Global temps have been mostly consistent the past few thousand years, sometimes trending slightly up and sometimes slightly down, within half a degree (C), when suddenly, beginning around the same time as the industrial revolution, it starts to jump up like a bat out of hell 1.0-1.5 degrees in an extremely brief amount of time.
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Now yes, that could be a coincidence, but it's unlikely to be such a coincidence.
You could make the argument that the temp increase could be a normal rise, as the temp has ebbed and flowed up and down that much and more over millions of years. And it has. BUT NOT IN SUCH A SHORT TIME.
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So a logical person (or dare-say an expert) can look at the sudden rise being in lockstep with humans beginning to heavily burn fossil fuels AND this radical increase occurring over 150 years instead of 15,000 years and conclude, prudently, that people have had something to do with it.
I don't get why this is so hard and some people want to resist what's right there in front of their faces. When if was something more benign for them and didn't interfere with their tribe's ideology, they'd otherwise acknowledge the point.