However, the solution of migrating the Earth to a more distant orbit would be permanent! And although we’d have to push our orbit out quite considerably to keep temperatures constant, timescales of hundreds of millions of years give us plenty of time, if we need it. To cancel out an effect of a 1% increase in the luminosity of the Sun, we’d need to push Earth an additional 0.5% away from the Sun; to cancel out an increase of 20% (what we expect over the next 2 billion years, total), we need the Earth an extra 9.5% more distant than we are now. Instead of the Earth being a mean distance of 149,600,000 km from the Sun, we’d be looking at more like 164,000,000 km.

This is going to take a lot of energy! To move the Earth — all six septillion (6 × 1024) kilograms of it — that extra distance away from the Sun is going to change our orbital parameters by quite a bit. If we were to push Earth’s mean distance from the Sun out to 164,000,000 km (102 million miles), there would be some significant changes we’d notice…