Says Michael Mann:
So 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 The notion that there are decades of committed surface warming after emissions reach zero is based on outdated simulations that did not take into account the interactive role of the ocean carbon cycle.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.
Comments on New Article by James Hansen | MICHAEL E. MANN (michaelmann.net)
Also says surface warming is not accelerating.
If we do nothing more, climate warming is limited to 3 deg C
climate models have the climate sensitivity (how much warming we can expect for a specified increase in carbon dioxide concentrations) about right, at least for the range of warming we are likely facing (less than 3C/5F given policies already in place).
The media’s exaggerated, hysterical news reports rely on RCP 8.5, which is well above these values – and which most believe is physically impossible. It assumes such things as a nearly order of magnitude higher coal consumption, when clearly, we are not heading in the direction. But there are thousands of simulation studies based on the unrealistic RCP 8.5 – being scary is more important than being right. These junk science papers drive the media’s demand for hysterics and fear.
