Washington (AFP) - The US government released Friday a major scientific report that says climate change is real, "extremely likely" to be caused by human activity, and affecting the daily lives of Americans.

The findings of the federally mandated report are starkly at odds with the position of US President Donald Trump, who has labeled global warming a Chinese hoax and named fossil fuel ally Scott Pruitt to head the Environmental Protection Agency.

The Climate Science Special Report spans more than 600 pages and is part of a larger report known as the Fourth National Climate Assessment.

Based on "a large body of scientific, peer-reviewed research," global annually averaged surface air temperature has increased by about 1.8 Fahrenheit (1.0 Celsius) over the last 115 years (1901–2016), it says.

"This period is now the warmest in the history of modern civilization," said the report, available at https://science2017.globalchange.gov.

It was compiled by the National Oceanographic and Atmospheric Administration, with contributions from NASA, the Department of Energy and other federal agencies.

Since the last report of its kind was issued in 2014, "stronger evidence has emerged for continuing, rapid, human-caused warming of the global atmosphere and ocean," it said.

"It is extremely likely that human activities, especially emissions of greenhouse gases, are the dominant cause of the observed warming since the mid-20th century has been the dominant cause of the observed warming since the mid-20th century," the report added, noting there "is no convincing alternative explanation."

After examining long-term climate records and data going back thousands of years, the report said that in the modern era, "average temperatures in recent decades over much of the world have been much higher, and have risen faster during this time period than at any time in the past 1,700 years or more."

The findings came as no surprise to climate scientists.

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"This isn't new," said Peter Gleick, president-emeritus of the Pacific Institute and a member of the US National Academies of Science.

"This is news only because Trump couldn't censor it," he said on Twitter.

The Trump administration has repeatedly denied or downplayed the role of fossil fuels in global warming.

EPA chief Pruitt shocked scientists earlier this year when he argued in a media interview that carbon dioxide was not a primary contributor to global warming.

The NOAA said the report "serves as the foundation for efforts to assess climate-related risks and inform decision-making about responses."

The last report of its kind came out in May 2014.

Democratic Senator Al Franken of Minnesota and eight of his colleagues this week sent a letter to Trump asking "what safeguards are in place to ensure that the National Climate Assessment and the Climate Science Special Report give fair and accurate summations of the latest climate science without political interference."

The senators also asked how the Trump Administration plans to address the report's findings.