Global warming refers to the increasing average temperature of Earth’s atmosphere and oceans over time.
There is scientific consensus that global warming is occurring and that it is caused by humans. There are no peer-reviewed scientists that dispute this fact.
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Global warming occurs because of the greenhouse effect. When sunlight enters the atmosphere, much of it is absorbed by Earth’s surface. As the planet cools, that energy is released as infrared radiation, or heat.
Greenhouse gases like carbon dioxide, nitrous oxide, methane, and water vapor capture infrared radiation and re-emit it in all directions, warming the Earth’s surface and lower atmosphere.
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The greenhouse effect is a natural process that is necessary to make Earth habitable. However, as concentrations of greenhouse gases in the atmosphere increase, the warming effect becomes magnified, causing rising temperatures and disastrous consequences for the planet.
Levels of greenhouse gases in the atmosphere have risen dramatically since the start of the Industrial Revolution. Scientists agree that human activity is the cause.
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Concentrations of nitrous oxide have risen 18 percent from pre-industrial levels, while atmospheric methane has more than doubled.
Carbon dioxide (CO2) is the biggest contributor to global warming. CO2 concentrations have risen by forty percent from pre-industrial levels
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Humans release more than 30 billion tons of CO2 each year, primarily through the burning of fossil fuels. In the United States, coal plants are the single largest source of carbon pollution.
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Currently, levels of CO2 in the atmosphere stand at around 395 parts per million, higher than any recorded level in at least the past 800,000 years.
Explore this interactive Gapminder graph to track the increase of atmospheric CO2 over time.
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Over the past century, global surface temperatures have risen at an average rate of .13 degrees per decade. Since the 1970s, the rate of warming has increased to between .35 and .51 degrees per decade. The rate of warming over the continental United States has risen dramatically since the 1970s to nearly double the global rate.
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Scientists predict that temperatures will rise by another 2-11.5 degrees over the next century, depending on the rate of GHG emissions. US temperatures are expected to rise by 4-11 degrees by 2100.
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Since, carbon dioxide can stay in the atmosphere for hundreds of years, even if CO2 production ceased tomorrow, warming will continue for hundreds of years.
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Scientists agree that it is vital to cap the temperature increase at 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels. After this point, warming may trigger irreversible effects.
The International Energy Agency predicts that world leaders have until 2017 to reduce CO2 emissions enough to avoid a 2 degree temperature increase.
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Arctic sea ice reaches its annual minimum in September. The satellite images above show September Arctic sea cie in 1979, the first year these data were available, and 2007.
Warmer temperatures cause glaciers, ice caps, and portions of the Greenland and Antarctic ice sheets to melt, resulting in sea level rise.
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After 2,000 years of little change, global sea level has risen by 8 inches since 1870.
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Predictions for future sea level rise vary by coastal area and depend on the rate of melting, but recent studies suggest that sea levels on the East coast of North America are rising at a faster rate than average and could result in a 5 foot increase by the end of the century.
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The United Nations High Commission for Refugees estimates that sea-level rise could displace hundreds of millions of people living in coastal cities.
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Extinction is possibly the most permanent impact of global warming. A 3-5 degree increase in temperature could result in the extinction of up to 30 percent of all species.
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Due to a combination of human-induced factors, the current extinction rate is 1,000 times higher than the average extinction rates of Earth’s history.
Other effects of global warming on ecosystems include: species range shifts, food web disruptions, and migration disruptions
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Ocean acidity increases as CO2 is absorbed by the oceans, lowering the water’s pH. Since pre-industrial times, the oceans have experienced a 25 percent increase in acidity.
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Ocean acidification threatens marine life like corals, mollusks, and shellfish by decreasing the availability of calcium carbonate.
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Global warming will make extreme weather events more likely, an effect we are already seeing today.
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Scientists believe rising temperatures will bring stronger and more frequent storms, wildfires, droughts, floods, hurricanes and deadly heat waves.
For more on dangerous heat in the Midwest, see Union of Concerned Scientists report Heat in the Heartland
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Global warming will contribute to a variety of health problems for humans. Extreme weather, especially heat, will increase mortality and exacerbate illnesses around the world.
For more, see the CDC’s Climate and Health page.
