagining a plastic version of Maui, keep in mind that these plastic patches certainly aren'tsolid surfaced islands that you could build a house on! Ocean currents have collected massive amounts of garbage into a sort of plastic "soup" where countless bits of discarded plastic float intertwined just beneath the surface. Indeed, the human race has really made its mark. One enormous plastic patch is estimated to weigh over 3 million tons altogether and cover an area roughly twice the size of Texas.
But if there is an unfathomably massive collection of plastic junk out there, then why doesn't everyone already know about it, and why aren't we doing something about it? Well, there are several reasons. First, no one is keen to claim responsibility for these monstrosities, which exists in one of the most remote spots on the planet. It's easier to ignore than to deal with, at least in the short term. Most of the
plastic is floating just below the surface where explorers, researchers, and scientists can get a good close-up view, but it is nearly impossible to see the massive quantities of submerged trash in photographs taken from great distances. This makes it easier for naysayers to disregard the problem as a mere myth, in spite of all of the well-documented research to the contrary. Clean up seems nearly impossible at this point, so even those who are well aware of the situation have adopted the famous ostrich cliche of burying their heads in the sand. Even so, this polluted, chemical filled junk is finding it's way onto our dinner tables.
Sadly, marine researcher Charles Moore at the Algalita Marina Research Foundation in Long Beach says there’s no practical fix for the problem. He has been studying the massive patch for the past 10 years, and said the debris is to the point where it would be nearly impossible to extract.
"Any attempt to remove that much plastic from the oceans - it boggles the mind," Moore said from Hawaii, where his crew is docked. "There's just too much, and the ocean is just too big."
The trash collects in this remote area, known as the North Pacific Gyre, due to a clockwise trade wind that encircles the Pacific Rim. According to Moore the trash accumulates the same way bubbles clump at the center of hot tub.
Ian Kiernan, the Australian founder of Clean Up the World, started his environmental campaign two decades ago after being shocked by the incredible amount of rubbish he saw on an around-the-world solo yacht race. He'll says he’ll never be able the wipe the atrocious site from his memory.
"It was just filled with things like furniture, fridges, plastic containers, cigarette lighters, plastic bottles, light globes, televisions and fishing nets," Kiernan says. "It's all so durable it floats. It's just a major problem."
Kiernan says it’s killing wildlife in a vicious cycle. Holding an ashtray filled with colorful pieces of plastic he told The Sydney Morning Herald, "this is the contents of a fleshy-footed shearwater's stomach. They go to the ocean to fish but there ain't no fish - there's plastic. They then regurgitate it down the necks of their fledglings and it kills them. After the birds decompose, the plastic gets washed back into the ocean where it can kill again. It's a form of ghost fishing, where it goes on and on."
A Dutch study in the North Sea of fulmar seabirds concluded 95 per cent of the birds had plastic in their stomachs. More than 1600 pieces were found in the stomach of one bird in Belgium.
The United Nations Environment Program says plastic is accountable for the deaths of more than a million seabirds and more than 100,000 marine mammals such as whales, dolphins and seals every year.
Since his first encounter with the gyre in 1997, Moore created the Algalita Marine Research Foundation to help study the problem. Canadian filmmaker Ian Connacher joined Moore last year to film the garbage patch for his documentary, I Am Plastic.
"The most menacing part is those little bits of plastic start looking like food for certain animals, or the filter feeders don't have any choice, they just pick them up," noted Connacher.
Perhaps an even bigger problem is hiding beneath the surface of the islands of garbage. Greenpeace reports that about 70 per cent of the plastic that makes it to the ocean sinks to the bottom, where it then smothers marine life on the ocean floor. Dutch scientists have found 600,000 tons of discarded plastic on the bottom of the North Sea alone.
A study by the Japanese geochemist Hideshige Takada and his colleagues at Tokyo University in 2001 found that plastic polymers soak up the resilient poisons such as DDT and polychlorinated biphenyls. The researchers found that non-water-soluble toxic chemicals can be found in plastic in levels as high as a million times their concentration in water. As small pieces of plastic are mistaken for fish eggs and other food by marine life, these toxins end up at the dinner table. But even without the extra toxins, eating plastic is hazardous to health.
It is estimated that 80 per cent of plastic found at sea is washed out from the land. The journal Science last year predicted seafood stocks would collapse by 2048 if overfishing and pollution continued. If the seafood stocks collapse, a lot of humans will follow. So, is there anything we can do to prevent this?
