re: #217 freetoken

Are you saying that 21st century warming will be even less human caused?

By the way, the “likely” vs “very likely”, 90% vs 95%, and such arguments are politically driven.

Go ahead and use 90% then. The bottom row gets 90%, the top row gets 10%.

Each additional molecule of carbon dioxide has a diminishing warming effect. That is to say, if we doubled CO2, all other things being equal, the climate would increase 2 degrees (made-up number), and if we doubled CO2 again, all things being equal, the climate would increase 1 degrees (again made-up, you get the gist). Therefore, the hypothesis that we will experience cataclysmic warming is based upon positive feedback loops. That is to say, doubling the CO2 will cause A, B, and C to happen and increase the warming even more. These include changes in cloud cover, the melting of the permafrost, and changes in the reflectivity of the Earth. Now, in the very limited time span that we have real climate observations to compare to models (SRES scenarios start January 1st, 2001, so roughly 9 years), the models are not performing well. This calls into question whether these positive feedbacks are being modeled correctly. Further, the current research suggests that cloud feedbacks are being modeled incorrectly and that instead of being a positive feedback, they are in fact possibly negative.

The science is a lot more nuanced and complicated than simply “we’re warming and there’s no stopping it.”