On Earth Day, President Obama stated that the earth is "the only planet we got." Obama was apparently unaware of the fact that there are millions of earth-like planets just in the Milky Way Galaxy, not to mention those in the billions of other galaxies.
(Warning: this is satire)
The human race may have only one economy--- but it has innumerable planets to choose from. When one planet becomes uninhabitable, the obvious solution is the so-called "Free Planet Project," inspired by New Hampshire's Free State Project.
This involves building a spaceship with a select group of liberty-minded job creators and nubile females, along with a few years supply of the bare essentials: Ayn Rand books, guns, ammo, medical marijuana, beer and survival food. As the "generation ship" travels to the next planet, onboard computers could generate Bitcoin for use on that planet. It takes about 1000 years for a typical consumer-grade computer to generate 1 BTC worth of bitcoin, which is the equivalent of US$1000.00. If the generation ship carries 1000 computers running for 10,000 years, once the colonists wake up from suspended animation, they would arrive with about $10 billion in seed capital to create jobs on the new planet.
If the planet turns put to be inhabited, the incumbent humanoids will doubtless welcome the newcomers with open arms (or tentacles as the case may be), because all humanoid beings yearn for freedom above all else. Inevitably, the incumbents will quickly all recognize that the newcomers are bringing them freedom. And let's not forget that the newcomers would also have 10 million BTC worth (or US$10 billion) of the universal currency Bitcoin to invest in the local economy. The newcomers would instantly have economic (and hence political) clout comparable to that of the Earth's Koch Brothers.
If the planet is uninhabited, the colonists can get right to work building a paradise with no taxes, no unions, and no government bureaucrats: a paradise where markets are perfectly free, where there are no regulations of any sort. and where job creators have nothing slowing down the process of creating jobs.
The only tricky part is choosing a planet which is warm enough. If the planet is a little too warm, it is possible to cool it down. If it's too cool, there is nothing you can do, thanks to the fact that there is no such thing as global warming.