[palmer]

Forestalling or preventing Greenland ice sheet collapse might be considered a climate benefit

Impossible to say. Again, no quantitative analysis of how the sheet will collapse (showing how it can turn into a big slush pile and flow into the ocean).

So might preventing loss of biodiversity and preservation of coral reefs (taking a double hit due to increasing SST and ocean acidification).

A bit more valid, but still needs quantifying.

[cogitator]

Again, no quantitative analysis of how the sheet will collapse (showing how it can turn into a big slush pile and flow into the ocean).

I expect Richard Alley's still working on that one. Have you seen the most recent results on the thinning of the glaciers in southern Greenland?