Introduction

Mean surface temperature change for the period 1999 to 2008 relative to the average temperatures from 1940 to 1980A phenomenon (otherwise known as climate change or the greenhouse effect) whereby solar radiation that has reflected back off the surface of the earth remains trapped at atmospheric levels, due to the build-up of CO2 and other greenhouse gases, rather than being emitted back into space. The effect of this is a warming of the global atmosphere.

The term global warming is often used synonymously with the term climate change, but the two terms have distinct meanings. Global warming is the combined result of anthropogenic (human-caused) emissions of greenhouse gases and changes in solar irradiance, while climate change refers to any change in the state of the climate that can be identified by changes in the average and/or the variability of its properties (e.g., temperature, precipitation), and that persists for an extended period, typically decades or longer.Climate change is a long-standing phenomenon, as the mix of the various gases that make up the earth's atmosphere have changed over long periods of time, so average global temperatures have fluctuated. What is alleged to be different about the current spell of global warming is that it is taken to be (1) caused by human action and (2) occurring at an unprecedented rate. The consequences of global warming remain uncertain, but climate change models predict deforestation, desertification, a poleward shift of vegetation and animal populations, rising sea levels, and decreased precipitation.

CAUSES OF GLOBAL WARMING The Green house gases are the main culprits of the global warming. The green house gases like carbon dioxide, methane, and nitrous oxide are playing hazards in the present times. These green house gases trap heat in earths atmosphere and thus result in increasing the temperature of earth. The excessive emission of these gases is the major cause of global warming.

The Greenhouse Effect Seen from space, our atmosphere is but a tiny layer of gas around a huge bulky planet. But it is this gaseous outer ring and its misleadingly called greenhouse effect that makes life on Earth possible and that could destroy life as we know it.

Greenhouse effect schematic showing energy flows between space, the atmosphere, and earth's surface. Energy exchanges are expressed in watts per square meter (W/m2).The sun is the Earths primary energy source, a burning star so hot that we can feel its heat from over 150 million kilometers away. Its rays enter our atmosphere and shower upon on our planet. About one third of this solar energy is reflected back into the universe by shimmering glaciers, water and other bright surfaces. Two thirds, however, are absorbed by the Earth, thus warming land, oceans, and atmosphere.Much of this heat radiates back out into space,but some of it is stored in the atmosphere. Thisprocess iscalled the greenhouse effect. Without it, the Earths average temperature would be a chilling -18 degrees Celsius, even despite the suns constant energy supply. In a world like this, life on Earth would probably have never emerged from the sea. Thanks to the greenhouse effect, however, heat emitted from the Earth is trapped in the atmosphere, providing us with a comfortable average temperature of 14 degrees.So, how does it work? Sunrays enter the glass roof and walls of a greenhouse. But once they heat up the ground, which, in turn, heats up the air inside the greenhouse, the glass panels trap that warm air and temperatures increase. Our planet, however, has no glass walls; the only thing that comes close to acting as such is our atmosphere. But in here, processes are way more complicated than in a real greenhouse. Like a radiator in space Only about half of all solar energy that reaches the Earth is infrared radiation and causes immediate warming when passing the atmosphere. The other half is of a higher frequency, and only translates into heat once it hits Earth and is later reflected back into space as waves of infrared radiation.This transformation of solar radiation in to infrared radiation is crucial, because infrared radiation can be absorbed by the atmosphere. So, on a cold and clear night for example, parts of this infrared radiation that would normally dissipate into space get caught up in the Earths atmosphere. And like a radiator in the middle of a room, our atmosphere radiates this heat into all directions.Parts of this heat are finally sent out in the frozen nothingness of space, parts of it are sent back to Earth where they step up global temperatures. Just how much warmer it gets down here depends on how much energy is absorbed up there and this, in turn, depends on the atmospheres composition.

The switch from carbon dioxide to oxygenNitrogen, oxygen, and argon make up 98 percent of the Earths atmosphere. But they do not absorb significant amounts of infrared radiation, and thus do not contribute to the greenhouse effect. It is the more exotic components like water vapour, carbon dioxide, ozone, methane, nitrous oxide, and chlorofluorocarbons that absorb heat and thus increase atmospheric temperatures. Studies indicate that until some 2.7 billion years ago, there was so much carbon dioxide (CO2) and methane in our atmosphere that average temperatures on Earth were as high as 70 degrees. But bacteria and plants slowly turned CO2 into oxygen and the concentration of CO2 in our current atmosphere dropped to just about 0.038 percent or 383 parts per million (ppm), a unit of measurement used for very low concentrations of gases that has become a kind of currency in climate change debates.

Minuscule changes global impact But while we are still far from seeing major concentrations of CO2 in our atmosphere, slight changes already alter the way our celestial heating system works. Measurements of carbon dioxide amounts from Mauna Loa Observatory in Hawaii show that CO2 has increased from about 313 ppm in 1960 to about 375 ppm in 2005. That means for every million particles in our atmosphere, there are now 62 CO2-particles more than in 1960. Even if this does not seem like much, scientists say this increase most probably caused by human activities is mainly responsible for rising global temperatures throughout the last decades.

