Global Warming and Climate Change

What is global warming?

Global warming refers to a rise in average global temperature due to human activities: namely, the emissions of greenhouse gases produced by the burning of fossil fuels, and land-use changes like deforestation.

How does global warming function?

Heat from the sun passes through our atmosphere where it is absorbed by the Earth's surface.  Some of that heat is reflected back to space.  Greenhouse gases in our atmosphere trap a portion of this reflected heat, preventing it from escaping, thus keeping the earth warmer than it otherwise would be.  A majority of this greenhouse effect is natural, maintaining Earth's average temperature at about 60F (15C). Without the natural greenhouse effect, Earth's average temperature would be closer to 0F (-18C).

There is a worldwide consensus among scientists that the global average temperature has risen about 1F (0.4C-0.8C) in the past 140 years.  Assessments by the U.S. National Academy of Sciences and the United Nations' Intergovernmental Panel on Climate Change (IPCC) find that most of the warning of the past 50 years is likely due to the accumulation of greenhouse gases.

The atmospheric concentration of several greenhouse gases are rising as a result of human activity.  Carbon dioxide, the most important human-made greenhouse gas, is released primarily by the burning of fossil fuels like coal, oil, and natural gas; CO2 concentration has risen by 30% over its value in pre-industrial times.

What is the future of global warming?

According to the IPCC, Earth may warm by 2.5F to 10.4F (1.4C-5.8C) by the end of this century, potentially making our planet warmer than at any time since dinosaurs were dominant.  The difference in global average temperature between modern times and the last ice age - when much of Canada and the northern United States were covered with a thick ice sheet - was only about 9F (5C). A temperature rise of similar magnitude could have serious, potentially devastating effects on society and ecosystems.

Scientists project that Earth could experience the fastest warming in the history of civilization during the 21st century.  These higher temperatures will probably be accompanied by an increase in extreme weather events such as flooding and drought, as well as global sea-level rise.  While the first signs of global warming are apparent now, a sharp reduction of greenhouse gas emissions can significantly slow global warming.

For more information go to www.fightglobalwarming.com