What is the greenhouse effect, and is it affecting our climate?
The greenhouse effect is unquestionably real and helps to regulate the temperature of our planet. It is essential for life on Earth and is one of Earth's natural processes. It is the result of heat absorption by certain gases in the atmosphere (called greenhouse gases because they effectively 'trap' heat in the lower atmosphere) and re-radiation downward of some of that heat. Water vapor is the most abundant greenhouse gas, followed by carbon dioxide and other trace gases. Without a natural greenhouse effect, the temperature of the Earth would be about zero degrees F (-18°C) instead of its present 57°F (14°C). So, the concern is not with the fact that we have a greenhouse effect, but whether human activities are leading to an enhancement of the greenhouse effect.
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Are greenhouse gases increasing?
Human activity has been increasing the concentration of greenhouse gases in the atmosphere (mostly carbon dioxide from combustion of coal, oil, and gas; plus a few other trace gases). There is no scientific debate on this point. Pre-industrial levels of carbon dioxide (prior to the start of the Industrial Revolution) were about 280 parts per million by volume (ppmv), and current levels are about 370 ppmv. The concentration of CO2 in our atmosphere today, has not been exceeded in the last 420,000 years, and likely not in the last 20 million years. According to the IPCC Special Report on Emission Scenarios (SRES), by the end of the 21st century, we could expect to see carbon dioxide concentrations of anywhere from 490 to 1260 ppm (75-350% above the pre-industrial concentration).
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Is the climate warming?
Yes. Global surface temperatures have increased about 0.6°C (plus or minus 0.2°C) since the late-19th century, and about 0.4°F (0.2 to 0.3°C) over the past 25 years (the period with the most credible data). The warming has not been globally uniform. Some areas (including parts of the southeastern U.S.) have, in fact, cooled over the last century. The recent warmth has been greatest over North America and Eurasia between 40 and 70°N. Warming, assisted by the record El Niño of 1997-1998, has continued right up to the present, with 2001 being the second warmest year on record after 1998.
Linear trends can vary greatly depending on the period over which they are computed. Temperature trends in the lower troposphere (between about 2,500 and 26,000 ft.) from 1979 to the present, the period for which Satellite Microwave Sounding Unit data exist, are small and may be unrepresentative of longer term trends and trends closer to the surface. Furthermore, there are small unresolved differences between radiosonde and satellite observations of tropospheric temperatures, though both data sources show slight warming trends. If one calculates trends beginning with the commencement of radiosonde data in the 1950s, there is a slight greater warming in the record due to increases in the 1970s. There are statistical and physical reasons (e.g., short record lengths, the transient differential effects of volcanic activity and El Niño, and boundary layer effects) for expecting differences between recent trends in surface and lower tropospheric temperatures, but the exact causes for the differences are still under investigation (see National Research Council report "Reconciling Observations of Global Temperature Change").
An enhanced greenhouse effect is expected to cause cooling in higher parts of the atmosphere because the increased "blanketing" effect in the lower atmosphere holds in more heat, allowing less to reach the upper atmosphere. Cooling of the lower stratosphere (about 49,000-79,500ft.) since 1979 is shown by both satellite Microwave Sounding Unit and radiosonde data, but is larger in the radiosonde data.
Relatively cool surface and tropospheric temperatures, and a relatively warmer lower stratosphere, were observed in 1992 and 1993, following the 1991 eruption of Mt. Pinatubo. The warming reappeared in 1994. A dramatic global warming, at least partly associated with the record El Niño, took place in 1998. This warming episode is reflected from the surface to the top of the troposphere.
There has been a general, but not global, tendency toward reduced diurnal temperature range (DTR), (the difference between high and low daily temperatures) over about 50% of the global land mass since the middle of the 20th century. Cloud cover has increased in many of the areas with reduced diurnal temperature range. The overall positive trend for maximum daily temperature over the period of study (1950-93) is 0.1°C/decade, whereas the trend for daily minimum temperatures is 0.2°C/decade. This results in a negative trend in the DTR of -0.1°C/decade.
Indirect indicators of warming such as borehole temperatures, snow cover, and glacier recession data, are in substantial agreement with the more direct indicators of recent warmth. Evidence such as changes in glacier length is useful since it not only provides qualitative support for existing meteorological data, but glaciers often exist in places too remote to support meteorological stations, the records of glacial advance and retreat often extend back further than weather station records, and glaciers are usually at much higher alititudes that weather stations allowing us more insight into temperature changes higher in the atmosphere.
Large-scale measurements of sea-ice have only been possible since the satellite era, but through looking at a number of different satellite estimates, it has been determined that Arctic sea ice has decreased between 1973 and 1996 at a rate of -2.8 +/- 0.3%/decade. Although this seems to correspond to a general increase in temperature over the same period, there are lots of quasi-cyclic atmospheric dynamics (for example the Arctic Oscillation) which may also influence the extent and thickness of sea-ice in the Arctic. Sea-ice in the Antarctic has shown very little trend over the same period, or even a slight increase since 1979. Though extending the Antarctic sea-ice record back in time is more difficult due to the lack of direct observations in this part of the world.
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Are El Niños related to Global Warming?
El Niños are not caused by global warming. Clear evidence exists from a variety of sources (including archaeological studies) that El Niños have been present for hundreds, and some indicators suggest maybe millions, of years. However, it has been hypothesized that warmer global sea surface temperatures can enhance the El Niño phenomenon, and it is also true that El Niños have been more frequent and intense in recent decades. Recent climate model results that simulate the 21st century with increased greenhouse gases suggest that El Niño-like sea surface temperature patterns in the tropical Pacific are likely to be more persistent.
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Is the hydrological cycle (evaporation and precipitation) changing?
Overall, land precipitation for the globe has increased by ~2% since 1900, however, precipitation changes have been spatially variable over the last century. Instrumental records show that there has been a general increase in precipitation of about 0.5-1.0%/decade over land in northern mid-high latitudes, except in parts of eastern Russia. However, a decrease of about -0.3%/decade in precipitation has occurred during the 20th century over land in sub-tropical latitudes, though this trend has weakened in recent decades. Due to the difficulty in measuring precipitation, it has been important to constrain these observations by analyzing other related variables. The measured changes in precipitation are consistent with observed changes in streamflow, lake levels, and soil moisture (where data are available and have been analyzed).
