The thermonuclear hit could conceivably melt Mars' polar ice caps which in turn would release carbon dioxide into the atmosphere. Musk believes that this would then create a kind of greenhouse effect which would expedite a version of climate change that would create conditions similar to what we experience on earth.
He phrased it a little differently, though. On Friday morning, the SpaceX founder reaffirmed his intentions with the following tweet;
Thankfully, the colonization of Mars will come with some “fire” merch.
Musk has been on his “nuke mars” scheming for a while now. Watch him lay it out for Colbert back in 2015.