The first climate tipping points can be achieved by 2030.

A farmer from Brandenburg drives through his dry field. It hasn’t rained for weeks. Photo: Patrick Pleul / dpa

By 2030, four global climate tipping points can be reached. This is the result of an analysis by an international group of climate researchers. Two of these tipping points are related to the Greenland ice sheet and the West Antarctic ice sheet, respectively.

Exceeding the threshold could lead to dynamics that would allow the ice caps to melt further, even if the temperature on Earth does not rise further, reports a team led by David Armstrong McKay and Timothy Lenton at the University of Exeter (UK). the journal “Science”.

Lenton is one of the first researchers to identify global climate tipping points in 2008. They defined tipping points as “the critical threshold at which a minor disturbance can qualitatively change the state or evolution of a system.” For example, when a melting glacier loses height, its surface shifts into lower, warmer air layers, which accelerates the melting. Beyond the tipping point, feedback processes can ensure development becomes unstoppable. In the case of ocean currents such as the Gulf Stream, changes can have a huge impact on the climate.

Four points of heel at an angle of 1.5 degrees

Since 2008, more than 200 studies on “tipping points” have been published. Armstrong McKay, Lenton and colleagues carefully studied them and based them on an updated model of climate turning points. They identified nine tipping points relevant to the global climate and seven tipping points that have far-reaching regional effects. Scientists estimate that when global warming reaches an average of 1.5 degrees Celsius compared to the pre-industrial era, it will hit four tipping points: the Greenland and West Antarctic ice sheets, tropical coral reef dieback and permafrost thawing.

Based on the events of recent years, they predict that 1.5 degrees will become reality as early as 2030. If all the actions currently planned by politicians were implemented, global temperature could be limited to an increase of 1.95 degrees by 2100. However, the measures taken so far would limit the warming to only 2.6 degrees. Johan Rockström of the Potsdam Institute for Climate Impact Research said that “the earth is on track to exceed several dangerous threshold values ​​that would have catastrophic consequences for people worldwide.” Rockström is another co-author of the study.

More warming, more tipping points

As global warming approaches two degrees, further tipping points become possible: melting mountain glaciers beyond the polar regions and dying of boreal coniferous forests in the southern distribution area. However, changes to the Gulf Stream, which is part of the Atlantic overturning circulation and which ensures mild temperatures in Europe, are of particular importance for Europe: scientists believe that the Gulf Stream branch south of Greenland is becoming more and more likely to collapse. which will also affect the entire overturned cycle. However, it is likely that the entire Atlantic circulation – and with it the Gulf Stream – could collapse if global temperature rises by more than four degrees.

For ice sheets, too, scientists assume the process takes 2,000 years (West Antarctic Ice) or 10,000 years (Greenland Ice) to melt completely. In other parts of Antarctica, tipping points could only be achieved with global warming of three to seven degrees. However, if all the polar ice caps were to melt, global sea levels would rise by about 66 meters. Other consequences of climate change can also have catastrophic consequences for life on Earth. That is why Rockström cautions: “To maintain good living conditions on Earth, to protect people from rising extremes, and to enable stable societies, we must do everything in our power to prevent tipping points from being exceeded – every tenth of a degree counts.”

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