Thursday, 21 July 2022

"No one has any data that suggests two degrees of warming is dangerous for humanity or the environment."

"Germany’s past Environment Minister, Norbert Röttgen, said in 2009 that if the two-degree limit were exceeded, 'life on our planet, as we know it today, would no longer be possible.'
    "'Der Spiegel' calls this scientific nonsense. They claim that the father of the two-degree limit was Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research (PIK). Schellnhuber tells them that he estimated average global temperatures since the rise of Homo sapiens and decided from proxy data that over the past 130,000 years global average surface temperatures were never more than two degrees higher than before the beginning of the industrial revolution. This became the two-degree limit proposed by the European Council of environment ministers in 1996. The limit is arbitrary and speculative, and contradicted, at least in the Northern Hemisphere, by the data we show [here]. Currently Schellnhuber admits that keeping global warming below two degrees is not feasible. He shows no data that suggests 2° of warming is dangerous, he just attempts to show it is unusual....
    "How does he know that the global average surface temperature did not exceed two degrees Celsius? The short answer is, he doesn’t. Estimating global average surface temperature before 1900 is speculative, and before 1850, virtually impossible, there just isn’t enough good data.
    "Yale Professor and Nobel Prize winner [in economics] William Nordhaus probably first suggested the two-degree limit in 1977. Nordhaus uses the same logic that Schellnhuber used. He speculates that the maximum global surface temperature over the past 100,000 years was two degrees higher than in the late 19th century, so we should not exceed that. The problem is neither Nordhaus nor Schellnhuber know how much global surface temperatures have varied before 1850, and no one else does either. No one has any data that suggests two degrees of warming is dangerous for humanity or the environment."
~ Andy May, from his article 'Is the Two Degree Limit Meaningful?' [emphasis added]


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