Researchers say "business as usual" could actually put planet on track for 4.78°C to 7.36°C rise by 2100
By Nadia Prupis, Common Dreams
Greenhouse gases are rising so fast that it could soon be "game over" for the climate, a leading scientist warned in response to a new study published Wednesday that finds the planet could be heading for more than 7°C warming within a lifetime.
The study, published in the journal Science Advances, reported that the United Nations' most accurate estimates on the "business as usual" rate of global warming may actually be vastly underestimated.
The U.N.'s Intergovernmental Panel on Climate Change (IPCC) recently estimated that continuing to use fossil fuels at current rates would put the Earth on track for an average temperature rise of 2.6°C to 4.8°C above pre-industrial levels by 2100.
But the authors, a team of climate researchers and scientists at the University of Hawaii at Manoa, the University of Washington, the University of Albany, and the Potsdam Institute for Climate Impact Research, say the range for that same time period is actually 4.78°C to 7.36°C. That's because the climate has "substantially higher sensitivity" to greenhouse gases during warm phases, they write—which ultimately means that "within the 21st century, global mean temperatures will very likely exceed maximum levels reconstructed for the last 784,000 years."
The results correspond with other recent data that finds, despite all the pledges made in the landmark Paris climate agreement, the planet is still on track for at least a 3°C global temperature rise. Scientists have long warned that catastrophic, irreversible damage would come at 2°C.
President-elect Donald Trump, who has denied that climate change exists, has vowed to withdraw from the Paris agreement, and his transition team is rife with fellow deniers and fossil fuel industry lobbyists. Green groups on Wednesday reacted to his win by calling on people around the world to mobilize against his anti-environmental policies "for the sake of our brothers and sisters around the world and for all future generations."
Professor Michael Mann of Penn State University told the Independent that the study "does indeed provide support for the notion that a Donald Trump presidency could be game over for the climate."
"By 'game over for the climate,' I mean game over for stabilizing warming below dangerous (i.e. greater than 2°C) levels," he wrote in an email to the outlet. "If Trump makes good on his promises, and the U.S. pulls out of the Paris [climate] treaty, it is difficult to see a path forward to keeping warming below those levels."
Dr. Tobias Friedrich, one of the authors, said, "Our results imply that the Earth's sensitivity to variations in atmospheric carbon dioxide increases as the climate warms. Currently, our planet is in a warm phase—an interglacial period—and the associated increased climate sensitivity needs to be taken into account for future projections of warming induced by human activities."
"The only way out is to reduce greenhouse gas emissions as soon as possible," he said.