In a May 16 Truth Social post, President Donald Trump cited updated climate change scenarios to misleadingly claim that experts had “admitted” prior climate change projections “were WRONG! WRONG! WRONG!” The regularly scheduled revision reflects in part the progress the world has made on moving away from fossil fuels.
Trump was reacting to a new set of seven scenarios of emissions by the end of the century, proposed in an April 7 paper by an international group of scientists. Over time, the range of plausible scenarios has narrowed . The most pessimistic scenario now shows lower emissions than 15 years ago, when the prior scenarios were developed, and the most optimistic one now shows more.
Trump, however, used the update to cast doubt on the reality and seriousness of global warming. “GOOD RIDDANCE!” he wrote . “After 15 years of Dumocrats promising that ‘Climate Change’ is going to destroy the Planet, the United Nations TOP Climate Committee just admitted that its own projections (RCP8.5) were WRONG! WRONG! WRONG!”
RCP8.5 was the most pessimistic of four scenarios that were selected in 2007 and described in 2011. The scenarios looked at how much the climate might change by 2100, relative to the industrial revolution.
“RCP8.5 was always this low-probability, high-impact case,” Detlef van Vuuren , a climate researcher at Utrecht University and PBL Netherlands Environmental Assessment Agency, told us. He helped lead the effort to develop both the new and earlier climate scenarios. As 15 years have passed and the end of the century has gotten closer, it has become clearer what emissions paths are most plausible.
It’s “useful to consider possible outcomes that are less attractive, and it doesn’t mean that you were wrong by considering those if they didn’t come true,” van Vuuren said. “Unfortunately, the overall outcome of all of this is that we are in a situation that is actually leading to quite strong climate impact still.”
Van Vuuren also clarified that Trump is incorrect to call the international group of researchers behind the scenarios “the United Nations TOP Climate Committee.” A U.N. group, the Intergovernmental Panel on Climate Change , summarizes the existing research on climate change. The scenarios are anticipated to have a “major role” in the group’s next climate assessments, he said, but it did not come up with the new scenarios.
“The paper belongs to the broader body of scientific literature produced by the international research community, under the coordination of the World Climate Research Program, not the IPCC,” the IPCC wrote in a May 20 statement.
We asked the White House if Trump was referring to the IPCC in his post and if he was suggesting that climate change is not a serious problem. In an emailed reply, White House spokeswoman Taylor Rogers said that “Dumocrats” and others had for years made “bogus ‘climate change’ claims that we would destroy the planet,” leading countries that pursued energy transition policies to be “destroyed” with “blackouts and sky-high prices.”
“The rogue climate activists continue to be ‘Wrong! Wrong! Wrong!’ and President Trump continues to be ‘Right! Right! Right!’” Rogers said.
Why Climate Scenarios Have Narrowed
Experts said that Trump’s comments on climate scenarios misrepresented their purpose.
“Scenarios are not predictions: they are ‘what-if’ pictures of the future,” Katharine Hayhoe , a climate scientist and professor at Texas Tech University, told us via email.
“The highest-emission scenario serves as a basis for exploring the potential consequences of climate change if everything goes wrong,” a post on the new climate scenarios from the PBL Netherlands Environmental Assessment Agency, a Dutch government research institute, explained. “After all, it is important to ensure that we are also prepared for undesirable developments.”
Termed “representative climate pathways,” the older scenarios by design covered a broad range of climate trajectories, with RCP8.5 representing the 90th percentile of baseline scenarios in the literature at the time. (A baseline scenario illustrates a case where people do not take action to mitigate climate change, but there can be a range of baseline scenarios depending on other factors, such as how much fossil fuel use increases.) The most optimistic scenario, by contrast, represented below the 10th percentile of mitigation scenarios in the literature.
Van Vuuren likened the scenarios to a range of possible times a person might arrive at a destination on a drive. Initially, a person might want to consider the possibility of a traffic jam or other misadventures. But as the trip progresses, a traffic jam will or will not emerge, and the range of plausible arrival times will become narrower. In the case of the climate scenarios, the destination is the year 2100, and we are now 15 years closer to it than we were when the previous scenarios were laid out.
Wind turbines and a levee in the Netherlands. Photo by Sjo…
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