Increase in temperature could actually increase agricultural output long term. Melting ice in Greenland and in Antarctica could provide the fresh water. Also, there's no fundamental reason why human population should increase indefinitely. Perhaps it will stabilize to an environmentally sustainable level. By the way Pangaea was mostly a desert due to it's smaller ratio of shoreline length to landmass. My main point is that I don't know which way is "better": global warming could be bad, or it could actually be good, or overall irrelevant (bad in some places, good in others). I do not know if anybody actually knows this.