Every six years, the United Nations-sponsored Intergovernmental Panel on
Climate Change (IPCC) releases a massive and influential study
detailing the state of Earth's climate. Every citizen on the planet
should take the 20 minutes needed to read the Summary for Policy Makers (PDF File)
issued in February 2007. In their fourth report since 1990, the IPCC
offered its strongest language yet that Earth's climate is warming and
humans are largely responsible:
