It will be far easier to stop the greenhouse effect on Earth than to find and settle a suitable exoplanet, or to terraform Mars. Space exploration is a worthy goal, but it is far harder than, and no substitute for, keeping our own planet habitable. The logical sequence is simple: fusion reactors, renewable energy, freedom on Earth; then fusion rockets, exploration, and discovery in space. Even if this sequence somehow did not hold, it is implausible that we could establish order in the universe if we cannot do so on our home planet.
