With the climate models of the latest Generation of researchers are from today, Monday, at at an international Workshop in Barcelona. The theme of the sixth “Coupled Model Intercomparison Project” (CMIP6) is to be compared with the latest models of with each other. In a guest post for the online magazine “Carbon letter” to describe the three British experts, the first results of these models. The climate sensitivity of the earth is therefore higher than previously assumed.
The new Generation of models can be described by a higher resolution of the processes in the climate system, the earth is warming at a doubling of the CO2 content of the atmosphere. This so-called climate sensitivity, is to determine, among other things, therefore, so difficult, because the influences of clouds and aerosols were included in the models. With the new models and greater computing power is now better possible, write Stephen Belcher from the British weather service, Olivier Boucher, from the Institute for climate modelling and Rowan Sutton National centre for Atmospheric Science at the University of Reading.
For about 50 years, the assessment of the research, by and Large, has remained the same: A doubling of the concentration of carbon dioxide in the atmosphere leads to a warming of about three degrees Celsius. The specified range of 1.5 to 4.5 degrees.
Why can not say research it in more detail? “The basic nature”, say the head of the Potsdam Institute for climate impact research, Johan Rockström, daily mirror Background to follow. “The earth would be only a hunk of stone without a living biosphere, could say very accurately how much the temperature will increase. Forests, oceans or soils can, however, absorb carbon dioxide emissions and discharged. There is therefore a need to understand how stable these systems are and how stable its capacity, carbon dioxide emissions, to provide a buffer. And, unfortunately, it looks as if the capacities of nature are not perhaps as stable as we once thought,“ said Rockström.
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A warming in the upper end of the range suggested already the fifth model comparison project, she moved to 2.1 to 4.7 degrees. The sixth model comparison project showed a range of 2.8 to 5.8 ° C of warming for a doubling of CO2 levels.
“very bad news”
This number is valid for a very long period of time until the earth back to a state of equilibrium has been reached (Equilibrium Climate Sensitivity – ECS). Then, for example, distributed by the oceans absorbed heat. In contrast, the response of the climate system in the Transition (Transient Climate Response, TCR) is low. Here, feedback effects occur such as an increase in the water vapour content in the atmosphere, because of this increases with higher temperatures. And because water vapor itself is a greenhouse gas that increases the warming. The IPCC has the TCR in his 5. Progress report with up to 2.5 degrees.
The climate researchers now want to understand in Detail why some of the new models show this shift, it says in the guest post. The climate scientist Gerrit Hansen of German watch tweeted:
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“Should be confirmed these early results for the higher ECS values, that would be very bad news.” Oliver Geden, a policy Advisor with the focal points of climate and energy, expects a Neuaufflammen the discussion of the Removal of CO2 from the atmosphere.