Dave Levitan
When the countries of the world signed the Paris Agreement in 2015, their ambitious goal of keeping warming to 1.5 degrees Celsius above pre-industrial levels was considered difficult, but achievable. Three years later, the Intergovernmental Panel on Climate Change’s report on the 1.5-degree target made the challenge more plain, warning that there were only about 12 years for the world to get its act together enough to meet the mark.
Five of those years are now gone, and today 1.5 degrees is looming large on the horizon. In July, new head of the IPCC Jim Skea said it is “absolutely for sure” that current government policies won’t come close to preventing it. Emissions, which need to be falling rapidly on the way toward net-zero at mid-century, stubbornly continue to rise. The odds of some massive shift in global fortunes within this decade seem slim. Enter the Overshoot Commission.
Overshoot refers to the idea that even on the way to a low-carbon economy and stabilization of global temperatures, we may push past 1.5 degrees —or the higher 2.0 degree target also set out in the Paris Agreement— before, hopefully, starting to head back down. The Overshoot Commission, composed of 12 commissioners from around the world, including former heads of state, wants the world to talk about how to avoid or manage that scenario. The commission released its first report on Thursday.
“It's an important discussion because the more we delay action on global warming, the higher the probability is that we do pass 1.5 and even the ‘well below two [degrees]’ standard,” said Chris Field, a professor and director of the Stanford University Woods Institute for the Environment, who also served as one of several science advisors to the commission. “It's not to say that anybody is supportive of decreasing efforts to meet the goals of the Paris Agreement, but just to recognize that the trajectory we're on doesn't inspire any level of confidence that we will.”
Impacts of 1.5 degree overshoot
A time period when the world has missed its climate goals, but is theoretically going to get there, would be a dangerous one. “Recent history has shown us a lot about what happens with each increment of warming,” Field told The Messenger. “Increasingly, we've seen heatwaves that just shattered records, and heavy precipitation events that are way outside the realm of historical experience. And that's what we'll see more of in the future.”
The report’s section on the impacts of overshoot reads like a horror story. “Areas currently on the margins of human habitability may become uninhabitable,” the authors wrote. “Ecosystems currently experiencing heat stress may not survive in their present form.” Human health would be severely at risk, marine ecosystems would collapse, extreme precipitation events would become commonplace.
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