Scientists move away from worst-case climate scenario as renewables surge

Climate scientists are increasingly moving away from one of the most pessimistic global warming scenarios, the RCP 8.5 pathway, which long projected a world 4.5‑5°C hotter by 2100. According to Norwegian broadcaster NRK, a recent study concluded that the scenario has become “increasingly improbable” due to declining renewable energy costs, stronger climate policies, and slower growth in global carbon dioxide emissions.

Emissions growth slows

“That’s because green technology has taken off very well. Emissions are still increasing, but now they are increasing by perhaps up to 1% a year, compared to 3‑4% a year, as they did in the early 2000s,” climate scientist Bjorn Samset told NRK. He noted that future climate projections depend heavily on assumptions about human behaviour and policy decisions. “Maybe climate policy works very well and we cut emissions very quickly. Maybe climate policy doesn’t work at all, there will be many big wars and the like. Then there will be very high emissions.”

Middle scenarios gain relevance

According to Samset, RCP 8.5 is unlikely to play a major role in the next IPCC assessment report. “Green technology has taken off very well … In that sense, the world is definitely doing well. It is a positive sign that it is now more relevant to think about the middle scenarios.” However, scientists also warn that uncertainty remains regarding the climate system’s sensitivity to emissions.