NEW YORK ( TheStreet) -- How do you invest if you believe man-made global warming is about to decimate the planet? And how do you invest if you think that's a lot of hooey?Most would say those who deny global warming should first bet on coal, oil and gas, but that's no way to make money. If you think your thesis is right, you bet on stocks that go against the other way of thinking. So if you accept the scientific consensus that glaciers are melting, temperatures are warming and we're heading over the environmental cliff, you look to sectors that can deal with that reality. Thus, those who think we can keep pumping methane and CO2 into the air without consequence would be wise to buy insurance stocks, especially those that insure against natural disasters. Companies like American International Group ( AIG) and Chubb ( CB) have to be putting more disasters into their models -- it wouldn't be prudent otherwise. If disasters don't occur, these companies are going to be rolling in cash. Best of all, they're both bargains. AIG still sells at slightly less than 12 times its most recent earnings, Chubb at a little more than 12 times. Retailers with global reach should have steady profits if global warming isn't real. So try some Wal-Mart ( WMT), even Target ( TGT), which should see both growth and international expansion. If you don't think Florida is doomed by climate change, maybe you should consider homebuilders. Lennar ( LEN) is a homebuilder based in Miami, which will be completely under water if global warming proceeds as expected. You may also think that in this case there will be lots of extra money around, so how about a gambling stock like Las Vegas Sands ( LVSC) -- Macau is right on the seacoast so it should be fine, right? Scientists think airliners contribute as much as one-fifth of the Arctic's global warming, so no cool planet portfolio should be without companies like Delta ( DAL) that fly over it every day. On the other hand, what if you accept the reality of global warming? How do you invest then?