The second major greenhouse gas after carbon dioxide, which causes global warming, is Methane. Methane's Huge ImpactPer unit of volume, it is twenty times more potent than carbon dioxide when its impact is measured over the course of a century. When you consider its effects within a single decade, methane is 100 times as powerful as carbon dioxide as a greenhouse gas!Carbon levels in the atmosphere are about 385 parts per million (ppm) currently, whereas methane is only about 1.8 ppm. But because methane is so powerful, it has the potential to have significant impacts on the future of global warming. Methane is created when bacteria break down organic matter under oxygen-starved conditions. This occurs when organic matter is trapped underwater, as in rice paddies. It also takes place in the intestines of herbivorous animals, such as cows, sheep, and goats. Because human agriculture has grown over time to engulf most of the arable land on the planet, it is now adding a lot of methane to the atmosphere. Landfills and leakage from natural gas fields (methane is a component of natural gas) are also significant sources of methane. Clathrates are a hidden source of Methane. Clathrates are frozen chunks of ice and methane that rest at the bottom of the world's oceans. As the water warms, the ice melts, and the methane is released. If the current global warming, which is caused by humans, were to cause changes in the Earth's ocean currents, then a rapid melting of clathrates would be possible. This too would create a positive feedback loop that would cause further global warming. It is believed that some of the warming cycles in the Earth's history have been caused by the sudden thawing of clathrates.A Growing ProblemThe "green revolution" of the twentieth century has allowed the farmers of the world to use chemical fertilizers and machines to produce far more food than they ever did before. One of the primary components of the green revolution has been the development of nitrogen fertilizers that dramatically accelerate the growth and productivity of plants in the field. Plants "fix," or capture, nitrogen on their own as well, but green revolution technologies have become so popular that humans are now adding more nitrogen to the earth than all of the plants in the world combined!Nitrogen oxides have 300 times more heat-trapping capacity per unit of volume than does carbon dioxide, and we release them every time we apply fertilizer to soil. A recent United Nations Food and Agriculture Organization study found that modern farming is contributing more to global warming than all of the transportation sector combined! This is due partly to the fuel burned in modern farming, but more significantly, to the release of methane and nitrogen oxides. PermafrostPermafrost is a solid structure of frozen soil, extending to depths of 2.200 feet in some areas of the arctic and subarctic regions, containing grasses, roots, sticks, much of it dating back to 30,000 years. About 25% of the land areas of the Northern Hemisphere hold permafrost, which is defined as soil whose temperature has been 32 degrees Fahrenheit (0 degrees Celsius) for a period of at least 2 years. Permafrost is under 85% of Alaska land surface and much of Canada, Scandinavia and Siberia and holds about 14 per cent of the world's carbon. The hard permafrost on which is built homes and other buildings, can, with rising temperatures, turn into a soft material causing subsidence and damage to buildings, electric generating stations, pipelines and other structures. Ground instability would cause erosion, affect terrain, slopes, roads, foundations and more.Svein Tveitdal, Managing Director of the Global Resource Information Database (GRID) in Arendal, Norway, a UNEP environmental information center monitoring the thawing of permafrost, told a meeting at the 21st session of the United Nation's Governing Council in Nairobi, Kenya on February 7, 2001: "Permafrost has acted as a carbon sink, locking away carbon and other greenhouse gases like methane, for thousands of year. But there is now evidence that this is no longer the case, and the permafrost in some areas is starting to give back its carbon. This could accelerate the greenhouse effect."

In a December, 2005 study climate models at National Center for Atmospheric Research (NCAR) show that climate change may thaw the permafrost located in the top 10 feet of permafrost, releasing carbon dioxide into the atmosphere. "People have used models to study permafrost before, but not within a fully interactive climate system model," says NCAR's David Lawrence, the lead author. The coauthor is Andrew Slater of the University of Colorado's National Snow and Ice Data Center. "Thawing permafrost could send considerable amounts of water to the oceans," says Slater, who notes that runoff to the Arctic has increased about 7 percent since the 1930s. According to the NCAR press release (December 19, 2005)permafrost may contain 30% of all the carbon found in soil worldwide. In areas to a depth of 11.2 feet climate models (assuming business as usual scenarios) show permafrost presently in an area of 4,000,000 square miles shrinking to 1,000,000 square miles by 2050 and 400,000 square miles by 2100. With a scenario of low emissions (assuming a high degree use of alternative energy sources and conservation) permafrost is still expected to shrink to 1.5 million miles by 2100.........In a USA Today (December 26, 2005) interview David Lawrence says, "If that much near-surface permafrost thaws, it could release considerable amounts of greenhouse gases into the atmosphere, and that could amplify global warming," .."We could be underestimating the rate of global temperature increase."

