Washington
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 potential sea-level 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 1.8 degrees Fahrenheit of global warming 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 states. “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 downplay 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. “In the United States, energy related carbon dioxide emissions have been declining, are expected to remain flat through 2040, and will also continue to decline as a share of world emissions.”
Shah added that the Trump administration “supports rigorous scientific analysis and debate.” He said it 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. One of the EPA’s web pages posted scientific conclusions similar to those in the new report until earlier this year, when Pruitt’s deputies ordered it 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 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 now a finalized report, having been peer-reviewed by the National Academy of Sciences and vetted by experts across government agencies. It was formally unveiled Friday.
“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 1 and 4 feet by the year 2100, and perhaps even more than that if Antarctica proves to be unstable, as is feared. The report says that a rise of over eight feet is “physically possible” with high levels of greenhouse-gas emissions but that there’s no way right now to predict how likely it is to happen.
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 that Trump political appointees did not change the special report’s scientific conclusions. While some edits have been made to its final version — for instance, omitting or softening some references to the Paris climate agreement — those were focused on policy.
“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.”