The president wants to limit the scope of federal climate assessments, which will leave policymakers and the public unprepared to deal with the consequences of climate change.

Since taking office in 2017, President Donald Trump has dramatically reshaped the nation's climate policies, rolling back dozens of environmental protections and regulations put in place by his predecessors to reduce emissions and prevent catastrophic climate change. Now his administration is taking aim at climate science itself: The New York Times reported this week that the White House plans to change the methodology some United States agencies use to predict the future climate—including, among other things, eliminating worst-case climate projections from government reports such as the National Climate Assessment.

Sometimes called "business as usual" projections, the worst-case climate scenarios provide a view of what the climate could look like decades from now if the U.S. continues emitting at its current levels.

Kelly Levin, a senior associate at the non-profit World Resources Institute, called the move a "new line of attack" for an administration that quickly established itself as hostile to science and climate action. "Since the beginning of the administration, we've seen science and really truth at large under siege all around us," she says.

Since the inauguration, Trump has stacked his administration with vocal climate skeptics, slashed funding for basic research, limited the types of scientific studies that can inform policy, and tried to bury the fourth National Climate Assessment by releasing the report on the day after Thanksgiving—a strategy that backfired, according to Andrew Light, a distinguished senior fellow at WRI and a former senior adviser on climate change to the U.S. Department of State. The 1,600-page report showed that, unless the U.S. steeply curbs emissions, rising temperatures could lead to more deadly heat waves, disease outbreaks, and powerful storms that cost taxpayers hundreds of billions of dollars every year by the end of the century.

"I think that it's safe to say that it was one of the biggest climate news days in U.S. American history," Light said on a press call Wednesday morning.

"What the fourth National Climate Assessment report made clear is that unabated climate change is going to substantially damage America's communities and economy and environment," Levin says. "It painted a picture of the economy on track to lose hundreds of billions of dollars annually by the end of the century."

The Trump administration officials tried to downplay the findings by claiming that the report placed too much weight on the worst-case climate scenario. "The irony is the Trump administration is really doing everything in its power to lead us down the path of the worst-case scenario," Levin says, "in terms of rolling back so many key climate policy decisions."

The Trump-appointed head of the U.S. Geological Survey has also directed staff to use climate models that only project impacts out until 2040—despite the fact that climate scientists agree that the largest impacts of global warming will emerge in the second half of the century.

Limiting the scope of the government's scientific assessments will leave policymakers and the public ill-equipped to deal with the consequences of climate change; we can't prepare for future risks that we don't see coming. "We need to have a good understanding of how our actions today are going to have implications for the decades in front of us, and the largest divergence of impact is going to be in the second half of the century," Levin says. "So if you cut off projections in 2040, you really are keeping the public as well as decision-makers in the dark."

"They well know that if we fail to act to bring down our carbon emissions over the next decade, this will lock in disastrous melting of the ice sheets, sea level rise, and a rise in devastating weather extremes decades down the road," says Michael Mann, a climate scientist at Penn State University. "They don't want people to look down the road. They want to inflict a collective societal myopia that benefits their fossil fuel industry friends at the expense of us, our children, grandchildren and future generations."

More than a dozen federal agencies and departments contribute to the National Climate Assessment, and while the U.S.G.S. may be embracing the White House's guidance, not every agency involved plans to change scope of the models it uses to project climate change for its individual reports. The National Oceanic and Atmospheric Administration, for example, told the Times it had no planned changes at this time. Researchers can also continue to publish long-term climate projections in peer-reviewed journals, which form the basis for the national assessment, according to Levin. "Universities, research organizations, scientific journals, and the media will need to double down to ensure that findings are accessible to the American people," she says.

"The administration is trying to keep the U.S. really mired in our past and unprepared for the future," Levin says. "But, you know, at the end of the day, facts are really going to be the final arbiter of what happens to climate and society. The climate isn't going to act differently because some individuals in the White House don't believe in the scientific consensus."

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