Originally Posted by Bill8

The answer is complicated, altho the increased clouds model I mentioned would in theory only cool things down a few degrees. There are a bunch of problems with this cloud reflection model tho - the greenhouse gasses trap the infrared in at a much higher altitude than cloud cover, so nobody has any idea what will happen with a increased cloud cover scenario. It will certainly lead to stronger storms. It will certainly lead to snowier winters. BUT, it might not actually cool things down.

but the short answer to why increased heat is worse for our civilization than increased cold is desertification of both the land and the sea.

Colder sea water holds more oxygen, and is less acid, therefore the oceans create more life, more life at the bottom of the food chain. Hotter water is more acidic and holds less oxygen, leading to a type pf desert in the ocean. This is why the prime fishing areas are to the north and south, typically.

Colder land also supports more life - once desertification starts it tends to be permanent. Permanent on human scales at least - it lasts thousands of years.

Colder temperatures wouldn't force human migrations the way a band of desert girdling the equator will. The migrations have already begun, and they will get much worse as about 4 billion people are forced to try to reach parts of the earth that are less hot.

I'm not talking about a return to an ice age, altho everyone should know that global warming could, perversely, cause a shift in the atlantic and pacific conveyor currents as fresh water from melting ice changes the salinity that drives the conveyors. And that such a change in the conveyors could cause a short ice age.

really trying to explain the whole picture would take pages - one of the problems of the science and the models is that it's very complex.