Dr Patrick J Michaels, the chief science disinformer from the Cato Institute, tells WUWT-ers what climate hawks already knew, that during the Eemian, it's likely that Greenland ice sheet only contributed maybe a couple of meters of the large sea level rise.
The good news...?
From ScienceDaily back in January this year:
Jan. 23, 2013 — A new study provides surprising details on changes in Earth's climate during the last warm period (120,000-128,000 years ago). Even though temperatures in Northern Greenland were 5-8 degrees Celsius higher than today, the thickness of the ice sheet was only a few hundred meters lower. And this despite the fact that sea level was 4-8 metres higher than today.
This indicates that the melting of the Greenland ice sheet may have contributed less than half of the total sea level rise at the time. This interglacial period (the so called "Eemian") may be a good analogue for where the Greenland ice sheet is heading today in the face of increasing greenhouse gases and warming temperatures.
But then Michaels writes a load of crap that he's tried on before:
Whew! Thus does one revolutionary paper shoot pretty much the entire global warming sea-level catastrophe—the one worth being concerned about—through the heart. Antarctica is so cold that it is projected to gain ice in the coming century, as slightly increased precipitation—which may have recently been detected—falls as more snow, which compacts into more ice.
Wrong! Wrong! Wrong!
The bad news!
Back to ScienceDaily (my bold):
"A thick Greenland ice sheet connected to much warmer conditions in Greenland is astounding but no reason to relax and watch what the future of human-made warming has in store for us," says Prof. Hubertus Fischer, ice core scientist at the University of Bern. "Fact is that the warming was accompanied by a sea level rise of 4-8 metres. Such a sea-level rise would be a disaster for the more than 7 billion people living on this planet today, even if it takes a couple thousand years to be reached."
The apparent good news from this study is that the Greenland ice sheet may not be as sensitive to temperature increases as previously thought. However, the bad news is that if Greenland did not disgorge larger parts of its ice into the ocean during the Eemian, then Antarctica and here especially the more climate sensitive West Antarctic Ice Sheet must be responsible for a significant part of the 4-8-metre sea level rise and may be even more sensitive to climate warming than previously thought.
D. Dahl-Jensen et al. Eemian interglacial reconstructed from a Greenland folded ice core. Nature, 2013; 493 (7433): 489 DOI: 10.1038/nature11789
About Antarctica
Yes, there were some heavy snowfalls in East Antarctica for a couple of seasons last decade. But that's more than offset (times over) by West Antarctica and the Peninsula, which have always been regarded as where the first sea level rise will come from in Antarctica. And the way we're going it will probably start in earnest before this century is done.
You can read some recent papers on Pine Island glacier here courtesy Google Scholar.
I wrote recently about a new paper on Antarctica that studies the pattern of melting ice shelves around the entire continent. Ice shelves slow the flow of the rivers of ice. (Click for larger version.)
One other thing to be aware of is that the object of this study is the height of the Greenland ice sheet over many thousands of years (or kyrs, as the in-crowd says). This is probably a good descriptor of the behaviour of the ice sheet as a whole, which is a huge mass with a similarly huge thermal inertia. Losing 25% of its mass, i.e., 1.5 m of sea-level equivalent, over 8 kyrs amounts to 0.2 mm/yr, which may seem like almost nothing. But, the edges of the GIS may respond much more strongly initially, though on a shorter time scale. We know, e.g., that Jakobshavn Isbræ has done so --- the disturbance propagating backward up the ice sheet, and presumably levelling off. Same for other glaciers and ice caps, and for the fringes of Antarctica. And even if this would level off over centuries, say, this still wouldn't help us much by 2100.
ReplyDeleteIt sure is interesting how WUWT picks and chooses when to accept climate science and when to attack it.
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