Scientists have narrowed the range for future global heating, and both the best and worst-case scenarios are less likely than we thought
A recent study published in Reviews of Geophysics found that both the best and worst-case scenarios of global heating caused by CO2 emissions are less likely than scientists had previously believed.
For decades, the United Nations has set the most probable climate sensitivity window (i.e. the range of potential temperature change) to be between 1.5 and 4.5 C. However, the new data narrows that range to between 2.6 and 3.9 C.
In other words: Global temperatures will likely not rise as much as we thought they might, but on the other hand, we will not be able to keep them as low as we thought we could.
While this reduces the uncertainty over climate outcomes, the researchers emphasized that it is still crucial to dramatically reduce CO2 emissions. Although global heating is unlikely to exceed 4.5 C, the optimistic end of the spectrum—heating below 1.5 C—is almost impossible. Thus, unless there is a drastic reduction in CO2 emissions, catastrophic warming is inevitable.
These warming effects are closer than we may think. This year has seen record-breaking heat waves, from a scorching summer in the U.S. to temperatures as high as 100.4 degrees Fahrenheit in the usually frigid Arctic Circle.
However, the study’s lead author Zeke Hausfather, while maintaining that the time is now for the world to take drastic action against climate change, has something positive to say: “This is moderately good news,” he told The Guardian. “It reduces the likelihood of some of the catastrophically high estimates. If we were planning for the worst, the worst has become less likely.”