So this is not really about settled science, and it's not really about CO2?

Alarmist Yulsman: James Hansen: Reduce CO2 in atmosphere or face catastrophe | CEJournal

With his characteristic under-stated manner, Hansen made a compelling case. But after speaking with two NOAA scientists today, I think Hansen put himself in a familiar position: out on a scientific limb. And after sifting through my many pages of notes from two days of immersion in climate issues, I’m as convinced as ever that journalists must be exceedingly careful not to overstate what we know for sure and what is still up for scientific debate.

Crawling out on the limb, Hansen argued that global warming has already caused the levels of water in Lake Powell and Lake Mead — the two giant reservoirs on the Colorado River than insure water supplies for tens of millions of Westerners — to fall to 50 percent of capacity. The reservoirs “probably will not be full again unless we decrease CO2 in the atmosphere,” he asserted.
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In my conversation with Tans and Hoerling today, I saw a tension between what they believe and what they think they can demonstrate scientifically.

“I like to frame the issue differently,” Tans said. “Sure, we cannot predict what the climate is going to look like in a couple of dcades. There are feedbacks in the system we don’t understand. In fact, we don’t even know all the feedbacks . . . To pick all this apart is extremely difficult — until things really happen. So I’m pessimistic.”
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Hoerling says we are living like the Easter Islanders, who were faced with collapse from over consumption of resources but didn’t see it coming. Like them, he says, we are living in denial.

“I think we are in that type of risk,” Tans said. “But is that moving people? It moves me. But I was already convinced in 1972.”