During the recent presidential debate, a number of candidates suggested that global warming represents an existential threat to mankind, and thus requires dramatic and immediate action.
Governor Jay Inslee has been particularly generous in the use of this term, but he is not alone. Kamala Harris, Cory Booker, Bernie Sanders and Elizabeth Warren have said the same thing, as have several media outlets and environmental interest groups.
Some of these folks also claim that the window for action on climate change is closing–Jay Inslee suggests that the next president will be the last able to take effective steps. Others suggest 10 or 12 years.
But are these existential threat claims true? That is what we will examine in this blog.
An existential threat is one that threatens the very existence of mankind. Something that is a simply a challenge or an inconvenience is not an existential threat. An existential threat must have the potential to undermine the very viability of human civilization.
As described below, global warming is a serious problem and its impacts will be substantial—but in no way does it seriously threaten our species or human civilization. And with reasonable mitigation and adaptation, mankind will continue to move forward—reducing poverty, living healthier lives, and stabilizing our population.
What do current climate models tell us? These models are run under specific scenarios of emission of CO2 and other greenhouse gases (see figure). In one, RCP8.5, we simply continue doing what we are doing, with escalating use of coal and oil. Not much renewable energy. Many believe this scenario is too pessimistic. Much more reasonable is RCP 4.5, which has modestly increased emissions through 2040, declining after 2050. I suspect this one will be closer to reality.
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