Climate tipping points can be reached by 2030

The team led by David Armstrong McKay and Timothy Lenton of the University of Exeter (Great Britain) reported this in the journal Science. Lenton is one of the researchers who first identified tipping points for global climate in 2008. They defined tipping points as “a critical threshold at which a small disturbance can qualitatively change the state or evolution of a system”. For example, when a glacier loses height as it melts, its surface moves to lower, warmer layers of air, speeding up the melting.

Tipping points with far-reaching regional implications
Beyond the tipping point, feedback processes can ensure that development is unstoppable. In the case of ocean currents such as the Gulf Stream, changes can have a huge impact on the climate. More than 200 studies on the topic of “tipping points” have been published since 2008. McKay, Lenton and colleagues studied them carefully and based them on an updated model of climate tipping points. They identify nine tipping points that are relevant to the global climate and seven tipping points that have a broad regional impact.

The researchers estimate that when global warming reaches an average of 1.5 degrees Celsius compared to the pre-industrial era, four tipping points will be reached: the Greenland and West Antarctic ice sheets, the dying of tropical coral reefs and the thawing of the permafrost.

Based on developments in recent years, they predict that 1.5 degrees will already become a reality in 2030. If all the measures now planned by politicians are implemented, the global temperature could be limited to 1.95 degrees by 2100. However, the measures introduced so far would limit warming to only 2.6 degrees. Johan Rockström of the Potsdam Institute for Climate Impact Research is quoted in a statement from his institute – Rockström is another co-author – that Earth is well on track to cross several dangerous thresholds that would have catastrophic consequences for people around the world. world study.

Gulf Stream changes relevant to Europe
As global warming approaches two degrees, further tipping points become possible: the melting of mountain glaciers outside the polar regions and the death of boreal coniferous forest in the southern range. However, the changes in the Gulf Stream, which is part of the Atlantic circulation and provides mild temperatures in Europe, are particularly relevant for Europe: the researchers say a collapse of a Gulf Stream branch south of Greenland, also affecting the entire Gulf Stream, is becoming increasingly likely. will affect reversing circulation.

However, it is only likely that the entire Atlantic circulation – and with it the Gulf Stream – could collapse if the global temperature rises by more than four degrees. The researchers also assume a process of 2000 years (West Antarctic ice sheet) or 10,000 years (Greenland ice sheet) for the ice sheets until they melt completely. In other parts of Antarctica, the tipping points would not be reached until global warming of three to seven degrees. However, if all the polar ice caps melted, global sea levels would rise by about 66 meters.

“Must avoid overrun”
Other impacts of climate change could also have catastrophic consequences for life on Earth. Rockström therefore warns: “To maintain good living conditions on Earth, protect people from increasing extremes and enable stable societies, we must do everything we can to avoid crossing tipping points – every tenth degree counts.”