When someone dies, their ideology immediately becomes subject to being revised, hijacked, twisted, and perverted toward ends that they never would have imagined in their lifetimes.
I doubt Marx would have endorsed the horrors that were latter carried out in his name by self-interested dictators. Similarly, I doubt Jesus would have endorsed the Crusades, the Inquisition, the Catholic Church and Southern Baptist pedophile scandals, and many other barbarities carried out down through the centuries by so-called "Christians."
If Marxism includes everything that's been done in the name of Marx, then it's a barbaric philosophy indeed. But if it's limited to only what Marx wrote, then it's a harmless economic theory. Same with Christianity. Christ's teachings themselves are quite moral and based. But you'd have to be a fool to endorse everything "Christians" have done.
Long story short: we don't know what Marx would have thought about climate change. His writings were about economics, not planetary science, and his death predates the first predictions of manmade climate change by over a decade.