In a study reported in the journal Science June 16, 2006 (see San Francisco Chronicle article) researchers say that thawing permafrost may add to the buildup in atmospheric greenhouse gases significantly, stating that present climate models do not include releases of Siberian carbon dioxide from permafrost. Dr. Ted Schuur of the University of Florida traveled to Siberia and secured samples of permafrost soil up to 10 feet in length, maintaining it in a frozen state until arriving back in his laboratory, where the thawing soil was attacked by microbes, releasing carbon dioxide in the process. The frightening scenario that scientists, Sergey A. Zimov of the Russian Academy of Sciences, Ted Schuur and Stuart Chapin III of the University of Alaska, paint is one of hundreds of billions of tons of greenhouse gases entering an already destabilized atmosphere this century, spurring yet more warming in a positive feedback syndrome.Extend this scenario to Alaska, Canada and Scandinavia, where permafrost underlies much of these regions and there's no other way to describe it. We're in trouble.

TundraA name very suited to the environs of the arctic and subarctic, tundra means 'treeless plain' in Finnish. The tundra is a biome (a major segment of a particular region having distinctive vegetation, animals and microorganisms adapted to a unique climate), home to about 1700 kinds of plants, including shrubs, mosses, grasses, lichens and 400 kinds of flowers.

About 50 billion tons of carbon are estimated to be held in a frozen state in the tundra, and now the tundra is beginning to become a source of carbon dioxide. In the 1970's University of California biologist Walter Oechel studied carbon dioxide emissions in the tundra, which until this time had been thought of as a carbon sink. Doing further tests in the 1980's, Oechel discovered that this was no longer the case, that warming temperatures had changed the tundra to a net emitter of carbon dioxide. Says Oechel, " We found to our great surprise that the tundra was already losing carbon dioxide to the atmosphere. So that by the start of these experiments, which was in 1982, the tundra had already warmed and dried enough, that its historic role as a carbon sink had reversed and changed. It was now losing carbon dioxide to the atmosphere. That was totally unexpected."Man-made Causes of Global WarmingMan-made causes probably do the most damage to our planet. There are many man-made causes of global warming. Pollution is one of the biggest man-made problems. Pollution comes in many shapes and sizes. Burning fossil fuels is one thing that causes pollution. Fossil fuels are fuels made of organic matter such as coal, or oil. When fossil fuels are burned they give off a green house gas called CO2. Power plants. These power plants emit large amounts of carbon dioxide produced from burning of fossil fuels for the purpose of electricity generation. Coal is the major fuel that is burnt in these power plants. Coal produces around 1.7 times as much carbon dioxide per unit of energy when flamed as does natural gas and 1.25 times as much as oil. The coal gives out eighty percent more carbon per unit of energy it produces as compared to natural gas. Another major source of carbon dioxide in the atmosphere is the emission from the cars and other vehicles. About twenty percent of carbon dioxide emitted in the atmosphere comes from burning of gasoline in the engines of the vehicles. This is true for most of the developed countries. Moreover if sports bike and vehicles that are essentially designed for rough terrain, emit more carbon dioxide when used for general purpose on roads. It is always better to use vehicles designed for city driving on the city roads. MiningMining coal and oil allows methane to escape. How does it escape? Methane is naturally in the ground. When coal or oil is mined you have to dig up the earth a little bit. When you dig up the fossil fuels you dig up the methane as well letting it escape into the atmosphere. Cars and Airplanes

About 33% 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 2006 page 8 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. 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.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. 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.

PopulationMore people means more food, and more methods of transportation. That means more methane because there will be more burning of fossil fuels (if you're into gas burning cars like our planet is), and more agriculture. If you've been in a barn filled with animals and you smelled something terrible, you were smelling methane. Another source of methane is manure. Because more food is needed to feed the population we have to raise food. Animals like cows are a source of food which means more manure and hence more methane. Another problem with the increasing population is transportation. More people means more cars, and more cars means more pollution. Also, many people have more than one car. There are definitely ways of raising animals and farming that use no manure and no methane. Once we realized the problem we should have stopped immediately using manure. Instead we choose to continue killing the planet. We are a very stubborn race.

Since CO2 contributes to global warming, the increase in population makes the problem worse because we breathe out CO2. Also, the trees that convert our CO2 to oxygen are being cut down because we're using the land that we cut the trees down from as property for our homes and buildings. We are not replacing the trees (trees are a very important part of our eco-system), so we are constantly taking advantage of our natural resources and giving nothing back in return.Deforestation Deforestation is to be blamed for 25% of all carbon dioxide release entering the atmosphere, by the cutting and burning of about 34 million acres of trees each year. Trees collect the CO2 that we breathe out and give away from various other sources, and they give back oxygen that we breathe in. Thus, cutting of trees is leading to greater concentration of carbon dioxide in the atmosphere. Greater urbanization, requirement of land for factories and buildings, requirement of timber are all reasons that are leading to deforestation, which in turn is leading to global warming.