Northern Hemisphere annual snow cover extent has consistently remained below average since 1987, and has decreased by about 10% since 1966. This is mostly due to a decrease in spring and summer snowfall over both the Eurasian and North American continents since the mid-1980s. However, winter and autumn snow cover extent has shown no significant trend for the northern hemisphere over the same period.
Improved satellite data shows that a general trend of increasing cloud amount over both land and ocean since the early 1980s, seems to have reversed in the early 1990s, and total cloud amount of land and ocean now appears to be decreasing. However, there are several studies that suggest regional cloudiness, perhaps especially in the thick precipitating clouds has increased over the 20th century.
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Is the atmospheric/oceanic circulation changing?
A rather abrupt change in the El Niño - Southern Oscillation behavior occurred around 1976/77 and the new regime has persisted. There have been relatively more frequent and presistent El Niño episodes rather than the cool La Niñas. This behavior is highly unusual in the last 120 years (the period of instrumental record). Changes in precipitation over the tropical Pacific are related to this change in the El Niño - Southern Oscillation, which has also affected the pattern and magnitude of surface temperatures. However, it is unclear as to whether this apparent change in the ENSO cycle is caused by global warming.
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Is the climate becoming more variable or extreme?
On a global scale there is little evidence of sustained trends in climate variability or extremes. This perhaps reflects inadequate data and a dearth of analyses. However, on regional scales, there is clear evidence of changes in variability or extremes.
In areas where a drought or excessive wetness usually accompanies an El Niño, these dry or wet spells have been more intense in recent years. Other than these areas, little evidence is available of changes in drought frequency or intensity.
In some areas where overall precipitation has increased (ie. the mid-high northern latitudes), there is evidence of increases in the heavy and extreme precipitation events. Even in areas such as eastern Asia, it has been found that extreme precipitation events have increased despite total precipitation remaining constant or even decreasing somewhat. This is related to a decrease in the frequency of precipitation in this region.
Many individual studies of various regions show that extra-tropical cyclone activity seems to have generally increased over the last half of the 20th century in the northern hemisphere, but decreased in the southern hemisphere. It is not clear whether these trends are multi-decadal fluctuations or part of a longer-term trend.
Where reliable data are available, tropical storm frequency and intensity show no significant long-term trend in any basin. There are apparent decadal-interdecadal fluctuations, but nothing which is conlusive in suggesting a longer-term component.
Global temperature extremes have been found to exhibit no significant trend in interannual variability, but several studies suggest a significant decrease in intra-annual variability. There has been a clear trend to fewer extremely low minimum temperatures in several widely-separated areas in recent decades. Widespread significant changes in extreme high temperature events have not been observed.
There is some indication of a decrease in day-to-day temperature variability in recent decades.
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How important are these changes in a longer-term context?
Paleoclimatic data are critical for enabling us to extend our knowledge of climatic variability beyond what is measured by modern instruments. Many natural phenomena are climate dependent (such as the growth rate of a tree for example), and as such, provide natural 'archives' of climate information. Some useful paleoclimate data can be found in sources as diverse as tree rings, ice cores, corals, lake sediments (including fossil insects and pollen data), speleothems (stalactites etc), and ocean sediments. Some of these, including ice cores and tree rings provide us also with a chronology due the nature of how they are formed, and so high resolution climate reconstruction is possible in these cases. However, there is not a comprehensive 'network' of paleoclimate data as there is with instrumental coverage, so global climate reconstructions are often difficult to obtain. Nevertheless, combining different types of paleoclimate records enables us to gain a near-global picture of climate changes in the past.
For the Northern Hemisphere summer temperature, recent decades appear to be the warmest since at least about 1000AD, and the warming since the late 19th century is unprecedented over the last 1000 years. Older data are insufficient to provide reliable hemispheric temperature estimates. Ice core data suggest that the 20th century has been warm in many parts of the globe, but also that the significance of the warming varies geographically, when viewed in the context of climate variations of the last millennium.
Large and rapid climatic changes affecting the atmospheric and oceanic circulation and temperature, and the hydrological cycle, occurred during the last ice age and during the transition towards the present Holocene period (which began about 10,000 years ago). Based on the incomplete evidence available, the projected change of 3 to 7°F (1.5 - 4°C) over the next century would be unprecedented in comparison with the best available records from the last several thousand years.
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Is sea level rising?
Global mean sea level has been rising at an average rate of 1 to 2 mm/year over the past 100 years, which is significantly larger than the rate averaged over the last several thousand years. Projected increase from 1990-2100 is anywhere from 0.09-0.88 meters, depending on which greenhouse gas scenario is used and many physical uncertainties in contributions to sea-level rise from a variety of frozen and unfrozen water sources.
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Can the observed changes be explained by natural variability, including changes in solar output?
Since our entire climate system is fundamentally driven by energy from the sun, it stands to reason that if the sun's energy output were to change, then so would the climate. Since the advent of space-borne measurements in the late 1970s, solar output has indeed been shown to vary. There appears to be confirmation of earlier suggestions of an 11 (and 22) year cycle of irradiance. With only 20 years of reliable measurements however, it is difficult to deduce a trend. But, from the short record we have so far, the trend in solar irradiance is estimated at ~0.09 W/m2 compared to 0.4 W/m2 from well-mixed greenhouse gases. There are many indications that the sun also has a longer-term variation which has potentially contributed to the century-scale forcing to a greater degree. There is though, a great deal of uncertainty in estimates of solar irradiance beyond what can be measured by satellites, and still the contribution of direct solar irradiance forcing is small compared to the greenhouse gas component. However, our understanding of the indirect effects of changes in solar output and feedbacks in the climate system is minimal. There is much need to refine our understanding of key natural forcing mechanisms of the climate, including solar irradiance changes, in order to reduce uncertainty in our projections of future climate change.
