Human-induced global climate change—is emerging as the single most dangerous and pervasive threat of all to ecosystems and the flows of ecosystem services around the world. A changing climate will affect ecosystems, weather, crop production, insect and pest populations, and human health. Climate shifts are the most dramatic and disturbing they have been: after over a thousand years of 280ppm concentrations of carbon dioxide, these concentrations are now at 385 ppm. Scientists agree that median temperatures would increase 5.1 degrees Celsius by 2100.
A consensus has existed since the early 90s among scientists that climate change is happening, it is real, and it is human-induced. Naomi Oreskes in Merchants of Doubt: How A Handful of Scientists Obscure the Truth provides a good synopsis of the debate about climate change: http://www.youtube.com/watch?v=XXyTpY0NCp0
Al Gore’s epic An Inconvenient Truth, even though it has come under fire from naysayers, is worth viewing. It outlines the causes, research and debates to date: http://video.google.com/videoplay?docid=8847562857479496579
Current consumption patterns and use of greenhouse gas-producing energy are driving factors in increased levels of carbon dioxide concentrations. Policy and laws alone are not enough to shift this dramatic change in climate; a fundamental change in the way humans conduct business, and live will be essential.
— Anukriti Sud Hittle