All of the plausible scenarios the Intergovernmental Panel on Climate Change (IPCC) is currently using predict less than 3 °C in total warming by 2100, according to a new study published in Environmental Research Letters.
The study found that out of the IPCC’s original 1,311 scenarios, only 71 (about 6%) remained plausible in 2022. When using near-term projections from 2005 to 2050, less than half of that – only 35 – of the IPCC scenarios are still plausible.
According to the study, the median projection for warming by 2100 is 2.2 °C.
While the 2.2 °C projection is slightly above the Paris Agreement’s goal of less than 2 °C by 2100, the findings are still good news for the future of climate change. The most commonly used scenario for climate research – which is referred to as “business as usual” – projects potentially more than 5 °C by 2100, and has been used as a basis for climate research despite its implausibility.
Further, the 2021 IPCC report states that under current policies climate change is falling “in line” with intermediate scenarios that estimate warming of 2.7 °C by 2100, which is still far higher than the 2.2 °C projection.
As noted by Dr. Roger Pielke Jr., one of the authors of the study, the IPCC has “actually never evaluated for plausibility its family of scenarios, nor its subset of 11 used for research. In fact, it is 2022 and the IPCC still doesn’t evaluate its scenarios for plausibility. Of course, in 2022 there are more and different possible futures than were envisioned decades ago, so we need to update our scenarios. In fact, keeping scenarios updated should be a continuous process, lest a gap open up between what is plausible and what we are studying and using to guide policy.”
“Unfortunately, many people’s view of climate continues to be shaped by implausible futures developed as scenarios many years and even decades ago. Reality is quite different,” Pielke added, then pointed to the study which said, “Our analysis suggests that the world thus sits in an enviable position to take on the challenge of deep decarbonization, at least as compared to where IPCC baseline scenarios and some of the public discourse projected the world to be in 2021.”