In addition to changes in energy from the sun itself, the Earth's position and orientation relative to the sun (our orbit) also varies slightly, thereby bringing us closer and further away from the sun in predictable cycles (called Milankovitch cycles). Variations in these cycles are believed to be the cause of Earth's ice-ages (glacials). Particularly important for the development of glacials is the radiation receipt at high northern latitudes. Diminishing radiation at these latitudes during the summer months would have enabled winter snow and ice cover to persist throughout the year, eventually leading to a permanent snow- or icepack. While Milankovitch cycles have tremendous value as a theory to explain ice-ages and long-term changes in the climate, they are unlikely to have very much impact on the decade-century timescale. Over several centuries, it may be possible to observe the effect of these orbital parameters, however for the prediction of climate change in the 21st century, these changes will be far less important than radiative forcing from greenhouse gases.
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What about the future?
Due to the enormous complexity of the atmosphere, the most useful tools for gauging future changes are 'climate models'. These are computer-based mathematical models which simulate, in three dimensions, the climate's behavior, its components and their interactions. Climate models are constantly improving based on both our understanding and the increase in computer power, though by definition, a computer model is a simplification and simulation of reality, meaning that it is an approximation of the climate system. The first step in any modeled projection of climate change is to first simulate the present climate and compare it to observations. If the model is considered to do a good job at representing modern climate, then certain parameters can be changed, such as the concentration of greenhouse gases, which helps us understand how the climate would change in response. Projections of future climate change therefore depend on how well the computer climate model simulates the climate and on our understanding of how forcing functions will change in the future.
The IPCC Special Report on Emission Scenarios determines the range of future possible greenhouse gas concentrations (and other forcings) based on considerations such as population growth, economic growth, energy efficiency and a host of other factors. This leads a wide range of possible forcing scenarios, and consequently a wide range of possible future climates.
According to the range of possible forcing scenarios, and taking into account uncertainty in climate model performance, the IPCC projects a global temperature increase of anywhere from 1.4 - 5.8°C from 1990-2100. However, this global average will integrate widely varying regional responses, such as the likelihood that land areas will warm much faster than ocean temperatures, particularly those land areas in northern high latitudes (and mostly in the cold season).
Precipitation is also expected to increase over the 21st century, particularly at northern mid-high latitudes, though the trends may be more variable in the tropics.
Snow extent and sea-ice are also projected to decrease further in the northern hemisphere, and glaciers and ice-caps are expected to continue to retreat.
Global warming is the increase in the average temperature of the Earth's near-surface air and oceans in recent decades and its projected continuation.
Global average air temperature near the Earth's surface rose 0.74 ± 0.18 °C (1.3 ± 0.32 °F) during the past century. The Intergovernmental Panel on Climate Change (IPCC) concludes, "most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations,"[1] which leads to warming of the surface and lower atmosphere by increasing the greenhouse effect. Natural phenomena such as solar variation combined with volcanoes have probably had a small warming effect from pre-industrial times to 1950, but a small cooling effect since 1950.[2][3] These basic conclusions have been endorsed by at least 30 scientific societies and academies of science, including all of the national academies of science of the major industrialized countries. The American Association of Petroleum Geologists is the only scientific society that rejects these conclusions,[4][5] and a few individual scientists also disagree with parts of them.[6]
Climate models referenced by the IPCC project that global surface temperatures are likely to increase by 1.1 to 6.4 °C (2.0 to 11.5 °F) between 1990 and 2100.[1] The range of values reflects the use of differing scenarios of future greenhouse gas emissions and results of models with differences in climate sensitivity. Although most studies focus on the period up to 2100, warming and sea level rise are expected to continue for more than a millennium even if greenhouse gas levels are stabilized.[1] This reflects the large heat capacity of the oceans.
An increase in global temperatures can in turn cause other changes, including sea level rise, and changes in the amount and pattern of precipitation. There may also be changes in the frequency and intensity of extreme weather events, though it is difficult to connect specific events to global warming. Other effects may include changes in agricultural yields, glacier retreat, reduced summer streamflows, species extinctions and increases in the ranges of disease vectors.
Remaining scientific uncertainties include the exact degree of climate change expected in the future, and how changes will vary from region to region around the globe. There is ongoing political and public debate regarding what, if any, action should be taken to reduce or reverse future warming or to adapt to its expected consequences. Most national governments have signed and ratified the Kyoto Protocol aimed at combating greenhouse gas emissions.
REDUCE YOUR IMPACT AT HOME
Most emissions from homes are from the fossil fuels burned to generate electricity and heat. By using energy more efficiently at home, you can reduce your emissions and lower your energy bills by more than 30%.
In addition, since agriculture is responsible for about a fifth of the world’s greenhouse gas emissions, you can reduce your emissions simply by watching what you eat.
Here’s how:
Replace a regular incandescent light bulb with a compact fluorescent light bulb (cfl)
CFLs use 60% less energy than a regular bulb. This simple switch will save about 300 pounds of carbon dioxide a year. If every family in the U.S. made the switch, we’d reduce carbon dioxide by more than 90 billion pounds! You can purchase CFLs online from the Energy Federation.
Move your thermostat down 2° in winter and up 2° in summer
Almost half of the energy we use in our homes goes to heating and cooling. You could save about 2,000 pounds of carbon dioxide a year with this simple adjustment. The American Council for an Energy Efficient Economy has more tips for saving energy on heating and cooling.
Clean or replace filters on your furnace and air conditioner
Cleaning a dirty air filter can save 350 pounds of carbon dioxide a year.
Install a programmable thermostat
Programmable thermostats will automatically lower the heat or air conditioning at night and raise them again in the morning. They can save you $100 a year on your energy bill.
Choose energy efficient appliances when making new purchases
Look for the Energy Star label on new appliances to choose the most efficient models. If each household in the U.S. replaced its existing appliances with the most efficient models available, we’d eliminate 175 million tons of carbon dioxide emissions every year!
Wrap your water heater in an insulation blanket
You’ll save 1,000 pounds of carbon dioxide a year with this simple action. You can save another 550 pounds per year by setting the thermostat no higher than 120 degrees Fahrenheit.
Use less hot water
It takes a lot of energy to heat water. You can use less hot water by installing a low flow showerhead (350 pounds of carbon dioxide saved per year) and washing your clothes in cold or warm water (500 pounds saved per year) instead of hot.