Greenpeace says embracing the three Rs - reduce, re-use and recycle - would help tackle the problem. Plastic recycling is lagging well behind paper and cardboard. Part of the reason is because many people aren’t even sure what recycling options exist in their area. But there are other challenges for plastic recycling too. Some plastics release toxic chemicals into the atmosphere, and are more expensive to recycle than to simply create a new product from petrochemicals.
The widespread use of bioplastics could largely reduce the amount of plastic strewn around the world. Traditional petrochemical-based plastics are non-degradable and non-renewable; degradable plastic breaks into smaller pieces in UV light but remains plastic. Then there are two kinds of biodegradable plastic that break down in compost - one from a petrochemical resource, the other from a renewable resource such as corn or wheat, which is known as bioplastic. Bioplastic is by far the most environmentally friendly option. Dr Katherine Dean, of the CSIRO, says corporate firms are now becoming increasingly interested in bioplastics.
"When oil prices soared in 2005, that changed a lot of people's perspective, because bioplastic became quite cost-competitive," she says. "All of a sudden it wasn't just about doing the right thing."
The company Plantic Technologies, has developed biodegradable plastic for everything from food and beverage packaging to medical, agricultural and sporting applications. The chief executive of Plantic, Grant Dow, says once composted, the plastic would become nothing more than carbon dioxide and water.
"For all intents and purposes, it looks like plastic and feels like plastic and does the same thing as plastic in the application," he says.
"It will only biodegrade in the presence of heat, moisture and bacteria, so it will sit in your cupboard pretty much indefinitely, but when the bacteria get to it in compost, that's it. It's gone."
While parts of our oceans have already become inhospitable soups of plastic and plankton, we can at least mitigate the future consequences by making smart individual choices. Experts say the best way to mitigate the damage down the road is by buying less products that contain plastics or plastic packaging, recycling, lobbying for safer bio-degradable plastics, and by purchasing reusable cloth grocery bags among other strategies.
Thursday, September 13, 2007
Green Basics: Organic Food
by Collin Dunn, Seattle on 09.13.07
Food & Health
Though known colloquially as food that is grown more healthily (and is more expensive), in order for organic food to be certified as such, it must be produced under specific, legally-regulated standards and be subject to testing in order to retain certification.
In agriculture, this means that crops were grown without the use of conventional pesticides, artificial fertilizers or sewage sludge, and that they were processed without food additives (like chemical preservatives). When it comes to animals, they must be reared without the routine use of antibiotics and growth hormones and fed a diet of organic foods. In most countries, organic produce must not be genetically modified.
Historically, organic produce was almost exclusively available directly from small family-run farms or at community farmer's markets. Lately, though, organic foods are becoming much more widely available; organic food sales in the United States have grown by 17 to 20 percent a year for the past few years, while sales of conventional food have grown more slowly, at about 2 to 3 percent a year. This explosion in popularity has led the way for bigger companies, like Wal-Mart, to get into the organic food business and change the way that organics are perceived and, to a certain extent, the way they're produced.
Perhaps the most important thing to understand about organic food is the relationship between legal (usually government) oversight and production of food employing earth-friendly practices. In order to be "certified," organic food -- and the farm it was grown on -- must apply for certification, pass a rigorous series of tests, and pay a fee for the process. In the US, this process is regulated by the US Department of Agriculture; as a government agency, it's subject to politicization and changing rules as different administrations and individuals assert their influence. As such, all "certified" organic food is organic, but not all organic food is certified. This, in part, has led to the increasing popularity of local food over organic food (but that's another post).
As organics have grown in popularity, more and more food items are available in organic varieties. What used to be the nearly exclusive realm of fruits and vegetables has grown to include processed foods like coffee (though its days may be numbered), ketchup and ice cream -- a veritable orgy of organic food that has come to include just about anything and everything you eat on a daily basis. The modulation of the market to include more processed foods marks a sea change in the organic industry, though, as these processed foods are increasingly coming from large conglomerates and companies producing huge amounts of canned goods, frozen vegetables, pre-prepared dishes and the like. While the ingredients are certified, this "industrialization of organic" down conveyor belts and into a carbon-intensive supply chain is a bit antithetical to organics' original purpose of creating "an ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity. It is based on minimal use of off-farm inputs and on management practices that restore, maintain and enhance ecological harmony", as defined by the USDA National Organic Standards Board.
