99.9 percent of climate change man-made – knowledge

When SPD Chancellor candidate Olaf Scholz commented on climate change during the election campaign, he always added an adjective: “man-made”. As if we still had to point out in 2021 that humans are the main cause of climate change – that the burning of coal, oil and gas is driving the global greenhouse effect. “It is clear that human influence has warmed the atmosphere, ocean and land,” it says more clearly than ever before new IPCC assessment report.

Of course, this assessment is not entirely new: in 2013, there was already one that received a lot of attention Meta-studythat 97 percent of all scientific work on climate change between 1991 and 2012 supported the statement that climate change was man-made. The remaining three percent gave other, contradicting reasons, such as supposedly stronger sun activity or volcanism. Nonetheless, energy companies like Exxon Mobil and conservative think tanks have long tried to portray climate science as divided in order to prevent political measures that could threaten their business model in the long term.

Mark Lynas of the Alliance for Science at Cornell University in Ithaca, New York State, wanted to know if anything in the consensus of climate science had changed since then. To do this, he and two colleagues evaluated more than 88,000 scientific studies on climate change that had been published between 2012 and November 2020. First with a random sample, then with the help of an algorithm that searched the entire data set for keywords that are typically used by climate skeptics, including “cosmic rays”, “solar” and “natural cycles”.

The result is now in the specialist journal Environmental Research Letters published: Only 28 papers more or less explicitly doubted that climate change is man-made. So less than a per mille. These had been published in relatively insignificant journals. “That should have been pretty much the last word,” says Lynas.

Opponents of an energy transition would now be pursuing a completely different tactic anyway, argues the well-known US climate scientist Michael Mann from Pennsylvania State University. Since it now seems unpromising to deny climate change and the leading role of humans in it, they would instead work to delay or prevent political measures – for example by redirecting the political debate. For example, with the message that climate change cannot be solved with political measures, but only if each individual checks his or her individual lifestyle. That, in turn, was heard from time to time in the German election campaign.

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