The same condition would hold true if the Siberian or Deccan Traps (sheet lava fissures) were to restart. It is also possible that Yellowstone or Toba super-volcanos erupt. It is also possible that we could get another Chicxulub impact which might do a little more damage.
What I do not know from this writeup is that if the authors took into account offsetting effects that could potentially mitigate the full scale damage they describe? We KNOW that increased temperatures are very likely to increase cloud formation and reflect heat out into space. However this is a computation that is beyond almost all computing and modeling. You are talking about cubic miles of atmosphere from the surface to the stratosphere and all the variables that can effect the same.
Do they take into account the Antarctic isolate weather zone which, being surrounded by open water, serves to keep the continent in the deep freeze?
Do their studies assume any equilibrium factor other than clouds as the Earth does radiate heat over the night side and takes up heat over the open ocean? The longer the time span of fossil fuel use, the more these effects will modify the results.
Do they have any adjustments for using non-fossil fuels like nuclear power?
So, ASSUMING the best of intentions, were any mitigating factors thrown into this modeling? What is their ‘fudge factor’ and which case are we hearing; worst, middle or best?
Actually, they lost me when they said all fossil fuels. We can now extract more oil than ever but there are still non-recoverable reserves. So I have a lot of questions about what appears to be such a bad scenario.
Answering my own query, from the Yahoo/Newsweek article on this study; “The paper takes a long view at the planet’s worst-case scenario.” The model appears to be based on the amount of carbon used and put into circulation. If ‘all’ is used, the quote is +9 celsius (+16.2 F) over current temps - “an unsustainable increase that would make the world unrecognizable!”