Use a clothesline instead of a dryer whenever possible
You can save 700 pounds of carbon dioxide when you air dry your clothes for 6 months out of the year.
Turn off electronic devices you’re not using
Simply turning off your television, DVD player, stereo, and computer when you’re not using them will save you thousands of pounds of carbon dioxide a year.
Unplug electronics from the wall when you’re not using them
Even when turned off, things like hairdryers, cell phone chargers and televisions use energy. In fact, the energy used to keep display clocks lit and memory chips working accounts for 5 percent of total domestic energy consumption and spews 18 million tons of carbon into the atmosphere every year!
Only run your dishwasher when there’s a full load and use the energy-saving setting
You can save 100 pounds of carbon dioxide per year.
Insulate and weatherize your home
Properly insulating your walls and ceilings can save 25% of your home heating bill and 2,000 pounds of carbon dioxide a year. Caulking and weather-stripping can save another 1,700 pounds per year. The Consumer Federation of America has more information on how to better insulate your home.
Be sure you’re recycling at home
You can save 2,400 pounds of carbon dioxide a year by recycling half of the waste your household generates. Earth 911 can help you find recycling resources in your area.
Buy recycled paper products
It takes less 70 to 90% less energy to make recycled paper and it prevents the loss of forests worldwide.
Plant a tree
A single tree will absorb one ton of carbon dioxide over its lifetime. Shade provided by trees can also reduce your air conditioning bill by 10 to 15%. The Arbor Day Foundation has information on planting and provides trees you can plant with membership.
Get a home energy audit
Many utilities offer free home energy audits to find where your home is poorly insulated or energy inefficient. You can save up to 30% off your energy bill and 1,000 pounds of carbon dioxide a year. Energy Star can help you find an energy specialist.
Switch to green power
In many areas, you can switch to energy generated by clean, renewable sources such as wind and solar. The Green Power Network is a good place to start to figure out what’s available in your area.
Buy locally grown and produced foods
The average meal in the United States travels 1,200 miles from the farm to your plate. Buying locally will save fuel and keep money in your community.
Buy fresh foods instead of frozen
Frozen food uses 10 times more energy to produce.
Seek out and support local farmers markets
They reduce the amount of energy required to grow and transport the food to you by one fifth. You can find a farmer’s market in your area at the USDA website.
Buy organic foods as much as possible
Organic soils capture and store carbon dioxide at much higher levels than soils from conventional farms. If we grew all of our corn and soybeans organically, we’d remove 580 billion pounds of carbon dioxide from the atmosphere!
Avoid heavily packaged products
You can save 1,200 pounds of carbon dioxide if you cut down your garbage by 10%.
Eat less meat
Methane is the second most significant greenhouse gas and cows are one of the greatest methane emitters. Their grassy diet and multiple stomachs cause them to produce methane, which they exhale with every breath.
REDUCE YOUR IMPACT WHILE ON THE MOVE
Almost one third of the carbon dioxide produced in the United States comes from our cars, trucks and airplanes. Here are some simple, practical things you can do to reduce the amount of carbon dioxide you produce while on the move.
Reduce the number of miles you drive by walking, biking, carpooling or taking mass transit wherever possible
Avoiding just 10 miles of driving every week would eliminate about 500 pounds of carbon dioxide emissions a year! Click here to find transit options in your area.
Start a carpool with your coworkers or classmates
Sharing a ride with someone just 2 days a week will reduce your carbon dioxide emissions by 1,590 pounds a year. eRideShare.com runs a free national service connecting commuters and travelers.
Keep your car tuned up
Regular maintenance helps improve fuel efficiency and reduces emissions. When just 1% of car owners properly maintain their cars, nearly a billion pounds of carbon dioxide are kept out of the atmosphere.
Check your tires weekly to make sure they’re properly inflated
Proper inflation can improve gas mileage by more than 3%. Since every gallon of gasoline saved keeps 20 pounds of carbon dioxide out of the atmosphere, every increase in fuel efficiency makes a difference!
When it is time for a new car, choose a more fuel efficient vehicle
You can save 3,000 pounds of carbon dioxide every year if your new car gets only 3 miles per gallon more than your current one. You can get up to 60 miles per gallon with a hybrid! You can find information on fuel efficiency here and here.
Try car sharing
Need a car but don’t want to buy one? Community car sharing organizations provide access to a car and your membership fee covers gas, maintenance and insurance. Many companies – such as Flexcar -- offer low emission or hybrid cars too! Also, see ZipCar.
Try telecommuting from home
Telecommuting can help you drastically reduce the number of miles you drive every week. For more information, check out the Telework Coalition.
Fly less
Air travel produces large amounts of emissions so reducing how much you fly by even one or two trips a year can reduce your emissions significantly. You can also offset your air travel by investing in renewable energy projects.
HELP BRING ABOUT CHANGE LOCALLY, NATIONALLY AND INTERNATIONALLY
Your actions to reduce global warming can extend beyond how you personally reduce your own emissions. We all have influence on our schools, workplaces, businesses, and on society through how we make purchases, invest, take action, and vote. Here are some ways you can have a positive effect on global warming.
Encourage your school or business to reduce emissions
You can extend your positive influence on global warming well beyond your home by actively encouraging other to take action. Download our toolkits for schools and businesses to take action outside of your home.
Join the virtual march
The Stop Global Warming Virtual March is a non-political effort to bring all Americans concerned about global warming together in one place. Add your voice to the hundreds of thousands of other Americans urging action on this issue.
Encourage the switch to renewable energy
Successfully combating global warming requires a national transition to renewable energy sources such as solar, wind and biomass. These technologies are ready to be deployed more widely but there are regulatory barriers impeding them. Take action to break down those barriers with Vote Solar.
Protect and conserve forest worldwide
Forests play a critial role in global warming: they store carbon. When forests are burned or cut down, their stored carbon is release into the atmosphere -- deforestation now accounts for about 20% of carbon dioxide emissions each year. Conservation International has more information on forests and global warming.
HELP BRING ABOUT CHANGE LOCALLY, NATIONALLY AND INTERNATIONALLY
Consider the impact of your investments
If you invest your money, you should consider the impact that your investments and savings will have on global warming. You can learn more about how to ensure your money is being invested in companies, products and projects that address issues related to climate change here and here.
