The National Climate Assessment finds the U.S. average temperature has increased by as much as 1.9 degrees Fahrenheit since record keeping began in 1895, and most of that increase has occurred since the 1970s.
"The global warming of the past 50 years is primarily due to human activities, predominantly the burning of fossil fuels," the report finds.
The 840-page report said that climate change has "moved firmly into the present," with the economies in all U.S. territories feeling the impact.
"This National Climate Assessment concludes that the evidence of human-induced climate change continues to strengthen and that impacts are increasing across the country," it said.
The report finds the amount of warming projected during the next few decades is linked directly to emissions of greenhouse gasses. It finds temperatures by the end of the century will be at least 3 degrees Fahrenheit warmer than today under a best case scenario, and as much as 10 degrees Fahrenheit warmer on the high end, "assuming continued increases in emissions, predominantly from fossil fuel combustion."
The conservative Cato Institute said the report is biased toward the negative.
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