The study is the most comprehensive report on climate change that has ever been put together. The conclusion: Evidence is clear that the earth is warming and humans are to blame.
Several hundred researchers gathered climate data on the world's oceans, ice packs and land masses.
The Intergovernmental Panel on Climate Change published the first new report since 2007. Some findings were expected. Ice caps are melting, rain patterns are changing, and carbon dioxide emissions continue to drive climate change.
But the earth's average temperature has held steady for 15 years, prompting scientific debate over what that means. While the meaning of that finding is being argued, the report makes it clear the climate is warming. Scripps Institution of Oceanography researcher Dean Roemmich said that is no longer debated.
"The debate has shifted out of the 'is it changing arena' to 'why is it changing' arena; to what extent is it anthropogenic versus natural? And the IPCC report gives very strong evidence that it is anthropogenic," Roemmich said.
And those human-caused impacts are having real world effects in California. Scripps scientist Lynne Talley says the wildfire risk is growing and water resources are shrinking.
"The snow pack in the Sierra, which is the source of a lot of our water, is melting earlier and there's less of it," said Talley an oceanographer. "And so the state is having to carefully rethink how to do its water resources."
The U.N. climate report is issued every six years. Researchers predict the next study will have a much sharper view of long-term climate trends.