The Consequences of Global Warming

On Weather PatternsHigher temperatures could lead to increased droughts and wildfires, heavier rainfall and a greater number of Category 4 and 5 hurricanes.More Powerful and Dangerous HurricanesWarmer water in the oceans pumps more energy into tropical storms, making them stronger and potentially more destructive.Warning signs today: The number of category 4 and 5 storms has greatly increased over the past 35 years, along with ocean temperature. The 2005 Atlantic hurricane season was the most active Atlantic hurricane season in recorded history, with a record 27 named storms, of which 15 became hurricanes. Seven of the hurricanes strengthened into major storms, five became Category 4 hurricanes and a record four reached Category 5 strength. Hurricane Katrina of August 2005 was the costliest and one of the deadliest hurricanes in U.S. history.Drought and WildfireWarmer temperatures could increase the probability of drought. Greater evaporation, particularly during summer and fall, could exacerbate drought conditions and increase the risk of wildfires.Warning signs today: The 1999-2002 national drought was one of the three most extensive droughts in the last 40 years. Warming may have lead to the increased drought frequency that the West has experienced over the last 30 years. The 2006 wildland fire season set new records in both the number of reported fires as well as acres burned. Close to 100,000 fires were reported and nearly 10 million acres burned, 125 percent above the 10-year average. Firefighting expenditures have consistently totaled upwards of $1 billion per year.Intense RainstormsWarmer temperatures increase the energy of the climatic system and can lead to heavier rainfall in some areas.Warning signs today: National annual precipitation has increased between 5 and 10 percent since the early 20th century, largely the result of heavy downpours. The Intergovernmental Panel on Climate Change reports that intense rain events have increased in frequency during the last 50 years and human-induced global warming most likely contributed to the trend. According to the National Oceanic and Atmospheric Administration, the Northeast region had its wettest summer on record in 2006, exceeding the previous record by more than 1 inch.

On HealthHotter weather enables deadly mosquitoes to travel greater distances; carbon dioxide in the air aggravates asthma and allergies.Deadly Heat WavesMore frequent and severe heat waves will result in a greater number of heat-related deaths.Warning signs today: In 2003, extreme heat waves claimed as many as 70,000 lives in Europe. In France alone, nearly 15,000 people died during two weeks of soaring temperatures, which reached as high as 104 degrees Fahrenheit. Much of North America experienced a severe heat wave in July 2006, which contributed to the deaths of over 140 people, including some who owned working air conditioners. In the 1995 Chicago heat wave, 739 heat-related deaths occurred in a one-week period.

Bad Air, Allergy and AsthmaGlobal warming could increase smog pollution in some areas and intensify pollen allergies and asthma. Hotter conditions could also aggravate local air quality problems, already afflicting more than 100 million Americans.Warning signs today: Scientific studies show that a higher level of carbon dioxide spurs an increase in the growth of weeds such as ragweed, whose pollen triggers allergies and exacerbates asthma. The number of pollen allergy and asthma sufferers has increased worldwide over the last several decades. Some researchers have suggested that this could be an early health effect of human-caused climate change. Air pollution makes allergies worse: Diesel exhaust particles can interact with pollen and deliver it deeper into the lung. Rising temperatures increase ground-level ozone smog production, which presents a serious threat to asthmatics.Infectious Disease and Food and Waterborne Illness OutbreaksWarming temperatures, alternating periods of drought and deluges, and ecosystem disruption have contributed to more widespread outbreaks of infections like malaria, dengue fever, tick-borne encephalitis, and diarrheal illnesses. People living in poverty will be hardest hit by the global surge in infectious diseases.Warning signs today: Disease-carrying mosquitoes are spreading as the climate allows them to survive in formerly inhospitable areas. Mosquitoes that can carry dengue fever viruses were previously limited to elevations of 3,300 feet but recently appeared at 7,200 feet in the Andes Mountains of Colombia. Malaria has been detected in new higher-elevation areas in Indonesia and Africa, posing new risks to millions of impoverished people whose health is already challenged. Heavy rainfall events can wash pathogens from contaminated soils, farms, and streets into drinking water supplies. An outbreak of diarrheal illness in Milwaukee in 1993 which affected 403,000 people was caused by the parasite Cryptosporidium, which washed into the city's drinking water supply after heavy rains. Higher outdoor temperatures can cause increased outbreaks of foodborne illnesses such as salmonella, which reproduces more rapidly as temperatures increase. Another foodborne bacteria, Vibrio parahaemolyticus, once native to subtropical regions, has expanded its range as far north as Alaska, where in 2004 it sickened unlucky cruise ship passengers when they ate raw local oysters.Dangerous Weather EventsA warmer atmosphere can hold -- and dump -- more moisture, contributing to more intense extreme weather events, which in turn put people's lives at risk.Warning signs today: Hurricane Katrina forced the evacuation of 1.7 million people in 2005, and lead to deaths and long-term health problems for 200,000 New Orleans residents. A combination of rising sea levels, reduced snowfall and increased rainstorms threatens to flood the homes of 300,000 California residents in the Sacramento-San Joaquin river delta area, potentially contaminating the drinking water of 24 million people. Alternating drought and floods have led to food and water shortages, malnutrition, mass migrations and international conflict. Some researchers suggest that 50 million people worldwide could become "environmental refugees" by 2010, displaced by rising sea levels, desertification, depleted aquifers and intermittent river flooding.On WildlifeRising temperatures ravage coral reefs and melt the habitats of polar bears and Antarctic penguins.Ecosystem Shifts and Species Die-OffIncreasing global temperatures are expected to disrupt ecosystems, pushing to extinction those species that cannot adapt. The first comprehensive assessment of the extinction risk from global warming found that more than 1 million species could be obliterated by 2050 if the current trajectory continues.Warning signs today: A recent study of nearly 2,000 species of plants and animals discovered movement toward the poles at an average rate of 3.8 miles per decade. Similarly, the study found species in alpine areas to be moving vertically at a rate of 20 feet per decade in the second half of the 20th century. The latest Intergovernmental Panel on Climate Change report found that approximately 20 to 30 percent of plant and animal species assessed so far are likely to be at increased risk of extinction if global average temperature increases by more than 2.7 to 4.5 degrees Fahrenheit. Some polar bears are drowning because they have to swim longer distances to reach ice floes. The U. S. Geological Survey has predicted that two-thirds of the world's polar bear sub-populations will be extinct by mid-century due to melting of the Arctic ice cap. In Washington's Olympic Mountains, sub-alpine forest has invaded higher elevation alpine meadows. Bermuda's mangrove forests are disappearing.

