The phrase "to boil the ocean" means attempting to solve a problem or achieve a goal that is impossible or too difficult to accomplish. Full definition
... One of the things that we talk about in this work is you can't boil the ocean. (timesunion.com)
Talk about boiling the ocean to satisfy a frivolous complaint. (remonline.com)
As it stands there's no empirical evidence of any sort that CO2 causes climate warming, and indeed now the ipcc is maintaining that CO2 is both a cause and an effect of temperature change, which, unless CO2 was only an insignificant contributor to warming, would without a doubt lead to a runaway greenhouse with boiling oceans. (wattsupwiththat.com)