Humans a key threat to climate: U.S. study
WASHINGTON • The Trump administration released a dire scientific report Friday detailing the growing threats of climate change. The report stands in stark contrast to the administration’s efforts to downplay humans’ role in global warming, withdraw from an international climate accord and reverse Obama-era policies aimed at curbing America’s greenhouse-gas output.
The White House did not seek to prevent the release of the government’s National Climate Assessment, which is mandated by law, despite the fact that its findings sharply contradict its policies.
The report affirms that climate change is driven almost entirely by human action, warns of potential sea level rise as high as nearly 2.5 metres by the year 2100, and enumerates myriad climaterelated damages across the United States that are already occurring due to 1 degree 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 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, continues to grind on even as top administration officials have minimized or disparaged its findings.
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 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 federal rules aimed at curbing 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 U.S. has pledged to cut its overall greenhouse-gas emissions between 26 per cent and 28 per cent compared to 2005 levels by 2025.
The report could have considerable legal and policy significance, as the scientific matter provides new and stronger support for 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, the director of the Woods Hole Research Center.
Two documents were released. The first, 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.
“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 one of the report’s lead authors.
It affirms that the U.S. is already experiencing more extreme heat and rainfall events and more large wildfires in the West, that more than 25 U.S. coastal cities are already experiencing more flooding, and that seas could rise by between 0.3 and 1.3 metres by 2100, and perhaps even more than that if Antarctica proves to be unstable, as is currently feared.
When it comes to rapidly escalating levels of greenhouse gases, the report states, “there is no climate analog for this century at any time in at least the last 50 million years.” Given these strong statements — and how they contradict Trump administration policies — some members of the scientific community had speculated that the administration might refuse to publish the report or alter its conclusions. Yet multiple experts, as well as some administration officials, said Trump political appointees did not change the special report’s scientific conclusions.