Make your city cool
Cities and states around the country have taken action to stop global warming by passing innovative transportation and energy saving legislation. 194 cities nationwide representing over 40 million people have made this pledge as part of the U.S. Mayors Climate Protection Agreement. Find out how to make your city a cool city.
Tell Congress to act
The McCain Lieberman Climate Stewardship and Innovation Act would set a firm limit on carbon dioxide emissions and then use free market incentives to lower costs, promote efficiency and spur innovation. Tell your representative to support it.
Make sure your voice is heard!
We must have a stronger commitment from our government in order to stop global warming and implement solutions and such a commitment won’t come without a dramatic increase in citizen lobbying for new laws with teeth. Get the facts about U.S. politicians and candidates at Project Vote Smart and The League of Conservation Voters. Make sure your voice is heard by voting!
Carbon Dioxide from Power Plants
In 2002 about 40% of U.S. carbon dioxide emissions stem from the burning of fossil fuels for the purpose of electricity generation. Coal accounts for 93 percent of the emissions from the electric utility industry. US Emissions Inventory 2004 Executive Summary p. 10
Coal emits around 1.7 times as much carbon per unit of energy when burned as does natural gas and 1.25 times as much as oil. Natural gas gives off 50% of the carbon dioxide, the principal greenhouse gas, released by coal and 25% less carbon dioxide than oil, for the same amount of energy produced. Coal contains about 80 percent more carbon per unit of energy than gas does, and oil contains about 40 percent more. For the typical U.S. household, a metric ton of carbon equals about 10,000 miles of driving at 25 miles per gallon of gasoline or about one year of home heating using a natural gas-fired furnace or about four months of electricity from coal-fired generation.
Carbon Dioxide Emitted from Cars
About 20% of U.S carbon dioxide emissions comes from the burning of gasoline in internal-combustion engines of cars and light trucks (minivans, sport utility vehicles, pick-up trucks, and jeeps).US Emissions Inventory 2004 Vehicles with poor gas mileage contribute the most to global warming. For example, according to the E.P.A's 2000 Fuel Economy Guide, a new Dodge Durango sports utility vehicle (with a 5.9 liter engine) that gets 12 miles per gallon in the city will emit an estimated 800 pounds of carbon dioxide over a distance of 500 city miles. In other words for each gallon of gas a vehicle consumes, 19.6 pounds of carbon dioxide are emitted into the air. [21] A new Honda Insight that gets 61 miles to the gallon will only emit about 161 pounds of carbon dioxide over the same distance of 500 city miles. Sports utility vehicles were built for rough terrain, off road driving in mountains and deserts. When they are used for city driving, they are so much overkill to the environment. If one has to have a large vehicle for their family, station wagons are an intelligent choice for city driving, especially since their price is about half that of a sports utility. Inasmuch as SUV's have a narrow wheel base in respect to their higher silhouette, they are four times as likely as cars to rollover in an accident. [33]
The United States is the largest consumer of oil, using 20.4 million barrels per day. In his debate with former Defense Secretary Dick Cheney, during the 2000 Presidential campaign, Senator Joseph Lieberman said, "If we can get 3 miles more per gallon from our cars, we'll save 1 million barrels of oil a day, which is exactly what the (Arctic National Wildlife) Refuge at its best in Alaska would produce."
If car manufacturers were to increase their fleets' average gas mileage about 3 miles per gallon, this country could save a million barrels of oil every day, while US drivers would save $25 billion in fuel costs annually.
Carbon Dioxide from Trucks
About another 13% of U.S carbon dioxide emissions comes from trucks used mostly for commercial purposes.[20]
Carbon Dioxide from Airplanes
The UN's Intergovernmental Panel on Climate Change estimates that aviation causes 3.5 percent of global warming, and that the figure could rise to 15 percent by 2050.
Carbon Dioxide from Buildings
Buildings structure account for about 12% of carbon dioxide emissions.
Methane
While carbon dioxide is the principal greenhouse gas, methane is second most important. According to the IPCC, Methane is more than 20 times as
effective as CO2 at trapping heat in the atmosphere. US Emissions Inventory 2004 Levels of atmospheric methane have risen 145% in the last 100 years. [18] Methane is derived from sources such as rice paddies, bovine flatulence, bacteria in bogs and fossil fuel production. Most of the world’s rice, and all of the rice in the United States, is grown on flooded fields. When fields are flooded, anaerobic conditions develop and the organic matter in the soil decomposes, releasing CH4 to the atmosphere, primarily through the rice plants. US Emissions Inventory 2004
Nitrous oxide
Another greenhouse gas is Nitrous oxide (N2O), a colourless, non-flammable gas with a sweetish odour, commonly known as "laughing gas", and sometimes used as an anaesthetic. Nitrous oxide is naturally produced by oceans and rainforests. Man-made sources of nitrous oxide include nylon and nitric acid production, the use of fertilisers in agriculture, cars with catalytic converters and the burning of organic matter. Nitrous oxide is broken down in the atmosphere by chemical reactions that involve sunlight.
Deforestation
After carbon emissions caused by humans, deforestation is the second principle cause of atmospheric carbn dioxide. (NASA Web Site) Deforestation is responsible for 25% of all carbon emissions entering the atmosphere, by the burning and cutting of about 34 million acres of trees each year. We are losing millions of acres of rainforests each year, the equivalent in area to the size of Italy. [22] The destroying of tropical forests alone is throwing hundreds of millions of tons of carbon dioxide into the atmosphere each year. We are also losing temperate forests. The temperate forests of the world account for an absorption rate of 2 billion tons of carbon annually. [3] In the temperate forests of Siberia alone, the earth is losing 10 million acres per year.
City Gridlock
Cities are tolerating gridlock. In 1996 according to an annual study by traffic engineers [as reported in the San Francisco Chronicle December 10, 1996] from Texas A and M University, it was found that drivers in Los Angeles and New York City alone wasted 600 million gallons of gas annually while just sitting in traffic. The 600 million gallons of gas translates to about 7.5 million tons of carbon dioxide in just those two cities.
