Studie visar att klimatkänsligheten kan vara högre än man tidigare trott. En svårighet är att fastställa vilken nettoeffekt molnen kommer att ha. Nu visar studier att 5 C kan vara sannolikt och veteraner inom forskningen häpnar själva.
Det här är väldigt dåliga nyheter. Men i brist på bättre kunskap måste vi ta detta på allvar, menar man och säger att det krävs mer forskning kring detta.
Men vi kan naturligtvis inte vänta på detta. Vi måste stoppa utsläppen av CO2 så fort som möjligt!
Climate worst-case scenarios may not go far enough, cloud data shows
Modelling suggests climate is considerably more sensitive to carbon emissions than thought
Worst-case global heating scenarios may need to be revised upwards in light of a better understanding of the role of clouds, scientists have said.
Recent modelling data suggests the climate is considerably more sensitive to carbon emissions than previously believed, and experts said the projections had the potential to be “incredibly alarming”, though they stressed further research would be needed to validate the new numbers.
Modelling results from more than 20 institutions are being compiled for the sixth assessment by the United Nations Intergovernmental Panel on Climate Change, which is due to be released next year.
Compared with the last assessment in 2014, 25% of them show a sharp upward shift from 3C to 5C in climate sensitivity – the amount of warming projected from a doubling of atmospheric carbon dioxide from the preindustrial level of 280 parts per million. This has shocked many veteran observers, because assumptions about climate sensitivity have been relatively unchanged since the 1980s.
“That is a very deep concern,” Johan Rockström, the director of the Potsdam Institute for Climate Impact Research, said. “Climate sensitivity is the holy grail of climate science. It is the prime indicator of climate risk. For 40 years, it has been around 3C. Now, we are suddenly starting to see big climate models on the best supercomputers showing things could be worse than we thought.”
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The role of clouds is one of the most uncertain areas in climate science because they are hard to measure and, depending on altitude, droplet temperature and other factors, can play either a warming or a cooling role. For decades, this has been the focus of fierce academic disputes.
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“Clouds will determine humanity’s fate – whether climate is an existential threat or an inconvenience that we will learn to live with,” said Palmer. “Most recent models suggest clouds will make matters worse.”
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“It’s really important. The message to the government and public is, you have to take this high climate sensitivity seriously. [We] must get emissions down as quickly as we can,” he said.
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While acknowledging the continued uncertainty, Rockström said climate models might still be underestimating the problem because they did not fully take into account tipping points in the biosphere.
“The more we learn, the more fragile the Earth system seems to be and the faster we need to move,” he said. “It gives even stronger argument to step out of this Covid-19 crisis and move full speed towards decarbonising the economy.”
https://www.theguardian.com/environment/2020/jun/13/climate-worst-case-scenarios-clouds-scientists-global-heating