evidence: Sometimes, scientists themselves make apocalyptic claims. "It’s difficult to see how we could accommodate a billion people or even half of that," if Earth warms four degrees, said one earlier this year. "The potential for multi-breadbasket failure is increasing," said another. If sea levels rise as much as the Intergovernmental Panel on Climate Change predicts, another scientist said, "It will be an unmanageable problem." [...] Climate scientists are starting to push back against exaggerations by activists, journalists, and other scientists. [...] I asked the Australian climate scientist Tom Wigley what he thought of the claim that climate change threatens civilization. "It really does bother me because it’s wrong," he said. "All these young people have been misinformed. And partly it’s Greta Thunberg’s fault. Not deliberately. But she’s wrong."