(Apologies to Wyclef Jean.)
Jeff Sachs, head of Columbia University's Earth Institute, is all worked up over climate change, particularly the possibility of millions of 'climate change refugees,' those who are motivated to migrate because of environmental stress. Sachs catalogues his guesses about what will happen in India, Africa, and Asia in the next few decades (water stress, mainly) and calls for economists, hydrologists, agronomists, and climatologists to get on with it and figure out a solution. He notes:
Some hard-hit places will be salvaged by better infrastructure that protects against storm surges or economizes on water for agriculture. Others will shift successfully from agriculture to industry and services. Yet some places will be unable to adjust altogether, and populations are likely to suffer and to move.
Interesting description -- sounds like the history of human evolution and migration, dangerously accelerated. But okay: the world is different now. Smaller, fewer natural resources left, more full of people; there's no place left to absorb displaced populations. (Remember the US trying to absorb a million Katrina evacuees?) One could argue, though, that this is merely the speeding up of an inevitable process; we were bound to run out of space and/or stuff eventually.
Some possible outcomes:
1. Space colonization. Well, obviously. Will have to happen sooner or later, but not clear whether it can happen quickly enough to solve the 'climate refugee' problem.
2. Genetically modified crops. Despite the historical hostility of environmentalists to GM crops, they stand a good chance of mitigating the water problem -- crops that require lots of water (corn, rice, cotton, grass for pasturing) can be engineered to need less. This can't hold off Malthus forever, but will almost certainly be part of the solution.
3. Limited population growth. Not a bad idea (until aforementioned space colonization is feasible) but also not too likely, going by recent stories of Chinese women using fertility drugs to circumvent the government's one-birth policy.
4. More efficient food distribution. By most estimates, North America already has the production capability to feed the whole world; rotting grain in Iowa silos represents an alarming combination of market failure and government failure. There is surely some way to improve this.
5. Efficient clean energy. Another no-brainer -- we already knew that even running all our current alternative energy sources at max capacity, and continuing to burn fossil fuels at the same rate, we're on track to run out of energy by 2050 or so. A point about this, though: if climate change produces catastrophic drought in the middle east, coal and oil prices will likely plummet, making it easier to rationalize continuing reliance on these sources, at least until these economies collapse completely.