> They have nuclear designs which are 98% fusion. The radioactive fallout for these is much more limited. > For example, atomic lake (which was terraformed wit

> They have nuclear designs which are 98% fusion. The radioactive fallout for these is much more limited. > For example, atomic lake (which was terraformed with nuclear bombs), has radiation levels of 9 µSv vs 3 from background per week It's kind of weird to take an authoritative stance with that example. "atomic lake" was from an underground detonation of a moderate-yield fission device 50 years ago and largely just moved dirt around while still sending up detectable radioactive waste. OK, you can go near the lake now without ill effect but you've accomplished...what exactly? So scale it up to what is actually needed to vaporize a meaningful amount of the ice caps and look at how effective that would be at making a dent in the Martian atmosphere and the GP has a very good point. It's not a workable idea.