Humanity is fundamentally changing the planet by pumping greenhouse gases into the atmosphere, US government scientists said on 3 November in their latest assessment of climate science.
The average global temperature has increased by 1 °C since the pre-industrial era, the 477-page report says — adding that the past 115 years comprise the warmest period “in the history of modern civilization” (see go.nature.com/2hpj3bo). The analysis warns that temperatures could increase by another 4 °C by the end of the century, with dramatic consequences for people and ecosystems.
The findings are at odds with the policies of US President Donald Trump, who has questioned established climate science and vowed to protect and promote the country’s fossil-fuel industry. Trump’s stances led many scientists to worry that his administration would try to block or tamper with the climate-change assessment, but several scientists who helped to write the document reported that they experienced no problems.
“We weren’t interfered with, and we ended up producing something that I think is of tremendous value,” says David Fahey, an atmospheric scientist with the National Oceanic and Atmospheric Administration in Boulder, Colorado, and a coordinating lead author.
The climate-science report is the first volume of the next National Climate Assessment, a legally mandated analysis of the causes and impacts of global warming that is due in 2018. The second volume, released in draft form on 3 November, focuses on how climate change is affecting life in the United States, from crop yields to property damage caused by extreme weather. Another report, on the carbon cycle, was released in draft form on the same day. The US National Academy of Sciences is set to review the draft documents.
“The science speaks for itself,” says Don Wuebbles, a climate scientist at the University of Illinois at Urbana-Champaign and a coordinating lead author of the climate-science report. “It’s hard to counteract the basic observations and the truth of the science with any kind of political playing around.”
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Tollefson, J. US climate report stresses human role. Nature 551, 152 (2017). https://doi.org/10.1038/nature.2017.22929