Important review paper on sea level and ice melt

Today there's a new review article in Science, by a team of researchers led by Andrea Dutton from the University of Florida, Gainesville. It's a huge review, looking thirty years of research on the effects of melting polar ice sheets in past warm periods.

In contrast to the obviously very careful work by this team of scientists, building on very careful, clever and at times dangerous work by many other scientists, Anthony Watts stands on the sidelines with a foolish smirk. He acts like the pimply-faced wanna-be delinquent trying to act smart in front of his mates, while the rest of the class rolls their eyes if they notice him at all. Anthony wrote above his copy and pasted press release, his usual "claim" dogwhistle, and more (archived here):

Claim: 20-foot sea-level rise in our future (except nature isn’t cooperating so far)
From the University of Florida and the “road to paris, we have to get it done this time department” comes this claim. You gotta love the “out of equilibrium” part, where nature isn’t conforming to their expectations. The cartoon like graphic seems to be designed for grade school consumption, and seems to be equally out of equilibrium with observations so far.

Anthony Watts doesn't believe that ice melts when it gets hot. He's denied it on more occasions than I can keep up with. Maybe because he has seen so little ice in drought-ridden California that he's forgotten what it is.

Deniers typically have no sense of time either. If something that will happen in coming decades or centuries hasn't already happened then that's proof that it never will - in deniersville.

Enough of that nonsense. What about the paper itself. It's really well presented, with a "box" or sidebar giving background information, and lots of figures illustrating important points. The Editors summary reads:

We know that the sea level will rise as climate warms. Nevertheless, accurate projections of how much sea-level rise will occur are difficult to make based solely on modern observations. Determining how ice sheets and sea level have varied in past warm periods can help us better understand how sensitive ice sheets are to higher temperatures. Dutton et al. review recent interdisciplinary progress in understanding this issue, based on data from four different warm intervals over the past 3 million years. Their synthesis provides a clear picture of the progress we have made and the hurdles that still exist.

There's a figure in the paper that will grab the attention of many people. It shows the peak global mean sea level now and in past warm periods, and the source of all the water. (Anthony Watts didn't like it. He said it looked as if it was "grade school consumption". Going by his comments that means it's too advanced for him to understand.) Click to enlarge.

Fig. 4 Peak global mean temperature, atmospheric CO2, maximum GMSL, and source(s) of meltwater. Light blue shading indicates uncertainty of sea-level maximum. Black vertical lines represent GMSL reconstructions from combined field observations and GIA modeling; gray dashed lines are δ18O-based reconstructions. Red pie charts over Greenland and Antarctica denote fraction (not location) of ice retreat. Although the peaks in temperature, CO2, and sea level within each time period may not be synchronous and ice sheets are sensitive to factors not depicted here, significantly higher sea levels were attained during MIS 5e and 11 when atmospheric CO2 forcing was significantly lower than present. See tables S3 and S4 for data and sources. Source: Dutton15

I don't have time to go into any more detail right now. The main message, as shown in the above image, is that ice is going to melt, the sea level is going to rise by several metres. One important thing that still has to be worked out is how soon that will happen.

References and further reading

A. Dutton, A. E. Carlson, A. J. Long, G. A. Milne, P. U. Clark, R. Deconto, B. P. Horton, S. Rahmstorf, M. E. Raymo. "Sea-level rise due to polar ice-sheet mass loss during past warm periods." Science, 2015 DOI: 10.1126/science.aaa4019 DOI: 10.1126/science.aaa4019