Failure of the "district heating of Europe" threatens

Risk of breaking off the Atlantic Ocean circulation later this century

Near-surface circulation in a high-resolution model of the IFM-GEOMAR. The colors symbolize the strength of the current. © IFM-GEOMAR
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The "Europe's heating system" could be irrevocably programmed to "off" in this century. Leading climatologists believe that parts of the Atlantic ocean circulation that is so important to the climate of Europe, and not just Europe, could fail as soon as the temperature rises by two degrees.

The so-called Thermohaline Circulation (THC) transports large quantities of heat into the North Atlantic, thereby contributing significantly to the relatively mild European climate. A demolition of the current would have a whole series of dramatic effects: the sea level would rise rapidly by up to a meter in the North Atlantic, the marine ecosystem would be massively disturbed and the global precipitation distribution changed. "Such a dramatic global flow change would disrupt our entire climate system, " says Anders Levermann, physicist at PIK and co-author of the study.

Now published in the journal "Climatic Change", the study is based on extensive interviews with leading climate scientists in the field of Atlantic ocean dynamics, conducted by researchers from the Potsdam Institute for Climate Impact Research (PIK) and Carnegie Mellon University in Pittsburgh, USA.

Failure already possible from two degrees warming

Even with a further global warming from 2 ° C to the year 2100, the majority of the experts surveyed believe that a termination of the THC by the end of the century can not be reversed. For a warming of 4 ° C - a probable result of uninterrupted greenhouse gas emissions, according to the latest UN climate report - two-thirds of scientists assume between 10% and 60% of probabilities. "Given the potential consequences, this risk is too high to be ignored, " says Kirsten Zickfeld, head of the study.

The probabilities given in the survey are much larger than those resulting from the latest model simulations. "The advantage of expert interviewing over traditional model studies is that the estimates are based on the researchers' collective knowledge. This includes observation data, understanding the climate history of our planet as well as the individual assessment of the capabilities and weaknesses of the models, "says Zickfeld. display

The collapse of the Atlantic ocean circulation is just one of many possible so-called tilt processes in the climate system. These are phenomena that can occur abruptly or irreversibly as a result of creeping global warming and have far-reaching implications. Other tipping processes include the melting of Arctic sea ice as well as the greenland melt or rapid changes of the Indian monsoon.

(Potsdam Institute for Climate Impact Research, 02.07.2007 - NPO)