About Global Warming
Global warming is a profound threat to both humanity and the natural world, and one of the most serious challenges humankind has ever faced. The atmospheric concentration of carbon dioxide—the heat-trapping gas primarily responsible for global warming—has reached levels the planet has not experienced for eight hundred thousand years, and as a result the global mean temperature has risen for more than a century. The international Intergovernmental Panel on Climate Change, the National Academies of Science in the United States and scientific academies in 10 other nations have all stated that human activity, especially the burning of fossil fuels in cars and power plants, is a major driver of this warming trend since 1950.
The 2007 report of the Intergovernmental Panel on Climate Change unequivocally concluded that our climate is warming, stating with at least 90 percent certainty that the warming of the last several decades is primarily due to human activities. Global average temperatures have already risen ˜ 0.7°C (1.3°F) over the last 100 years, and impacts are now being observed worldwide. Human-caused emissions to date have locked in further changes including sea-level rise that will intensify coastal flooding, and dramatic reductions in snowpack that are likely to disrupt water supplies in the western United States. If emissions continue unabated, our nation and the world will face more sea level rise, heat waves, droughts, wildfires, snowmelt, flood risk, and public health threats, as well as increased rates of plant and animal species extinctions.
Scientists are acutely aware that the window for reducing global warming emissions to reasonably safe levels is closing quickly. Several recent analyses have concluded that, to avoid dangerous climate change, the United States and industrialized nations will need to reduce emissions at least 80 percent by mid-century, compared with 2000 levels—and that national and international policies must be in place within the next 5 to 10 years to achieve this ambitious outcome.
Thus, a profound transformation of the ways in which we generate and consume energy must begin now, and the urgency of this situation demands that we consider all of the options for minimizing climate change. We are obligated by our fundamental responsibility to future generations and our shared role as stewards of this planet to confront climate change in a timely and effective manner. Educating the public, by submitting an essay or photograph for this book, is one way you can help.