Who knew Fidel Castro was a greenie — and a pessimist?

The former Cuban leader doesn't speak out that often. Usually, when he does, it's to tell everybody that he's not dead yet. 

This time, he penned a column in Cuban state media to express his concern about two things: nuclear war (the Yankees' fault, natch) and climate change — specifically the dangers of fracking.

Fidel Castro has surfaced once again.

Usually, this means either that he wants to reassure everyone that he's not dead, or that he feels the need to reassert his dislike for the United States.

This week, it was the latter. 

Castro wrote a letter to state media in response to a comment from U.S. President Barack Obama, who had said he would only change U.S. policy toward Cuba — which mostly amounts to a 50-year economic embargo, travel restrictions, and serious brow-furrowing — if the island changed first.

Castro had something to say about that. "How kind! How intelligent!" he wrote, in an article published in state media. When change comes to Cuba, Castro added, it won't be because of Washington.

"Perhaps that empire will fall first," he added. He also called Obama "stupid." That's on top of his comment earlier this week after Obama's address to the United Nations' General Assembly, which Castro deemed "gibberish."