|What do the experts say?
According to the Intergovernmental Panel on Climate Change (IPCC), an organization made up of hundreds of the world’s top scientists and policy experts, there is no doubt that that the earth is warming. In their most recent report, the IPCC states, “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level” (IPCC, 2007, Summary for Policymakers, Working Group I)
What is climate change?
Climate change, as defined by the IPCC, is "any change in climate over time, whether due to natural variability or as the result of human activity."
There is no doubt that Earth’s climate fluctuates naturally over time, as can be seen clearly in the geological record. Solar activity, the earth’s orbit, ocean circulation, volcanic activity, and changes to the chemical composition of the atmosphere all influence Earth’s climate. While past climate change undoubtedly occurred without human influence, there is little doubt among the world’s top scientists that human activity is the main cause of the global warming evident in recent decades.
A summary of some of the IPCC’s most recent findings:
· Climate Change: Observations and Predictions
· Key Impacts on the Environment
The Greenhouse Effect.
The Greenhouse Effect is a natural process that warms the Earth, and, in fact, is quite necessary for our survival. Gases in the atmosphere, like water vapor (clouds), carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) act as a natural blanket by preventing the sun’s heat energy from radiating back into space, much like a greenhouse in the photo below traps the sun’s energy to help plants grow even in the middle of winter. In fact, the natural greenhouse effect helps warm the Earth’s surface by as much as 33oC, and without it, our planet would be too cold for humans to survive.
The Intergovernmental Panel on Climate Change (IPCC) is currently finalizing its Fourth Assessment Report "Climate Change 2007,"* widely recognized among scientists, policymakers, and government officials as the most complete and comprehensive scientific assessment of climate change to date. Hundreds of scientific experts from all over the world contribute to the IPCC’s reports as authors, contributors, and reviewers. To read each of the IPCC’s Working Groups’ reports, click on the links below.
The Synthesis Report
Working Group I Report “The Physical Science Basis”
Working Group II Report “Impacts, Adaptation and Vulnerability”
Working Group III Report “Mitigation of Climate Change”