Lower Maximum Global Warming Cap?
The maximum temperature increase that could occur in the future as a result of the increasing concentration of greenhouse gases in the atmosphere is around 6.2 Kelvin, which is probably significantly lower than previously forecast.
Most climate simulations predict future average warming of the earth, which should cause average temperatures between 1.5 and 4.5 Kelvin higher in a global comparison. However, individual studies go far beyond this and even calculate mean values that are up to 9 Kelvin higher. According to Gabriele Hegerl from Duke University and her colleagues, however, this maximum range of variation can be limited if reconstructions of climate developments in the northern hemisphere over the past 700 years are taken into account.
The scientists fed their so-called energy balance model with current and historical climate data such as temperature measurements, tree ring or ice core evaluations and the respective solar and volcanic activities as well as the greenhouse gas concentrations in the atmosphere. Then, in a thousand computer runs, they calculated the temperature development over a total of a thousand years – including 300 years in the future.
The sensitivity of the climate was compared exclusively with the development of the temperatures in the northern hemisphere, since the database for this region is sufficiently large to allow for corresponding reconstructions. On the one hand, the models confirmed the upward trend in temperatures since the beginning of industrialization. At the same time, the researchers working with Hegerl came to the conclusion, based on the observed developments, that if the carbon dioxide concentration in the earth's atmosphere doubles, there is a 90 percent probability that the temperature will only increase by a maximum of 6.2 Kelvin.
In your opinion, this is the largest possible range of fluctuation in the earth's climate, since even higher amplitudes would be cushioned - for example through interactions between the atmosphere and the oceans.