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There are many personal steps we can each take to reduce our impact on the planet, from changing a light bulb to driving a more fuel-efficient car.
Calculate your ecological footprint here to see what changes you can make to reduce your contribution to global warming.
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However, in addition to personal action, large-scale political solutions are absolutely necessary to minimize the impacts of global warming.
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“Why I Must Speak Out About Climate Change”- Watch Climate Scientist James Hansen’s ‘Ted Talk’ at http://tinyurl.com/JamesHansenTED.
There has been consensus among scientists for years that global warming is a serious problem and that it is caused by human activity. This page contains links and scientific information on global warming.
Global warming refers to an increase in the average temperature of the Earth’s atmosphere and oceans over time. This temperature rise is the result of an increase in carbon dioxide and other greenhouse gases, including methane, nitrous oxide and aerosols, in our atmosphere.
When sunlight strikes the Earth’s surface, some of it is reflected back towards space as infrared radiation or heat. Greenhouse gases absorb this infrared radiation and trap the heat in the atmosphere. Normal amounts of gases are what keep the Earth warm and habitable. However, the build up of gasses beyond the normal levels and at a rate that the environment cannot alleviate, is what causes global warming. Surface air temperatures and sub-surface ocean temperatures are rising and are expected to continue to rise.
Learn the basics with University of Michigan scientist and ELPC adviser Knute Nadelhoffer in this video:
For an excellent overview of the basic science and effects of global warming, visit the Pew Center’s website.
Plant productivity and vitality will change, destroying fragile ecosystems. The record highs of atmospheric gases are the result of burning fossil fuels, clearing of land and agriculture activity. According to most experts, the sharp increase of dramatic warming in the past 50 years is attributable to human activity. In the United States, energy-related carbon dioxide emissions, resulting from petroleum and natural gas, represents 82 percent of our total human-made greenhouse gas emissions.
Global warming is more than just glaciers and polar bears. The Great Lakes is the largest freshwater body of water on the planet, the single largest source of surface fresh water in the world. Scientists estimate that the lakes are warmer and water levels are declining, with no end in sight.
The Midwest is at the center of our global warming problems and can be at the center of our solutions.
Illinois, Indiana, Iowa, Michigan, Ohio and Wisconsin account for 20% of the carbon pollution in the United States with only 5% of the world’s total pollution. The Midwest alone is responsible for more global warming pollution than most countries across the globe except for China, India, Russia and Japan. There are several factors that make the Midwest critical to global warming solutions:
The Midwest has the largest concentration of old, dirty coal plants that produce large amounts of carbon dioxide which cause global warming.
As the hub on the United States transportation industry, the crossroads of America has developed a heavy carbon burden.
Clean technologies mean a cleaner world for all. Not only do modern technologies reduce carbon pollution, they reduce other harmful pollutants that poison our lakes, make our land infertile, and harm human health. By reducing global warming pollution, we help to make our energy and transportation systems more efficient, protect our forest ecosystems, wildlife and biodiversity, and improve our air quality and protect peoples’ health.
We need the political and economic capital to make clean energy decisions happen today. For example, renewable energy, such as wind and others, currently supplies about 2% of the region’s electricity supply. We have the technology to meet 20% of our energy supply needs through clean, renewable energy. The result – a 51% reduction in carbon dioxide – is a larger reduction than proposed by the Kyoto Treaty.
Clean car technology can produce more efficient, less polluting cars that get better mileage and create needed manufacturing jobs. We have the technology to clean up dirty diesel trucks and use cleaner fuels – but we can only achieve success by avoiding roadblocks and creating policies that reduce pollution.
It is our moral imperative to address our carbon consumption for today’s world and generations to come. With current technologies, policies and personal actions we can take a huge take step forward in securing our energy future with homegrown business and innovation while protecting our natural resources.
In June of 2009 the House of Representatives successfully passed the American Clean Energy and Security Act, a comprehensive plan to transition America to a clean energy economy and reduce carbon pollution. Now it is time for the U.S. Senate to draft their version of national energy and climate legislation. Please urge your Senators to write legislation that expands and improves the House version of the bill. Read a summary of the American Clean Energy and Security Act here.