The tightening of the climate target in the Paris Agreement (to significantly below 2°C and preferably to 1,5°C) could paradoxically weaken the efforts in climate politics. The 1,5°C-goal will most likely only succeed with a temporary exceedance of this benchmark. Only by combining aggressive reduction of emissions and extensive extraction of CO2 from the atmosphere, the temperature might fall below this agreed benchmark decades later.

The almost inevitable rise of temperature above 1,5°C could make the calculated “overshoot” the norm and hereby make it generally acceptable. Then again, this could lead to an undesirable political “flexibilisation” of climate protection. If temperature goals are not perceived as absolute limits, one cannot fail them anymore, no matter what future successes will be made in the reduction of emissions worldwide. Therefore, clear restrictions are crucial for achieving temperature goals. Especially the extent, the duration and the termination of exceedance of benchmarks must be determined. Only in this way, an evaluation of the political promises to reverse the negative trend and to stabilize the temperature below the target level can take place. Otherwise, there will be a lack of political liability resulting in the threat of an increasing arbitrariness in climate politics.

Prof. Löschel’s comment in Nature Geoscience is available here.

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