IN LATE 2007, the Intergovernmental Panel on Climate Change (IPCC), comprising thousands of scientists from around the world, published its fourth assessment on climate change, warning the nations of the world that evidence of global warming is “unequivocal” and that the link between human activities (primarily the burning of fossil fuels) and rising worldwide temperatures can be stated with “very high confidence.”
For that many scientists to agree on such a strong statement requires thousands of measurements, studies, and experiments. It should surprise no one that the scientists of the IPCC have edged slowly toward this pronouncement over the past 20 years as the evidence mounted.