In areas of California, shoreline sea life is shifting northward, probably in response to warmer ocean and air temperatures. Over the past 25 years, some Antarctic penguin populations have shrunk by 33 percent due to declines in winter sea-ice habitat. The ocean will continue to become more acidic due to carbon dioxide emissions. Because of this acidification, species with hard calcium carbonate shells are vulnerable, as are coral reefs, which are vital to ocean ecosystems. Scientists predict that a 3.6 degree Fahrenheit increase in temperature would wipe out 97 percent of the world's coral reefs.On Glaciers and Sea LevelsArctic summers could be ice-free by 2040, and sea levels could rise as much as 23 inches by 2100 if current warming patterns continue.Melting Glaciers, Early Ice ThawRising global temperatures will speed the melting of glaciers and ice caps and cause early ice thaw on rivers and lakes.Warning signs today: After existing for many millennia, the northern section of the Larsen B ice shelf in Antarctica -- a section larger than the state of Rhode Island -- collapsed between January and March 2002, disintegrating at a rate that astonished scientists. Since 1995, the ice shelf's area has shrunk by 40 percent. According to NASA, the polar ice cap is now melting at the alarming rate of nine percent per decade. Arctic ice thickness has decreased 40 percent since the 1960s. Arctic sea ice extent set an all-time record low in September 2007, with almost half a million square miles less ice than the previous record set in September 2005, according to the National Snow and Ice Data Center. Over the past 3 decades, more than a million square miles of perennial sea ice -- an area the size of Norway, Denmark and Sweden combined -- has disappeared. Multiple climate models indicate that sea ice will increasingly retreat as the earth warms. Scientists at the U.S. Center for Atmospheric Research predict that if the current rate of global warming continues, the Arctic could be ice-free in the summer by 2040. At the current rate of retreat, all of the glaciers in Glacier National Park will be gone by 2070.

Sea-Level RiseCurrent rates of sea-level rise are expected to increase as a result both of thermal expansion of the oceans and melting of most mountain glaciers and partial melting of the West Antarctic and Greenland ice caps. Consequences include loss of coastal wetlands and barrier islands, and a greater risk of flooding in coastal communities. Low-lying areas, such as the coastal region along the Gulf of Mexico and estuaries like the Chesapeake Bay, are especially vulnerable.Warning signs today: Global sea level has already risen by 4 to 8 inches in the past century, and the pace of sea level rise appears to be accelerating. The Intergovernmental Panel on Climate Change predicts that sea levels could rise 10 to 23 inches by 2100, but in recent years sea levels have been rising faster than the upper end of the range predicted. In the 1990s, the Greenland ice mass remained stable, but the ice sheet has increasingly declined in recent years. This melting currently contributes an estimated one-hundredth of an inch per year to global sea level rise. Greenland holds 10 percent of the total global ice mass. If it melts, sea levels could increase by up to 21 feet.

what CAN WE DO TO HELP?Possible solutions to global warming range from the simple to the complex -- from changing a light bulb to engineering giant reflectors in space. The most talked about solutions involve expanded use of alternative energy technologies, and less reliance on fossil fuels.

Michael MacCracken

Climate scientist Michael MacCracken says society has to make the commitment to change. "You have to commit to taking actions that will require society to do certain things, but many of those can be beneficial and helpful, but we're going to have to change the path that we are on and how we get energy."

