The better question is what caused the Mini ice age that happened in North America when there was no human causations to contribute toward the climate change of that period? Can we blame it on the animals of that era?
Maybe we should kill all the animals to make the alarmists happy? How about we do Bill Gates' thing and start killing off the population to a number that makes Billy Boy happy. He should be the first volunteer to become deceased.. Think he'll do it? Not a chance. He believes he is God's gift to mankind.