Recent report published projecting values of sea-level rise 3

As anyone who reads my posts knows, I am a big fan of the IPCC reports. They are the best summary of what the scientific community knows about climate change and how confidently we know it.

A recent article (subscription required, sorry) in Science suggests that some scientists view the IPCC as overly cautious:

In the latest report, its fourth since 1990, the IPCC spoke for scientists in a calm, predictably conservative tone (Science, 9 February, p. 754). It is, after all, an exhaustive, many-tiered assessment of the state of climate science based exclusively on the published literature. In IPCC's Working Group I report on the physical science of climate, 600 authors contributed to an 11-chapter report that drew 30,000 comments from reviewers. The report was in turn boiled down to a 21-page "Summary for Policymakers" (SPM). Its central projection of sea-level rise by the century's end -- 0.34 meter -- came within 10% of the 2001 number. And by getting a better handle on some uncertainties, it even brought down the upper limit of its projected range, from 0.89 to 0.59 meter.

The SPM did add that "larger values [of sea-level rise] cannot be excluded." Whatever has accelerated ice-sheet flow to the sea, the report said, might really take off with further warming -- or not. "Understanding of these effects is too limited" to put a number on what might happen at the high end of sea-level rise, it concluded. Lacking such a number, the media tended to go with the comforting 0.34-meter projection or ignore sea level altogether.

I have two conflicting views of this.

On one hand, this is something of a distraction. The reason we don't have effective policy on climate change is not science or scientific uncertainties. The debate has moved past that, and now focuses on issues like fairness and economic impact. Arguments about science are used by those opposing action to hijack the debate.

On the other hand, it may be that a darker vision of possible futures would aid those favoring action. There is some debate about this, with some arguing that framing the debate in terms of dire futures is not effective.

Overall, I don't think the IPCC should change much. It has proven to be an effective summary of the science, albeit one that represents a "lower limit" of the harms of climate change. Regardless of what the IPCC says, there will be those advocates who willfully misrepresent it to advance their agenda.

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