Japan has announced intentions to create a Moon Base by 2030. The US & China have plans too. One of the possible uses of such a base was outlined in an article in the NY Times, where a group of scientists & officials want to turn the Moon into Noah's Ark...
...the Alliance to Rescue Civilization, a group that advocates a backup for humanity by way of a station on the Moon replete with DNA samples of all life on Earth, as well as a compendium of all human knowledge -- the ultimate detached garage for a race of packrats.
If the world is destroyed by climate change, World War III or Bruce Willis isn't available to take out the giant asteroid, Humanity will have a
"possible" chance of starting over. Even if this backup plan didn't work, maybe Aliens or the species that comes behind us
(Dolphins start walking?) will find the repository & remember us....
However, there are alternatives. One of the most interesting involves possibly terraforming Mars by nuking it...
The 2 polar caps would be key in terraforming the planet, if tt's even possible. Scientists who researched what it would take to make Mars' habitable wrote a detailed paper on the technology & requirements needed. The Cliffs Notes version is that they proposed constructing & using orbital mirrors to melt the polar ice caps on Mars. The polar ice caps are water & frozen CO2 (dry ice). It's thought that if enough heat is able to melt the caps, the water & CO2 release could create a greenhouse effect & thicken the atmosphere.
Since we don't nearly have the technical ability to construct, launch and tow a mirror large enough to do the job, others have thought up a "quick & dirty" way to make it happen...
Instead of mirrors, we would get rid of some of our nuclear weapons stockpile by launching on Mars. It might melt the caps, but it would contaminate the Martian environment with radiation.
If you could melt the Martian polar caps & not "overdo" the radiation, the excess CO2 would be used to introduce oxygenating plants. Maybe through the use of genetically modified plants that could survive in the environment & produce the needed gases, we would seed the planet with flora. If you jump through all of those hoops (and some more probably known & unknown), by the time everyone reading this is long dead & gone, you might get a Mars that looks like this...
Some of the things that will have to be overcome...
- The Right Mix - Getting the right mix of gases in the atmosphere, so it would mirror Earth, may be practically impossible. Earth's atmosphere is 77% nitrogen, which acts as a buffer gas, where the present Martian atmosphere only has 3% nitrogen.
- Destroying The Native Martian Environment - If we tried to do something like this now, or even after we someday send astronauts to Mars, would it be ethical or right to destroy Mars current environment, especially if primitive life existed there. What if it was just microbes in the dirt?
- No Magnetic Field - Mars doesn't have a magnetosphere like Earth, which means it's succeptible to cosmic radiation. The creation & thickening of the atmosphere would be crucial in making any terraforming project.