… our best estimates today are that surface warming stops when carbon emissions stop, i.e.that there is no additional surface warming in the pipeline when emissions reach zero. The notion that there are decades of committed surface warming after emissions reach zero is based on outdated simulations that did not take into account the interactive role of the ocean carbon cycle. While the science on this is more than a decade old, this significant paradigm shift in our understanding of committed warming has still failed to be widely understood or recognized in much of the public discourse over climate science (see this op-ed I co-authored in the Washington Post about that last year). The point is that whether or not the 1.5C target is reachable is a matter of policy, not climate physics, at this point. It's fine for Jim and his colleagues to explore scenarios where we do not act soon enough, and carbon emissions are not lowered adequately to avert specific warming targets such as 1.5C or 2C, but it should be clear that the differences in their conclusions are a result of those policy and behavioral assumptions, not climate physics.

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Our paper, Global Warming in the Pipeline, was greeted by a few scientists, among the most active in communication with the public, with denial. Our friend Michael Mann, e.g., with a large public following, refused to concede that global warming is accelerating. We mention Mike because we know that he won’t take this notation personally. Accelerated global warming is the first significant change of global warming rate since 1970. It is important because it confirms the futility of “net zero” hopium that serves as present energy policy and because we are running short of time to avoid passing the point of no return. …