World could warm 3.25C by 2100 under current policies, Swiss-German study suggests

Global temperatures could rise by around 3.25C (5.85F) by the end of the century under current policies, making Switzerland's most severe official climate scenario increasingly likely, according to research from Switzerland and Germany.

The study, conducted by researchers at ETH Zurich and Leipzig University suggests that previous climate projections may have underestimated future warming, Swissinfo reported Tuesday.

"For any emission trajectory without immediate and drastic emission cuts, we expect warming to be 25% higher," said Gergana Gyuleva, a doctoral researcher at ETH Zurich and lead author of the study.

"What happens in a 3C (5.4F) world isn't changed by our results. Our results only change how soon or how likely this 3C world becomes," she said.

The findings have particular implications for Switzerland, which is warming faster than the global average. A world that is 3C warmer than pre-industrial levels would translate into roughly 4.9C (8.82F) of warming in Switzerland.

The country's hottest summer on record offered a glimpse of such conditions. Basel recorded 58 days above 30C (86.5F), compared with 41 in 2003; Bern had 46 compared with 29, while Zurich had 38 compared with 27.

The scenarios published by MeteoSwiss and ETH Zurich last November project about 30 days with temperatures above 30C for the Zurich area in a typical summer under a 3C warming scenario.

Researchers revised their projections by accounting for natural climate variability and satellite measurements of Earth's energy imbalance — the difference between incoming solar energy and heat radiated back into space.

The study also estimates that the remaining global carbon budget is around one-fifth smaller than previous models suggested.

"Our results point to the need for faster mitigation for a given temperature target," Gyuleva said.

Researchers stressed that the higher warming scenario is not inevitable, saying that severe emissions reductions could substantially limit future warming.