Still, the only way to be sure that the food you're eating is organic, short of growing it yourself (or buying it from someone you trust not to have soaked it in pesticides), is looking for certification marks, like the USDA Organic Seal, pictured here. Elsewhere, similar government regulations and third-party inspectors certify that food is produced to certain standards; in Australia, it's the NASAA Organic Standards, in Japan, the JAS Standards must be met. In the United States, In the United States, the Organic Food Production Act of 1990 (7 U.S.C.A. § 6501-22) required that the USDA develop national standards for organic products. The regulations (7 C.F.R. Part 205) are enforced by the USDA through the National Organic Program under this act. These laws essentially require that any product that claims to be organic must have been manufactured and handled according to specific NOP requirements. A USDA Organic seal identifies products with at least 95% organic ingredients.
Given the industrialization of organics and various attempts to water down organic standards, there are some widely agreed-upon benefits of organic farming, including things like: organic farms do not release synthetic pesticides into the environment, some of which have the potential to harm local wildlife; organic farms are better than conventional farms at sustaining diverse ecosystems, i.e., populations of plants and insects, as well as animals; and when calculated either per unit area or per unit of yield, organic farms use less energy and produce less waste, e.g., waste such as packaging materials for chemicals.
Further, a 2002 study found that "Organically grown foods consistently had about one-third as many residues as conventionally grown foods"; additionally, several studies corroborate this finding by having found that that while 77 percent of conventional food carries synthetic pesticide residues, only about 25 percent of organic food does. So, generally, organic food isn't going to have as much nasty residue on it, and that is a very good thing.
But what about taste? A 2001 study by researchers at Washington State University concluded that organic apples were sweeter. Along with taste and sweetness, the texture and firmness of the apples were also rated higher than those grown conventionally. These differences are attributed to the greater soil quality resulting from organic farming techniques compared to those of conventional farming. However, a different small study looking at processed organic foods found participants could not differentiate organic and conventional varieties of a rice cakes.
The biggest criticism of organic food, though, is the price premium. According to the Journal of Food Science, organic products typically cost 10 to 40% more than similar, conventionally-produced products. Prices tend to be higher because organic produce is produced on a smaller scale, and may need to be milled or processed separately; some of the price premium is likely to decrease as organic produce continues to scale up. Organic foods also tend to include more of the environmental costs that conventional agriculture tends to externalize. So, you're paying more for what's not in your food (pesticides, hormones, etc.) and you're paying more of the actual cost of food production, because things like pesticides aren't being passed along to the environment where friendly fuzzy bunnies and clear-running spring water pay for them.
For more information on organics, see Wikipedia's organic food entry, along with their organic farming entry. Local Harvest has more info on the different "shades" of organic you're likely to find at your local farmer's markets, while the USDA's National Organic Program and Alternative Farming Information Center will provide all the facts and definitions for organics (and give you some idea of the government's role in all of this).
Here at TreeHugger, we've written a lot about organics; we think organic milk is healthier, know that organics make the supply chain healthier, like to support new organic farms, take note when Wal-Mart and Safeway start incorporating organics, and believe that organic ketchup helps prevent cancer -- really! Read more in our How to Green Your Meals guide, or just type "organic" into our search engine and go nuts!
The Green Basics series of posts appears on Thursdays here at TreeHugger; we're writing them to provide basic information about important ideas, materials and technologies for new greenies, or for those who just need a quick refresher.
Food & Health
Though known colloquially as food that is grown more healthily (and is more expensive), in order for organic food to be certified as such, it must be produced under specific, legally-regulated standards and be subject to testing in order to retain certification.
In agriculture, this means that crops were grown without the use of conventional pesticides, artificial fertilizers or sewage sludge, and that they were processed without food additives (like chemical preservatives). When it comes to animals, they must be reared without the routine use of antibiotics and growth hormones and fed a diet of organic foods. In most countries, organic produce must not be genetically modified.
Historically, organic produce was almost exclusively available directly from small family-run farms or at community farmer's markets. Lately, though, organic foods are becoming much more widely available; organic food sales in the United States have grown by 17 to 20 percent a year for the past few years, while sales of conventional food have grown more slowly, at about 2 to 3 percent a year. This explosion in popularity has led the way for bigger companies, like Wal-Mart, to get into the organic food business and change the way that organics are perceived and, to a certain extent, the way they're produced.
Perhaps the most important thing to understand about organic food is the relationship between legal (usually government) oversight and production of food employing earth-friendly practices. In order to be "certified," organic food -- and the farm it was grown on -- must apply for certification, pass a rigorous series of tests, and pay a fee for the process. In the US, this process is regulated by the US Department of Agriculture; as a government agency, it's subject to politicization and changing rules as different administrations and individuals assert their influence. As such, all "certified" organic food is organic, but not all organic food is certified. This, in part, has led to the increasing popularity of local food over organic food (but that's another post).
