I'm not sure what to take from the natural comment or if it's serious... Natural things can be profoundly bad for the earth and things that live on it, like poison... Or volcanos...
Also salt water, incredibly natural it turns out.
https://en.wikipedia.org/wiki/Soil_salinity
https://en.wikipedia.org/wiki/Salting_the_earth
Agreed, being natural is not necessariliy good. Solar flare, hurricanes, typhoons, tornadoes, eathquakes, polar ice cap and glaciers melting are all natural phenomena. Mabye they're good for the planet but not good at all for the puny earthlings, us.
Also, "we'll just do it over the oceans where impact should be limited" is risk prone, just like controlled burns.