WASHINGTON – The Trump administration released a dire scientific report Friday calling human activity the dominant driver of global warming, a conclusion at odds with White House decisions to withdraw from a key international climate accord, champion fossil fuels and reverse Obama-era climate policies.
To the surprise of some scientists, the White House did not seek to prevent the release of the government’s National Climate Assessment, which is mandated by law. The report affirms that climate change is driven almost entirely by human action, warns of a worst-case scenario where seas could rise as high as eight feet by the year 2100, and details climate-related damage across the United States that is already unfolding as a result of an average global temperature increase of 1.8 degrees Fahrenheit since 1900.
“It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century,” the document reports. “For the warming over the last century, there is no convincing alternative explanation supported by the extent of the observational evidence.”
The report’s release underscores the extent to which the machinery of the federal scientific establishment, operating in multiple agencies across the government, continues to grind on even as top administration officials have minimized or disparaged its findings. Federal scientists have continued to author papers and issue reports on climate change, for example, even as political appointees have altered the wording of news releases or blocked civil servants from speaking about their conclusions in public forums. The climate assessment process is dictated by a 1990 law that Democratic and Republican administrations have followed.
The White House on Friday sought to play down the significance of the study and its findings.
“The climate has changed and is always changing. As the Climate Science Special Report states, the magnitude of future climate change depends significantly on ‘remaining uncertainty in the sensitivity of Earth’s climate to [greenhouse gas] emissions,’ ” White House spokesman Raj Shah said in a statement.
Shah added that the Trump administration will continue to “promote access to the affordable and reliable energy needed to grow economically” and to back advancements that improve infrastructure and ultimately reduce emissions.
Environmental Protection Agency Administrator Scott Pruitt, Energy Secretary Rick Perry and President Donald Trump have all questioned the extent of humans’ contribution to climate change. The EPA’s website posted scientific conclusions similar to those in the new report until earlier this year, when Pruitt’s deputies ordered the pages removed.
The report comes as Trump and members of his Cabinet are working to promote U.S. fossil-fuel production and repeal several federal rules aimed at curbing the nation’s carbon output, including ones limiting greenhouse-gas emissions from existing power plants, oil and gas operations on federal land, and carbon emissions from cars and trucks. Trump has also announced he will exit the Paris climate agreement, under which the United States has pledged to cut its overall greenhouse-gas emissions between 26 percent and 28 percent compared with 2005 levels by 2025.
The report could have considerable legal and policy significance, providing new and stronger support for the EPA’s greenhouse-gas “endangerment finding” under the Clean Air Act, which lays the foundation for regulations on emissions.
“This is a federal government report whose contents completely undercut their policies, completely undercut the statements made by senior members of the administration,” said Phil Duffy, director of the Woods Hole Research Center.
The government is required to produce the national assessment every four years. This time, the report is split into two documents, one that lays out the fundamental science of climate change and the other that shows how the United States is being affected on a regional basis. Combined, the two documents total more than 2,000 pages.
The first document, called the Climate Science Special Report, is a finalized report, having been peer-reviewed by the National Academy of Sciences and vetted by experts across government agencies.
“I think this report is basically the most comprehensive climate science report in the world right now,” said Robert Kopp, a climate scientist at Rutgers who is an expert on sea-level rise and served as one of the report’s lead authors.
It affirms that the United States is already experiencing more extreme heat and rainfall events and more large wildfires in the West, that more than 25 coastal U.S. cities are already experiencing more flooding, and that seas could rise by between one and four feet by the year 2100. When it comes to rapidly escalating levels of greenhouse gases in the atmosphere, the report states, “there is no climate analog for this century at any time in at least the last 50 million years.”
Some members of the scientific community had speculated that the administration might refuse to publish the report or might alter its conclusions. During the George W. Bush administration, a senior official at the White House Council on Environmental Quality edited aspects of some government science reports.
Yet multiple experts, as well as some administration officials and federal scientists, said Trump political appointees did not change the special report’s scientific conclusions.
“I’m quite confident to say there has been no political interference in the scientific messages from this report,” David Fahey, an atmospheric scientist with the National Oceanic and Atmospheric Administration and a lead author of the study, told reporters on Friday. “Whatever fears we had weren’t realized. . . . This report says what the scientists want it to say.”
Perhaps no agency under Trump has tried to play down and undermine climate science more than the EPA. Political appointees recently instructed two agency scientists and one contractor not to speak as planned at a scientific conference. Pruitt has advocated for the creation of a government-wide “red team/blue team” exercise, in which a group of outside critics would challenge the validity of mainstream scientific conclusions around climate change.
The climate science report is already coming under fire from some of the administration’s allies.
The day before it was published, Steven Koonin, a New York University physicist who has met with Pruitt, preemptively criticized the document in the Wall Street Journal, writing that the report “ominously notes that while global sea level rose an average 0.05 inch a year during most of the 20th century, it has risen at about twice that rate since 1993. But it fails to mention that the rate fluctuated by comparable amounts several times during the 20th century.”
But one of the report’s authors suggested Koonin is creating a straw man. “The report does not state that the rate since 1993 is the fastest than during any comparable period since 1900 (though in my informal assessment it likely is), which is the non-statement Steve seems to be objecting to,” Kopp countered by email.
Still, the line of criticism could be amplified by conservatives in the coming days.
Joseph Bast, the chief executive of the Heartland Institute, a think tank that has long challenged many aspects of the science of global warming, also strongly critiqued the report in a statement to The Post on Friday.
“This is typical Obama-era political science,” Bast said. “It’s all been debunked so many times it’s not worth debating anymore. Why are we still wasting taxpayer dollars on green propaganda?”
The administration also released, in draft form, the second volume of the National Climate Assessment, which looks at regional impacts across the United States. This document is available for public comment and will begin a peer review process, with final publication expected in late 2018.
Already, however, it is possible to discern some of what it will conclude. A peer-reviewed EPA technical document released to inform the assessment finds climate change could exact a steep cost on the United States. That document, the Climate Change Impacts and Risk Analysis, finds that high temperatures could mean the nation may lose “almost 1.9 billion labor hours across the national workforce” by 2090, or $160 billion in annual lost income.
With high levels of warming, coastal property damage in 2090 could total $120 billion annually, and deaths from temperature extremes could reach 9,300 per year, or in monetized terms, $140 billion annually in damage. Additional tens of billions annually could occur in the form of damage to roads, rail lines and electrical infrastructure, the report finds.
This could all be lessened considerably, the report notes, if warming is held to lower levels.