A new paper by a group of distinguished climate scientists asks, “How much climate change can be avoided by mitigation?” This is of course an interesting and valuable question that too rarely is addressed. The paper suggests that mitigation can do very little to arrest sea level rise to 2100, here is the paper’s discussion of sea level rise:

The sea level rise from thermal expansion of the ocean (note that adding glacier and ice sheet melt could more than double this number [IPCC, 2007]) is 22 cm in the nonmitigation scenario and 14 cm in the mitigation case. Thus, about 8 cm of the sea level rise that would otherwise occur without mitigation would be averted (Fig. 1d). 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 [Meehl et al., 2005]. Recent studies indicate some acceleration of glacier melt over Greenland [e.g. Joughlin et al., 2008]. Increased ice sheet calving could lead to a more rapid sea level rise that would continue for several centuries after greenhouse gas concentrations are stabilized irrespective of the emission scenario.

Thus, according to this model, with aggressive mitigation sea level rise would be slowed by about 3.5 inches by 2100 (or maybe double this amount), but would continue in either scenario (mitigation versus business as usual). Thus, for the 21st century sea level rise is an adaptation issue, not a mitigation issue. The benefits of mitigation for sea level rise, according to this paper, stretch far out past 2100, which really limits its significance in the assessment of 21st century costs and benefits of mitigation.

The paper says more, which I will follow up on, but the implication of mitigation for sea level rise seems worth highlighting.