Nobel winning economist Paul Krugman wrote that by 2005, it would become clear that the Internet's effect on the economy is no greater than the fax machine's.

Climate scientists can model the climate to a certain degree but they're not all-knowing oracles. They are not qualified to predict future societal collapses, wars or even famines. The idea that a gradual 2.0 °C temperature rise spread over decades would necessarily cause such things just doesn't pass the smell test.