Step 1: Set limits on global warming pollutionWhat It Will TakeBold, visionary action from Congress. Congress needs to act now. Strong legislation that caps carbon emissions and makes polluters pay for the global warming gases they produce will mobilize billions of dollars for investment and help address our collective energy, economic and climate crises. We need to build a new energy economy that cuts global warming emissions at least 80 percent by mid-century. We have no more time to lose.Who's Doing It NowRegional Greenhouse Gas Initiative (RGGI)You'll hear doomsday scenarios about the impact that capping greenhouse gas emissions will have on our economy. But a successful, market-based carbon cap system is already alive and well in America. Ten states in the northeast and mid-Atlantic participate in the Regional Greenhouse Gas Initiative (RGGI), which will cap and reduce global warming pollution from their power plants 10 percent by 2018.Here's how it works: Electric power generators buy emissions allowances at quarterly regional auctions. The proceeds are then invested in energy efficiency programs and clean energy solutions. Three auctions have been held already. Bidders snapped up all available allowances, generating more than $247 million in revenue for energy efficiency and other clean energy investments in participating states while continuing to keep the lights on throughout the region.How We All BenefitMore jobs. Less pollution. Fewer disasters. By charging polluters, Congress could raise $100 to $150 billion annually to invest in clean energy. These investments in turn would spur the growth of a clean energy economy and create 2 million new American jobs in two years. And by making significant reductions in global warming pollution by mid-century, scientists say, we can avoid some of the most disastrous consequences of global warming, such as the melting of the Greenland ice sheet and a dramatic rise in sea levels.Step 2: Invest in green jobs and clean energy

What It Will TakeSmart investments in green, job-creating industries. Investing in clean energy industries, such as wind and solar, as well as energy efficiency programs and retooling manufacturing plants can lead us out of crisis and into a new clean energy economy.

Who's Doing It NowTroy Galloway, SteelworkerTroy Galloway lost his job at a western Pennsylvania steel mill in 2000. He got a real estate license, then started a construction company, but no matter what he tried, he had trouble bringing home a steady income."It was bad. We were scrimping," he recalls.In the spring of 2006, a Spanish wind turbine maker called Gamesa opened a plant in Ebensburg, Pa, about a half-hour drive from Galloway's home. Galloway landed a job in the finishing department, smoothing the edges of mammoth windmill blades. It was an awful lot like his first job in the steel mills. "All my skills transferred," he says."It's a feel-good job," says Galloway. "Not only is it good money and good working conditions, but you feel good because of what you're doing. You're doing something good for the environment, reducing our dependence on foreign oil, and doing something good for our children."How We All Benefit Jobs. Millions of jobs. Manufacturing solar panels and wind turbines and retrofitting homes will get American workers back on their feet and get our economy rolling again. Studies show that investing in clean energy technologies would produce more jobs than similar investments in oil and gas and these jobs can be created without increasing the federal debt. Investments in clean energy will also help end America's oil addiction and usher in a new, secure energy future.

Step 3: Drive smarter carsWhat It Will TakeBreaking our oil addiction and retooling plants to manufacture the fuel-efficient cars that consumers are demanding, including hybrids and plug-in hybrids.Who's Doing It NowPaul Scott, Santa Monica, Calif.After Paul Scott was diagnosed with cancer, he and his wife decided it was time to get around to doing some of the things they had always meant to do like installing solar panels in their home. In the course of doing research on the panels, Scott stumbled on a website about electric cars."The people posting on the site talked about it like it was the best thing ever," Scott recalls. "I decided to take one for a test drive, and one block later, I was sold. There was no noise, no vibration. And the acceleration was better than the gas version of the car."Scott's owned an all-electric Toyota RAV4 since 2002. He puts about 10,000 miles a year on the car, running it purely on sunlight. The solar panels that provide all the electricity for his home also charge his car battery."I haven't been to a gas station in more than 6 years," he says. "There's zero guilt when you drive. My money isn't buying the bombs and bullets that are killing our soldiers."Cars that drive on electricity, such as plug-in hybrids and Scott's RAV4, dramatically cut oil use, reduce global warming pollution and save money. Including the cost of the solar installation, Scott estimates he's paying just a few hundred dollars a year to power his house and his car.How We All BenefitSave on gas. High-mileage cars use less gas, helping keep American dollars at home and in our pockets. Retooling auto plants will help U.S. carmakers meet the demand for fuel-efficient cars, find profitability at home and compete once again in the global market. If we make our cars more efficient over the next ten years, we'll cut global warming pollution by more than 350 million metric tons and save 2 million barrels of oil a day.

Step 4: Create green homes and buildingsWhat It Will TakeMaking buildings more energy efficient. Buildings and the appliances within them account for 40 percent of America's energy use and a third of our global warming emissions. New buildings should meet strong new energy-efficiency standards that maximize energy savings. And existing homes and commercial spaces can be retrofitted to save energy by weatherizing and installing energy efficient heating, cooling and lighting systems.Who's Doing It NowApril Capil, Pleasant Hill, Calif.When April Capil and her sister came into a little money, they thought of paying down some of their mortgage -- or making some improvements to their drafty 50-year-old house. "Every winter we would be huddled up against the wall heater, my sister on one side and me on the other," Capil recalls. "We had to turn the oven on and bake cookies to make the kitchen warm. And in the summer we would sleep in the living room because the rest of the house was so hot."Capil hired a home retrofit company called Sustainable Spaces to assess the energy efficiency of her 1,000-square-foot home. They installed a new Energy Star furnace and air conditioner, insulated her attic and sealed leaks where energy was escaping. "We had these can lights in the living room which were basically holes in the ceiling," says Capil. "They replaced them with some energy efficient lights that were just as nice."Today, Capil's monthly energy bills are down from $150 to just $40 or $50 and she's not forced to bake cookies to stay warm. "What I notice most is the comfort," she says. "The temperature in my home only varies a few degrees, even when the heating or cooling system is off. I would totally recommend this."How We All BenefitCost savings. Outside of your mortgage, the next biggest cost of homeownership is heating and cooling your home. An average retrofitted home can save $700 to $1150 a year in energy costs. On a national scale, the benefits are huge. Retrofitting just one out of every 5 American homes would avoid the need to build 13 mid-sized power plants every year. Retrofitting every house in the country would cut as much global warming pollution as taking a half a million cars off the road and would save more oil and gas than we could extract from drilling in our coastal waters.