As organics have grown in popularity, more and more food items are available in organic varieties. What used to be the nearly exclusive realm of fruits and vegetables has grown to include processed foods like coffee (though its days may be numbered), ketchup and ice cream -- a veritable orgy of organic food that has come to include just about anything and everything you eat on a daily basis. The modulation of the market to include more processed foods marks a sea change in the organic industry, though, as these processed foods are increasingly coming from large conglomerates and companies producing huge amounts of canned goods, frozen vegetables, pre-prepared dishes and the like. While the ingredients are certified, this "industrialization of organic" down conveyor belts and into a carbon-intensive supply chain is a bit antithetical to organics' original purpose of creating "an ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity. It is based on minimal use of off-farm inputs and on management practices that restore, maintain and enhance ecological harmony", as defined by the USDA National Organic Standards Board.
Still, the only way to be sure that the food you're eating is organic, short of growing it yourself (or buying it from someone you trust not to have soaked it in pesticides), is looking for certification marks, like the USDA Organic Seal, pictured here. Elsewhere, similar government regulations and third-party inspectors certify that food is produced to certain standards; in Australia, it's the NASAA Organic Standards, in Japan, the JAS Standards must be met. In the United States, In the United States, the Organic Food Production Act of 1990 (7 U.S.C.A. § 6501-22) required that the USDA develop national standards for organic products. The regulations (7 C.F.R. Part 205) are enforced by the USDA through the National Organic Program under this act. These laws essentially require that any product that claims to be organic must have been manufactured and handled according to specific NOP requirements. A USDA Organic seal identifies products with at least 95% organic ingredients.
Given the industrialization of organics and various attempts to water down organic standards, there are some widely agreed-upon benefits of organic farming, including things like: organic farms do not release synthetic pesticides into the environment, some of which have the potential to harm local wildlife; organic farms are better than conventional farms at sustaining diverse ecosystems, i.e., populations of plants and insects, as well as animals; and when calculated either per unit area or per unit of yield, organic farms use less energy and produce less waste, e.g., waste such as packaging materials for chemicals.
Further, a 2002 study found that "Organically grown foods consistently had about one-third as many residues as conventionally grown foods"; additionally, several studies corroborate this finding by having found that that while 77 percent of conventional food carries synthetic pesticide residues, only about 25 percent of organic food does. So, generally, organic food isn't going to have as much nasty residue on it, and that is a very good thing.
But what about taste? A 2001 study by researchers at Washington State University concluded that organic apples were sweeter. Along with taste and sweetness, the texture and firmness of the apples were also rated higher than those grown conventionally. These differences are attributed to the greater soil quality resulting from organic farming techniques compared to those of conventional farming. However, a different small study looking at processed organic foods found participants could not differentiate organic and conventional varieties of a rice cakes.
The biggest criticism of organic food, though, is the price premium. According to the Journal of Food Science, organic products typically cost 10 to 40% more than similar, conventionally-produced products. Prices tend to be higher because organic produce is produced on a smaller scale, and may need to be milled or processed separately; some of the price premium is likely to decrease as organic produce continues to scale up. Organic foods also tend to include more of the environmental costs that conventional agriculture tends to externalize. So, you're paying more for what's not in your food (pesticides, hormones, etc.) and you're paying more of the actual cost of food production, because things like pesticides aren't being passed along to the environment where friendly fuzzy bunnies and clear-running spring water pay for them.
For more information on organics, see Wikipedia's organic food entry, along with their organic farming entry. Local Harvest has more info on the different "shades" of organic you're likely to find at your local farmer's markets, while the USDA's National Organic Program and Alternative Farming Information Center will provide all the facts and definitions for organics (and give you some idea of the government's role in all of this).
Here at TreeHugger, we've written a lot about organics; we think organic milk is healthier, know that organics make the supply chain healthier, like to support new organic farms, take note when Wal-Mart and Safeway start incorporating organics, and believe that organic ketchup helps prevent cancer -- really! Read more in our How to Green Your Meals guide, or just type "organic" into our search engine and go nuts!
The Green Basics series of posts appears on Thursdays here at TreeHugger; we're writing them to provide basic information about important ideas, materials and technologies for new greenies, or for those who just need a quick refresher.
Thursday, July 19, 2007
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