This may have to do with something other than war criminals. In 2016, the ICC published a policy paper that delineated how environmental crimes could be prosecuted under Crimes Against Humanity. Environmental crimes may include:
“illegal exploitation of natural resources, arms trafficking, human trafficking, terrorism, financial crimes, land grabbing or the destruction of the environment.”
Trump’s actions against renewable energy, his guidelines for the EPA, and the decades-long anti-science propaganda campaigns by the Koch brothers, Rush Limbaugh, etc, and fossil fuel companies might all well qualify for prosecution.
I gotta say, if the Dems take back the House and Senate, and then the Presidency, joining the ICC and prosecuting the propagandists could be the most effective way to end fossil fuel use. It could clear the way for government mandates to simply fix the problem.