Step 5: Build better communities and transportationWhat It Will TakeBuilding walkable communities near transportation hubs instead of far-flung, car-dependent suburbs. We also need to invest in and expand public transit -- such as commuter rail -- to give people real transportation choices.Who's Doing It NowAtlantic Station, Atlanta, GeorgiaWhat do people in Atlantic Station do with all that extra time? While their counterparts in the Atlanta metro area drive an average of 34 miles a day and have one of the costliest commutes in the nation -- residents of this redeveloped former steel mill in midtown Atlanta drive only 8 miles a day.That reduced drive time is no fluke. Atlantic Station, which officially opened in October 2005, was built using principles of smart growth, a movement that espouses the environmental, social and health benefits of compact, walkable communities. Atlantic Station is a city within a city, with 5,000 homes, restaurants, shops, movie theaters, hotels, parks and office buildings all within walking distance.The development is one of the stars of the smart growth movement -- and it's not just the policy wonks who are pleased. "Our friends love to hang out here," resident Rob Padgett told the Atlanta Journal-Constitution in October 2008. "By far the best thing is having access to what we use the most. I walk to the gym, and I probably go to [the supermarket] three or four times a week. It's nice just being able to walk out and not get in the car, not put the baby in the car seat. It's wonderful."How We All BenefitShorter drive times, less pollution. Less time behind the wheel means less money spent on gas -- and more time for you. Plus, studies show that a neighborhood where people walk more is healthier, safer and friendlier. And when people can walk to the store, the office, or the movie theater instead of driving, we slow down global warming. Each "smart growth" community reduces global warming pollution by 20 to 40 percent compared to the norm.

Top 50 Things To Do To Stop Global WarmingGlobal Warming is a dramatically urgent and serious problem. We don't need to wait for governments to find a solution for this problem: each individual can bring an important help adopting a more responsible lifestyle: starting from little, everyday things. It's the only reasonable way to save our planet, before it is too late.Here is a list of 50 simple things that everyone can do in order to fight against and reduce the Global Warming phenomenon: some of these ideas are at no cost, some other require a little effort or investment but can help you save a lot of money, in the middle-long term!1. 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.We recommend you purchase your CFL bulbs at 1000bulbs.com, they have great deals on both screw-in and plug-in light bulbs.

2. Install a programmable thermostatProgrammable 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.

3. Move your thermostat down 2 in winter and up 2 in summerAlmost 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.

4. Clean or replace filters on your furnace and air conditionerCleaning a dirty air filter can save 350 pounds of carbon dioxide a year.

5. Choose energy efficient appliances when making new purchasesLook for the Energy Star label on new appliances to choose the most energy efficient products available.

6. Do not leave appliances on standbyUse the "on/off" function on the machine itself. A TV set that's switched on for 3 hours a day (the average time Europeans spend watching TV) and in standby mode during the remaining 21 hours uses about 40% of its energy in standby mode.

7. Wrap your water heater in an insulation blanketYoull 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 50C.

8. Move your fridge and freezerPlacing them next to the cooker or boiler consumes much more energy than if they were standing on their own. For example, if you put them in a hot cellar room where the room temperature is 30-35C, energy use is almost double and causes an extra 160kg of CO2 emissions for fridges per year and 320kg for freezers.

9. Defrost old fridges and freezers regularlyEven better is to replace them with newer models, which all have automatic defrost cycles and are generally up to two times more energy-efficient than their predecessors.

10. Don't let heat escape from your house over a long periodWhen airing your house, open the windows for only a few minutes. If you leave a small opening all day long, the energy needed to keep it warm inside during six cold months (10C or less outside temperature) would result in almost 1 ton of CO2 emissions.

11. Replace your old single-glazed windows with double-glazingThis requires a bit of upfront investment, but will halve the energy lost through windows and pay off in the long term. If you go for the best the market has to offer (wooden-framed double-glazed units with low-emission glass and filled with argon gas), you can even save more than 70% of the energy lost.

12. Get a home energy auditMany 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.

13. Cover your pots while cookingDoing so can save a lot of the energy needed for preparing the dish. Even better are pressure cookers and steamers: they can save around 70%!

14. Use the washing machine or dishwasher only when they are fullIf you need to use it when it is half full, then use the half-load or economy setting. There is also no need to set the temperatures high. Nowadays detergents are so efficient that they get your clothes and dishes clean at low temperatures.

