Scientists have spent the past six years combing the seas, skies, land and space for data on climate change
ix years is not a long time in science. Data may be collected, a paper or two published or a PhD earned. But in the six years since the last Intergovernmental Panel on Climate Charge (IPCC) report was released, the science and certainty of global warming has grown markedly. "In the first IPCC report in 1990 there were no real observations demonstrating that climate had changed, only a prognosis that it would change," says Herve Le Treut, atmospheric physicist at CNRS (France's National Center for Scientific Research) and a lead author of part of the fourth IPCC report set to be released on Friday. "By 2001, there were many signs that climate is changing and now we are already seeing the patterns described in the first IPCC report."
Simple observation confirms the basic science of climate change. "All six years since the last report (2001 to 2006) are among the seven warmest years on record," notes Kevin Trenberth, head of the Climate Analysis Section at the U.S. National Center for Atmospheric Research (NCAR) and another lead author. "Northern Hemisphere snow cover has decreased and Arctic Sea ice has been at record low levels in the past three years."



