How Much Sea Level Rise Would be Avoided by Aggressive CO2 Reductions?

UPDATE 11/25: Here is another recent paper, by Schaeffer et al. in Nature Climate Change (PDF), with conclusions along the lines of the others summarized here: "mitigation measures, even an abrupt switch to zero emissions, have practically no effect on sea level over the coming 50 years and only a moderate effect on sea level by 2100."

UPDATE 11/2: At the Washington Post @bradplumer follows up this post with his own, providing a nice summary of the issue. He concludes: "aggressive steps to cut emissions could reduce the amount of sea-level rise by somewhere between 6 and 20 inches in 2100, compared with our current trajectory" -- which is just about exactly where I came out in the dicussions with him and several others (thanks JG), 10 inches +/- 10 inches.

UPDATE: Via Twitter @bradplumer points me to a newer paper that suggests perhaps 7 inches is the difference in seal  level rise to 2100 between the highest and lowest RCP scenarios. It is not apples to apples with the number presented below, but still a very small number. And another paper here, with perhaps 10 inches between RCP scenarios, a number lower than the projection uncertainties.

One of the more reasonable discussion points to emerge from efforts to link Hurricane Sandy to the need to reduce carbon dioxide emissions focuses on the role that future sea level rise will have on making storm impacts worse. Logically, it would seem that if we can "halt the rise of the seas" then this would reduce future impacts from extreme events like Sandy.

The science of sea level rise, however, tells us that to 2100 (at least) our ability to halt he rise of the seas is extremely limited, even under an (unrealistically) aggressive scenario of emissions reduction. Several years ago, in a GRL paper titled "How much climate change can be avoided by mitigation?" Warren Washington and colleagues asked how much impact aggressive mitigation would have on the climate system. Specifically, they looked at a set of climate model runs assuming stabilization of carbon dioxide at 450 ppm.

Here is what they concluded for sea level rise:

[A]bout 8 cm of the sea level rise that would otherwise occur without mitigation would be averted. However, by the end of the century the sea level rise continues to increase and does not stabilize in both scenarios due to climate change commitment involving the thermal inertia of the oceans ...

Eight cm is about three inches. Three inches. Then sea level rise continues for centuries.

Though it seems logical to call for emissions reductions as a way to arrest sea level rise to reduce the impacts of hurricanes, recent research suggests that our ability to halt the rise of the seas is extremely limited. With respect to hurricanes, we have little option but to adapt, and improved adaptation makes good sense.

Efforts to use future hurricane damages to justify emissions reductions just don't make much sense. Fortunately, there are far better reasons to focus on emissions reductions than hurricanes.

Postscript: This post was inspired by Michael Levi's discussion here. Thanks!

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