Carbon in Atmosphere and Ocean
The atmosphere contains about 750 billion tons of carbon, while 800 billion tons are dissolved in the surface layers of
the world's oceans.
STOP GLOBAL WARMING
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Use Compact Fluorescent Bulbs
Replace 3 frequently used light bulbs with compact fluorescent bulbs. Save 300 lbs. of carbon dioxide and $60 per year.
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Inflate Your Tires
Keep the tires on your car adequately inflated. Check them monthly. Save 250 lbs. of carbon dioxide and $840 per year.
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Change Your Air Filter
Check your car's air filter monthly. Save 800 lbs. of carbon dioxide and $130 per year.
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Fill the Dishwasher
Run your dishwasher only with a full load. Save 100 lbs. of carbon dioxide and $40 per year.
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Use Recycled Paper
Make sure your printer paper is 100% post consumer recycled paper. Save 5 lbs. of carbon dioxide per ream of paper.
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Adjust Your Thermostat
Move your heater thermostat down two degrees in winter and up two degrees in the summer. Save 2000 lbs of carbon dioxide and $98 per year.
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Check Your Waterheater
Keep your water heater thermostat no higher than 120°F. Save 550 lbs. of carbon dioxide and $30 per year.
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Change the AC Filter
Clean or replace dirty air conditioner filters as recommended. Save 350 lbs. of carbon dioxide and $150 per year.
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Take Shorter Showers
Showers account for 2/3 of all water heating costs. Save 350 lbs. of carbon dioxide and $99 per year.
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Install a Low-Flow Showerhead
Using less water in the shower means less energy to heat the water. Save 350 lbs. of carbon dioxide and $150.
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Buy Products Locally
Buy locally and reduce the amount of energy required to drive your products to your store.
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Buy Energy Certificates
Help spur the renewable energy market and cut global warming pollution by buying wind certificates and green tags.
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Buy Minimally Packaged Goods
Less packaging could reduce your garbage by about 10%. Save 1,200 pounds of carbon dioxide and $1,000 per year.
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Buy a Hybrid Car
The average driver could save 16,000 lbs. of CO2 and $3,750 per year driving a hybrid
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Buy a Fuel Efficient Car
Getting a few extra miles per gallon makes a big difference. Save thousands of lbs. of CO2 and a lot of money per year.
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Carpool When You Can
Own a big vehicle? Carpooling with friends and co-workers saves fuel. Save 790 lbs. of carbon dioxide and hundreds of dollars per year.
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Reduce Garbage
Buy products with less packaging and recycle paper, plastic and glass. Save 1,000 lbs. of carbon dioxide per year.
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Plant a Tree
Trees suck up carbon dioxide and make clean air for us to breath. Save 2,000 lbs. of carbon dioxide per year.
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Insulate Your Water Heater
Keep your water heater insulated could save 1,000 lbs. of carbon dioxide and $40 per year.
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Replace Old Appliances
Inefficient appliances waste energy. Save hundreds of lbs. of carbon dioxide and hundreds of dollars per year.
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Weatherize Your Home
Caulk and weather strip your doorways and windows. Save 1,700 lbs. of carbon dioxide and $274 per year.
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Use a Push Mower
Use your muscles instead of fossil fuels and get some exercise. Save 80 lbs of carbon dioxide and x $ per year.
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Unplug Un-Used Electronics
Even when electronic devices are turned off, they use energy. Save over 1,000 lbs of carbon dioxide and $256 per year.
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Put on a Sweater
Instead of turning up the heat in your home, wear more clothes Save 1,000 lbs. of carbon dioxide and $250 per year.
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Insulate Your Home
Make sure your walls and ceilings are insulated. Save 2,000 lbs. of carbon dioxide and $245 per year.
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Air Dry Your Clothes
Line-dry your clothes in the spring and summer instead of using the dryer. Save 700 lbs. of carbon dioxide and $75 per year.
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Switch to a Tankless Water Heater
Your water will be heated as you use it rather than keeping a tank of hot water. Save 300 lbs. of carbon dioxide and $390 per year.
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Switch to Double Pane Windows
Double pane windows keep more heat inside your home so you use less energy. Save 10,000 lbs. of carbon dioxide and $436 per year.
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Buy Organic Food
The chemicals used in modern agriculture pollute the water supply, and require energy to produce.
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Bring Cloth Bags to the Market
Using your own cloth bag instead of plastic or paper bags reduces waste and requires no additional energy.
http://www.stopglobalwarming.org/sgw_actionitems.asp
Efficient Appliances Save Energy -- and Money
Consumers get lower utility bills, and we all get a cleaner environment.
The major appliances in your home -- refrigerators, clothes washers, dishwashers -- account for a big chunk of your monthly utility bill. And if your refrigerator or washing machine is more than a decade old, you're spending a lot more on energy than you need to.
Today's major appliances don't hog energy the way older models do because they must meet minimum federal energy efficiency standards. These standards have been tightened over the years, so any new appliance you buy today has to use less energy than the model you're replacing. For instance, if you buy one of today's most energy-efficient refrigerators, it will use less than half the energy of a model that's 12 years old or older.
Of course, efficient appliances don't just save you money; they're good for the environment. The less energy we all use, the lower our demand on power plants, which means less pollution. The trick is to figure out which models use the least energy. Here are some guidelines.
Look for the Energy Star® label. Energy Star models are the most energy efficient in any product category, exceeding the energy efficiency minimums set by the federal government. If you remember only one rule when you shop, remember to look for the Energy Star label. In some parts of the country, utilities and state governments even sweeten the deal by offering rebates on Energy Star-rated models. Check http://www.energystar.gov for details.
Use the EnergyGuide label. Some uninformed salespeople might tell you that a model you're looking at is the most efficient because it has an EnergyGuide label. Not exactly. All new appliances must carry the EnergyGuide label, either on the appliance itself or on the packaging. The label allows you to compare the typical annual energy consumption and operating cost of different models of any type of appliance you're thinking of buying.
Get the right size. Make sure the product you're buying suits your needs. Oversized air conditioners, water heaters and refrigerators waste energy and money; in many cases they also don't perform as well.
