They shouldn't be using the word 'apocalypse', but the end of capitalism wouldn't save the planet. We've already passed the point of no return, and switching to communism will just distribute the wealth more evenly, it won't stop humanity from consuming massive resources, especially in the West. Communists expect all the things they have under capitalism to continue once they get their revolution, so ignoring how utterly unlikely it is that billions of people suddenly decide they want to fight a bloody war against the states (that are armed to the teeth) and capital (even more armed) to achieve communism, communism isn't going to halt the collapse of the ecosystem that has already turned much of the world to desert or sea. All the science shows that collapse is inevitable. All history shows us that every empire collapses - this being the most unsustainable and polluting empire of all - the collapse will be utterly gigantic.