With scientists divided between hope and despair, a new study finds that the model projecting warming of 4.3 degrees Celsius is “actually the best choice.”

A piece of the Perito Moreno glacier, part of the Southern Patagonian Ice Field, breaks off and crashes into lake Argentina in the Los Glaciares National Park on April 5, 2019 in Santa Cruz province, Argentina. Credit: David Silverman/Getty Images

A piece of the Perito Moreno glacier, part of the Southern Patagonian Ice Field, breaks off and crashes into lake Argentina in the Los Glaciares National Park on April 5, 2019 in Santa Cruz province, Argentina. Credit: David Silverman/Getty Images

When scientists in the early 2000s developed a set of standardized scenarios to show how accumulating greenhouse gas concentrations in the atmosphere will affect the climate, they were trying to create a framework for understanding how human decisions will affect the trajectory of global warming.

The scenarios help define the possible effects on climate change—how we can limit the worst impacts by curbing greenhouse gas emissions quickly, or suffer the horrific outcome of unchecked fossil fuel burning.