WASHINGTON — Directly contradicting much of the Trump administration’s position on climate change, 13 federal agencies unveiled a scientific report Friday that says humans are the dominant cause of the global temperature rise that has occurred since the start of the 20th century, creating the warmest period in the history of civilization.
Over the past 115 years, global average temperatures have increased 1.8 degrees, leading to record-breaking weather events and temperature extremes, the report says.
The global, long-term warming trend is “unambiguous,’’ it says, and there is “no convincing alternative explanation’’ that anything other than humans — the cars we drive, the power plants we operate, the forests we destroy — are to blame.
The report was approved for release by the White House, but the findings come as the Trump administration is defending its climate change policies on several fronts.
The United Nations convenes its annual climate change conference next week in Bonn, Germany, and the US delegation is expected to face harsh criticism over President Trump’s decision to walk away from the 195-nation Paris climate accord and top administration officials’ stated doubts about the causes and impacts of a warming planet.
“This report has some very powerful, hard-hitting statements that are totally at odds with senior administration folks and at odds with their policies,’’ said Philip B. Duffy, president of the Woods Hole Research Center.
“Where are members of the administration getting their information from? They’re obviously not getting it from their own scientists,’’ Duffy said.
The climate science report is part of a congressionally mandated review conducted every four years known as the National Climate Assessment. The product of hundreds of experts within the government and academia and peer-reviewed by the National Academy of Sciences, it is considered the United States’ most definitive statement on climate change.
In other White House developments Friday:
■ Corruption inquiries. President Trump pressed the Justice Department again Friday to investigate his political opponents, lashing out at Democrats as he argued that they were the ones who acted corruptly during last year’s election and not his own campaign, which is under investigation.
Shortly before leaving on a trip to Asia, Trump issued a name-calling blizzard of accusations at Democratic leaders and railed at law enforcement agencies that have refused to prosecute them, even as he acknowledged that presidents are not supposed to intervene in law enforcement decisions.
“I’m really not involved with the Justice Department. I’d like to let it run itself,’’ he told reporters. “But honestly, they should be looking at the Democrats.’’
He again turned to the name calling that has characterized his political career, assailing “Crooked Hillary,’’ “Crazie Bernie’’ Sanders, and “Pocahontas,’’ a derisive name he has used for Senator Elizabeth Warren, the Massachusetts Democrat.
He said Clinton “stole the Democratic primary’’ from Sanders, saying there was violation of campaign finance laws and money laundering.’’
■ Tax overhaul. The House’s leading tax bill negotiator opened the possibility that the push by Congress to cut taxes could mesh with its so-far failed effort to repeal the Affordable Care Act.
Representative Kevin Brady, Republican of Texas, chairman of the House Ways and Means Committee, said the tax bill could include a measure to do away with the health law’s mandate that most Americans have health coverage.
Brady said no decision had been made about whether to include repeal of the individual mandate, as Trump wants.