Whenever possible choose appliances that run on natural gas rather than electricity. Usually it's more efficient to burn natural gas where it's needed -- in your home -- than to burn it at a power plant, convert the heat to electricity and then send the electricity over wires to your house. Look for dryers, stoves and water heaters that run on natural gas.
Think long term. Many of the most energy-efficient appliances cost more initially, but they'll save you money in the long run. Expect to keep most major appliances between 10 and 20 years. A more efficient appliance soon pays for itself; lower monthly utility bills over the lifetime of the appliance will more than offset a higher purchase price. In addition, the latest resource-efficient clothes washers and dishwashers not only save electricity, they also use a lot less water and can reduce your water bill.
Below is more specific information to keep in mind if you're in the market for any of the following major appliances.
NRDC: Setting the Standard
Energy efficiency standards may not be as high profile as saving endangered species or cleaning up toxic waste, but they are a hugely important cause for environmentalists. Since their inception, these standards have saved consumers over $200 billion -- about $2,000 per household -- while cutting electricity use 5 percent and reducing levels of pollution that come from the power plants that produce the electricity by over 2 percent. These savings are projected to more than double over the next 20 years even without new action. If NRDC's recommendations for new and updated standards are adopted, these savings will more than triple.
NRDC's energy program has played an important role in creating the framework under which continued improvements in appliance energy efficiency have occurred. NRDC led the negotiations that crafted the National Appliance Energy Conservation Act (1987), the law that impelled manufacturers to develop today's energy-efficient appliances.
In the early 1990s, David Goldstein, co-director of NRDC's energy program, proposed the Super Efficiency Refrigerator Program, which spurred development of the new refrigerator technology from which consumers are benefiting today. Similar programs are offered by the Consortium for Energy Efficiency. David was awarded a 2002 MacArthur Fellowship for his innovative work proving that energy efficiency makes good economic sense.
REFRIGERATORS
If you are thinking of replacing an old appliance, the refrigerator is a good place to start. New refrigerators consume 75 percent less energy than those produced in the late 1970s. A family replacing a 1980 vintage fridge with one that meets today's standards will save more than $100 a year in utility costs. Go one step further and buy an Energy Star-qualified model, and your new refrigerator will save you an additional 15 percent or more by employing better insulation, more efficient compressors and more precise temperature control and defrost mechanisms.
Energy-Saving Purchasing Tips:
• Refrigerators with freezers on top use 10 to 15 percent less energy than a side-by-side model of equivalent size.
• Generally, the larger the refrigerator, the greater the energy consumption. But one large refrigerator will use less energy than two smaller ones with the same total volume or a smaller fridge plus a separate freezer.
CLOTHES WASHERS
The energy efficiency of standard top-loading washers has doubled over the last two decades, mostly by decreasing the amount of water used. (Most of a washer's energy consumption goes to heating water.) Front-loading washers have also become more readily available. They generally use less water than top-loaders because they don't have to totally submerge clothes. Their tumbling action constantly lifts water and drops it back down onto clothing. Energy Star top-loaders, however, can be just as efficient as front loaders. Look for the EnergyGuide or Energy Star labels to compare efficiencies.
Replacing a pre-1994 washer with an Energy Star model can save a family $110 a year on utility bills. Energy Star washers use 50 percent less energy than other standard models, and only 18 to 25 gallons of water for a full-sized load, compared to 40 gallons for standard full-size washers. Many Energy Star models also advertise lower fabric wear, better stain removal and briefer drying times.
Energy-Saving Purchasing Tips:
• Choose the right size washer. A smaller washer may be more efficient for small households. But if you have a large family and have to do multiple loads in a washer that's too small for your needs, you could lose any possible energy savings.
• Look for a washer with adjustable water levels. This gives you the option of using less water to wash small loads.
• Choose a washer with a faster spin speed. This allows more water to be removed after the wash, reducing the drying time and your dryer's energy use.
• Use a gas dryer rather than an electric dryer where possible.
DISHWASHERS
A new dishwasher is not only more efficient than older models, but it's also better at getting dishes clean. Manufacturers no longer recommend that you pre-wash your dishes. Simply scrape the remaining food off your plates and place them in the machine as is. This will save you time and save money on your water bill.
The most efficient dishwashers use less hot water, have energy-efficient motors and use sensors to determine the length of the wash cycle and the water temperature needed to do the job. The newest Energy Star dishwashers are 25 percent more efficient than the minimum federal standards. Replacing a pre-1994 dishwasher with an Energy Star model can save $25 a year on utility costs.
Energy-Saving Purchasing Tips:
• Choose a dishwasher with a "light wash" or "energy-saving" wash cycle. It uses less water and operates for a shorter period of time for dishes that are just slightly soiled.
• Look for dishwashers that have an energy-saving cycle that allows dishes to be air-dried with circulation fans, rather than heat-dried with energy-wasting heating coils.
ROOM AIR CONDITIONERS
The most efficient room air conditioners have higher-efficiency compressors, fan motors and heat-transfer surfaces than previous models. A high-efficiency unit reduces energy consumption by 20 to 50 percent. Replacing a 10-year-old model with an Energy Star model can cut energy bills by an average of $14 a year.
Energy-Saving Purchasing Tips:
• Remember, the biggest unit isn't always the best choice, especially for small areas. A smaller unit running for a long period of time operates more efficiently and is more effective at decreasing humidity than a larger unit that goes on and off frequently.
• If you're comparing several similar units, choose the one with the highest Energy Efficiency Ratio. You can find the EER on the unit or its packaging. The minimum EER required by federal law is 9.7; the most efficient air conditioners of 2003 have an EER of 11.7.
CENTRAL AIR CONDITIONERS
If your central air conditioning system is more than 10 years old, replacing it with an Energy Star model could reduce your energy consumption for cooling by 20 percent.
Energy-Saving Purchasing Tips:
• Look for the seasonal energy efficiency ratio (SEER). Old units typically have a SEER of 6 or 7. In 2006, new standards go into effect, raising the minimum SEER for central air conditioners to 13. Energy Star models already meet the SEER 13 standard, and also perform more efficiently when it's hot.
