For one, Yudkowsky in Artificial Intelligence as a Positive and Negative Factor in Global Risk says that artificial general intelligence could potentially use its super-intelligence to decrease existential risk in ways we haven't thought of. Additionally, I suspect (though I am rather uninformed on the topic) that Earth-originating life will be much less vulnerable one it spreads away from Earth, as I think many catastrophes would be local to a single planet. I suspect catastrophes from nanotechnology one such catastrophe.