... the Artic melting and ice ages. It detailed research that concluded that once the Arctic melted, it would cause an ice age. If I remember correctly, having the Arctic open would allow the water to evaporate from it and fall as snow on the surrounding land, which built up glaciers, which then traveled south to freeze deep into he continents (N. America and Eurasia). Water would flow through the Arctic, keeping it melted until the glaciers closed it off, which could take a very long time. Only once the Arctic was closed off could it freeze again and end the ice age.
The following are my own speculations:
The addition of a lot of carbon into the atmosphere could keep the glaciers from closing off the area, thus prolonging the ice age, although it might also keep the glaciers from getting quite as big or reaching as far south. Glaciers would normally reflect sunlight, cooling the planet, but again I would guess that the extra carbon would slow the process - like everything has to get frozen in order to allow the Arctic to get cut off, freeze, and end the ice age. So it may be slightly less painful but significantly longer.
It's also worth noting that there will be a delay between rising temperatures, melting Arctic, and the onset of an ce age. Sea levels will rise and flood a lot of land, then the glaciers will form, lower the sea level, etc. There's a whole sequence of states that the planet will have to go through.
It should be pretty obvious that the Earth will probably be unable to support the population of people we have during this process. It's unlikely that it could continue to support this many for long even without an ice age. Available land for farming will be limited, as well as habitable land. Burning more fossil fuels could actually limit the severity of the ice age but it would also prolong it, and getting to the fossil fuels would, in some regions, require getting under glaciers - probably not too hard, but eventually fossil fuels will run out.
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