• For maximum efficiency on the hottest days, the air conditioner should have a thermal expansion valve (TVX), and the high temperature rating (EER) on your unit should be at least 11.6.
• For optimal performance, buy a matched system of indoor unit, condenser and even thermostat.
• Get a reliable contractor to make sure your new unit is the right size for your home, and have it professionally installed. Even the most efficient system can't make up for the energy loss due to improper sizing and poor installation.
• Have your contractor make sure all your ducts are sealed and insulated. Duct tests require a fan and a pressure gauge -- they cannot be done by sight.
WATER HEATERS
Water heating is typically the third largest energy expense in your home, accounting for about 14 percent of your energy bill. An old water heater can operate for years at very low efficiency before it finally fails. If your gas water heater is more than 10 years old, it probably operates at less than 50 percent efficiency.
Energy-Saving Purchasing Tips:
• Calculate how much hot water your household uses at peak times. Figure that a clothes washer on hot wash/hot rinse can use about 32 gallons of hot water; a shower, 20 gallons. Washing dishes by hand can use 10 to 15 gallons, and automatic dishwashers, about 8 gallons.
• Match this figure with the "first hour rating" (FHR) on the EnergyGuide label. The FHR measures how many gallons of hot water your heater can deliver during a busy hour. Don't be misled by the size of the tank -- it doesn't necessarily correlate with FHR.
• Once you've found the right FHR range for your household, check the unit's Energy Factor (EF), which rates efficiency. A high-efficiency gas model would have an EF around 0.8.
• A natural gas unit will cost less to operate than electric.
HOME ELECTRONICS
For most products, the Energy Star label is your assurance that the product will operate more efficiently than a standard model. But Energy Star TVs, audio equipment, telephones, computers and printers earn the label primarily because they draw only a small amount of power when not in use -- regardless of the amount of power they consume when operating. When buying electronics, do look for the Energy Star label, but also keep a few general caveats in mind.
Energy-Saving Purchasing Tips:
• Ink jet printers tend to be more energy-efficient than lasers.
• LCD televisions and monitors draw less power than CRT or plasma screens.
• Small lightweight power supplies tend to be more energy efficient than large, heavy transformer-based power supplies.
MORE SMART SHOPPING TIPS
• Check for incentives. Some states offer rewards for buying the most energy-efficient appliances. Connecticut and California, for example, have rebate programs that will refund part of the purchase price of certain new energy-efficient appliances. Maryland eliminates sales tax on some appliances with the Energy Star label. Check with your local utility and the Energy Star Rebate Locator to find out if cash rebates or other incentives are available in your area, or see our state-by-state listing.
• Use the Internet. Several websites contain additional useful information. The EPA's Energy Star website has information on appliance models that carry the Energy Star label and where you can buy them. The American Council for an Energy Efficient Economy publishes a yearly list of the most energy-efficient appliances. And the Consortium for Energy Efficiency has information on programs promoting energy efficiency in the home.
EASY ENERGY-SAVING HABITS (Free!)
Don't forget the basics. This simple stuff will save energy -- and money -- right now.
1. Unplug
o Unplug seldom-used appliances, like an extra refrigerator in the basement or garage that contains just a few items. You may save around $10 every month on your utility bill.
o Unplug your chargers when you're not charging. Every house is full of little plastic power supplies to charge cell phones, PDA's, digital cameras, cordless tools and other personal gadgets. Keep them unplugged until you need them.
o Use power strips to switch off televisions, home theater equipment, and stereos when you're not using them. Even when you think these products are off, together, their "standby" consumption can be equivalent to that of a 75 or 100 watt light bulb running continuously.
2. Set Computers to Sleep and Hibernate
o Enable the "sleep mode" feature on your computer, allowing it to use less power during periods of inactivity. In Windows, the power management settings are found on your control panel. Mac users, look for energy saving settings under system preferences in the apple menu.
o Configure your computer to "hibernate" automatically after 30 minutes or so of inactivity. The "hibernate mode" turns the computer off in a way that doesn't require you to reload everything when you switch it back on. Allowing your computer to hibernate saves energy and is more time-efficient than shutting down and restarting your computer from scratch.
3. Take Control of Temperature
o Set your thermostat in winter to 68 degrees or less during the daytime, and 55 degrees before going to sleep (or when you're away for the day). During the summer, set thermostats to 78 degrees or more. (Click here for a more detailed summer energy-saving tip.)
o Use sunlight wisely. During the heating season, leave shades and blinds open on sunny days, but close them at night to reduce the amount of heat lost through windows. Close shades and blinds during the summer or when the air conditioner is in use or will be in use later in the day.
o Set the thermostat on your water heater between 120 and 130 degrees. Lower temperatures can save more energy, but you might run out of hot water or end up using extra electricity to boost the hot water temperature in your dishwasher.
4. Use Appliances Efficiently
o Set your refrigerator temperature at 38 to 42 degrees Fahrenheit; your freezer should be set between 0 and 5 degrees Fahrenheit. Use the power-save switch if your fridge has one, and make sure the door seals tightly. You can check this by making sure that a dollar bill closed in between the door gaskets is difficult to pull out. If it slides easily between the gaskets, replace them.
o Don't preheat or "peek" inside the oven more than necessary. Check the seal on the oven door, and use a microwave oven for cooking or reheating small items.
o Wash only full loads in your dishwasher, using short cycles for all but the dirtiest dishes. This saves water and the energy used to pump and heat it. Air-drying, if you have the time, can also reduce energy use.
o In your clothes washer, set the appropriate water level for the size of the load; wash in cold water when practical, and always rinse in cold.
o Clean the lint filter in the dryer after each use. Dry heavy and light fabrics separately and don't add wet items to a load that's already partly dry. If available, use the moisture sensor setting. (A clothesline is the most energy-efficient clothes dryer of all!)
5. Turn Out the Lights
o Don't forget to flick the switch when you leave a room.
o Remember this at the office, too. Turn out or dim the lights in unused conference rooms, and when you step out for lunch. Work by daylight when possible. A typical commercial building uses more energy for lighting than anything else.
http://www.nrdc.org/air/energy/genergy/simple.asp
http://www.nrdc.org/air/energy/genergy/longterm.asp