Whether or not SETI is the answer, I think we definitely need to be looking for a second planet. Two major issues are overhanging our future.
1. We are using fossil fuels faster than Earth produces them. I have no idea when "peak oil" has passed or will pass, but I don't have to be precisely correct anyway. It's not arguable; the mathematics just don't support endless supplies of fossil fuel (of any kind). Even if we stop burning it, we'll still use petroleum for everything else. So eventually we will run out anyway, or it will be so hard to extract that it might as well be gone. Our population is several orders of magnitude too large to be fed, clothed, and medicined by non-petroleum sources. I think even in the worst (best?) case scenarios, we'll run out of fuel long before we pollute the place bad enough to make life impossible here.
2. Eventually, we will have a major calamitous event that will cause pollution millions of times worse than we're even capable of imagining. Could be one or more major earthquakes (there are several pressure-points that are currently overdue), a meteor of major proportions (has happened at least twice before), or a supervolcano such as the devil's own caldera currently underneath Yellowstone. Vesuvius, Pele, and St. Helens were peacefully-sleeping babies compared to Yellowstone's past history. The next time that one pops, nothing else will matter. The pyroclastic flows and ash fallout will probably destroy large swaths of arable land from Canada and the US. Year-round winter will make it hard to grow anything in many other places on the planet, for at least several years, so crops and then livestock could die off, followed by a major percentage of the population which depends on the food that the land can support. Survival could become a full-time job for anybody still alive after the first couple years, and "Global Warming" will be nothing more than a wet dream at that point.
Even though it could be hundreds of years for either of those things to happen, I think we need to be looking for a second planet. It could take a hundred years just to develop FTL travel (if it's even possible), and then several hundred/thousand more to just find someplace where stuff grows. Although we are industrious, we silly humans are also notorious for our procrastination.
Last edited by BIF
on Fri Sep 25, 2015 8:29 pm, edited 1 time in total.