15. Take a shower instead of a bathA shower takes up to four times less energy than a bath. To maximize the energy saving, avoid power showers and use low-flow showerheads, which are cheap and provide the same comfort.

16. Use less hot waterIt 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.

17. Use a clothesline instead of a dryer whenever possibleYou can save 700 pounds of carbon dioxide when you air dry your clothes for 6 months out of the year.

18. Insulate and weatherize your homeProperly 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. Energy Efficient has more information on how to better insulate your home.

19. Be sure youre recycling at homeYou can save 2,400 pounds of carbon dioxide a year by recycling half of the waste your household generates.

20. Recycle your organic wasteAround 3% of the greenhouse gas emissions through the methane is released by decomposing bio-degradable waste. By recycling organic waste or composting it if you have a garden, you can help eliminate this problem! Just make sure that you compost it properly, so it decomposes with sufficient oxygen, otherwise your compost will cause methane emissions and smell foul.

21. Buy intelligentlyOne bottle of 1.5l requires less energy and produces less waste than three bottles of 0.5l. As well, buy recycled paper products: it takes less 70 to 90% less energy to make recycled paper and it prevents the loss of forests worldwide.

22. Choose products that come with little packaging and buy refills when you canYou will also cut down on waste production and energy use... another help against global warming.

23. Reuse your shopping bagWhen shopping, it saves energy and waste to use a reusable bag instead of accepting a disposable one in each shop. Waste not only discharges CO2 and methane into the atmosphere, it can also pollute the air, groundwater and soil.

24. Reduce wasteMost products we buy cause greenhouse gas emissions in one or another way, e.g. during production and distribution. By taking your lunch in a reusable lunch box instead of a disposable one, you save the energy needed to produce new lunch boxes.25. Plant a treeA 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.

26. Switch to green powerIn many areas, you can switch to energy generated by clean, renewable sources such as wind and solar. In some of these, you can even get refunds by government if you choose to switch to a clean energy producer, and you can also earn money by selling the energy you produce and don't use for yourself.

27. Buy locally grown and produced foodsThe 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.

28. Buy fresh foods instead of frozenFrozen food uses 10 times more energy to produce.

29. Seek out and support local farmers marketsThey reduce the amount of energy required to grow and transport the food to you by one fifth. Seek farmers markets in your area, and go for them.

30. Buy organic foods as much as possibleOrganic 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, wed remove 580 billion pounds of carbon dioxide from the atmosphere!

31. Eat less meatMethane 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.

32. Reduce the number of miles you drive by walking, biking, carpooling or taking mass transit wherever possibleAvoiding just 10 miles of driving every week would eliminate about 500 pounds of carbon dioxide emissions a year! Look for transit options in your area.

33. Start a carpool with your coworkers or classmatesSharing 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 service connecting north american commuters and travelers.34. Don't leave an empty roof rack on your carThis can increase fuel consumption and CO2 emissions by up to 10% due to wind resistance and the extra weight - removing it is a better idea.

35. Keep your car tuned upRegular 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.

36. Drive carefully and do not waste fuelYou can reduce CO2 emissions by readjusting your driving style. Choose proper gears, do not abuse the gas pedal, use the engine brake instead of the pedal brake when possible and turn off your engine when your vehicle is motionless for more than one minute. By readjusting your driving style you can save money on both fuel and car mantainance.

37. Check your tires weekly to make sure theyre properly inflatedProper tire 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!

38. When it is time for a new car, choose a more fuel efficient vehicleYou 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 on FuelEconomy and on GreenCars websites.

39. Try car sharingNeed a car but dont 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.

40. Try telecommuting from homeTelecommuting can help you drastically reduce the number of miles you drive every week. For more information, check out the Telework Coalition.

41. Fly lessAir 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 carbon emissions by investingin renewable energy projects.

42. Encourage your school or business to reduce emissionsYou can extend your positive influence on global warming well beyond your home by actively encouraging other to take action.

43. Join the virtual marchThe Stop Global Warming Virtual March is a non-political effort to bring people concerned about global warming together in one place. Add your voice to the hundreds of thousands of other people urging action on this issue.

44. Encourage the switch to renewable energySuccessfully 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. U.S. citizens, take action to break down those barriers with Vote Solar.

45. Protect and conserve forest worldwideForests play a critical 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 saving forests from global warming.

46. Consider the impact of your investmentsIf you invest your money, you should consider the impact that your investments and savings will have on global warming. Check out SocialInvest and Ceres to can learn more about how to ensure your money is being invested in companies, products and projects that address issues related to climate change.

47. Make your city coolCities and states around the country have taken action to stop global warming by passing innovative transportation and energy saving legislation. If you're in the U.S., join the cool cities list.

48. Tell Congress to actThe 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.

49. Make sure your voice is heard!Americans must have a stronger commitment from their government in order to stop global warming and implement solutions and such a commitment wont 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!50. Share this list!Send this page via e-mail to your friends! Spread this list worldwide and help people doing their part: the more people you will manage to enlighten, the greater YOUR help to save the planet will be (but please take action on first person too)!