This week, the United Nations' top climate science panel is gathered in South Korea to prepare a new report for policymakers, answering major questions about the future of climate: What will 1.5 degrees Celsius of warming do to the planet? And what are the chances that such an increase can still be avoided?
An early draft of the Intergovernmental Panel on Climate Change's 2018 report, leaked to Climate Home News, found that, without drastic and immediate action, temperatures could rise more than 1.5 degrees Celsius above pre-industrial levels before mid-century. In other words, the globe is on track to miss the most ambitious target of the Paris Agreement, which calls on nations to take actions to keep global warming below two degrees and as close to 1.5 degrees as possible.
The 1.5-degree goal was included in the Paris Agreement to appease low-lying islands and other vulnerable nations expected to bear the brunt of climate change's harshest effects. In 2015, when 195 countries joined the accord, limiting warming below 2 degrees seemed a more achievable goal—and one that seemed adequate, at least to protect higher-lying nations or richer countries in the global north. But in the few short years since then, a number of costly and destructive weather events—made more extreme by climate change—have raised concerns that even a half degree more could be too much.
In the wake of the Paris Agreement, governments commissioned the IPCC to prepare a special report on the impacts of a 1.5-degree increase in global temperatures above pre-industrial levels. Dozens of climate scientists from around the globe reviewed thousands of research papers on the impacts, costs, and likelihood of staying below 1.5 degrees, and distilled that research in a 15-page report for policymakers. In South Korea, scientists and representatives from more than 130 countries have been going over the document line-by-line to ensure that both the research community that produced it and the governments that will have to incorporate its findings into policy are in agreement on the text.
The IPCC's process of carrying out an extensive literature review and incorporating comments from outside experts and governments has given the panel a reputation for producing sound, but conservative, climate reports—which is why the draft's findings that the world could break the 1.5-degree threshold by 2040 are all the more concerning. While the first draft report said there was a "very high risk" warming would exceed 1.5 degrees, a later leaked draft was more optimistic.
The report, which is due out on Monday, will no doubt be politically charged—it's the first IPCC report released since President Donald Trump announced his intention to pull the United States out of the Paris agreement—and environmental groups will be carefully watching how it is received. India's Business Standard reported this week that the U.S. delegation in Korea requested more than 100 "dilutions, alterations and deletions" in the text of the report.
"The time is up. We are on the edge and the climate impacts that scientists warned us about decades ago are here. This is our new reality," Jennifer Morgan, executive director for Greenpeace International, said in a statement this week. "But there is hope. This IPCC report will make clear the choices and the trade-offs. For decision makers around the world, it is now their responsibility to listen and step up with real climate leadership."
Parties to the Paris accords already knew that the pledges as they currently stand would not be enough to keep warming below two degrees. That's why the agreement itself includes a mechanism for countries to increase ambition over time. The new report will inform the process of revving up climate action.
So far, progress has been incremental, but to keep warming below 1.5 degrees would require a rapid and extensive transformation—an end to gas-powered vehicles and coal-fired power plants, a proliferation of technologies to suck carbon out of the atmosphere—to achieve net zero emissions by mid-century.
But without action, climate change will also drastically reshape our lives and environments. Already, the one-degree rise in global temperatures since the industrial revolution has led to sea-level rise, droughts, and extreme weather events, which are only expected to become more frequent and severe as warming continues.
"The decisions we make now about whether we let 1.5 or 2 degrees or more happen will change the world enormously," Heleen de Coninck, a lead author on the IPCC report, told the BBC. "Lives of people will never be the same again either way, but we can influence which future we end up with."