Global Warming's US Impacts and "Permanent Drying" in the Southwest

By Joseph Romm, Climate Progress. Posted December 18, 2008.

A major new report warns that on our current emissions path, we face the severe risk of abrupt climate change impacts. The basic conclusions themselves are nothing new — see "Startling new sea level rise research: "Most likely" 0.8 to 2.0 meters by 2100" and "Australia faces the "permanent dry" — as do we."

But what is stunning is that these warnings come from the United States Geological Survey — the Bush Administration (!). This new science-based report, Abrupt Climate Change, is thus a sobering book-end to the fantasy-based talking points released by the Administration today on how the President has "Taken Constructive Steps To Confront Climate Change."

This is a first-rate report from the USGS’s Climate Change Science Program. I highly recommend reading, Chapter 2, "Rapid Changes in Glaciers and Ice Sheets and their Impacts on Sea Level," and Chapter 3, "Hydrological Variability and Change." The chapters are much more readable than the IPCC reports, and the two together will make anyone an expert on what are perhaps the two most dangerous climate impacts that threaten this country.

The sea level rise conclusion, "based on an assessment of the published scientific literature" is:

Recent rapid changes at the edges of the Greenland and West Antarctic ice sheets show acceleration of flow and thinning, with the velocity of some glaciers increasing more than twofold. Glacier accelerations causing this imbalance have been related to enhanced surface meltwater production penetrating to the bed to lubricate glacier motion, and to ice-shelf removal, ice-front retreat, and glacier ungrounding that reduce resistance to flow. The present generation of models does not capture these processes. It is unclear whether this imbalance is a short-term natural adjustment or a response to recent climate change, but processes causing accelerations are enabled by warming, so these adjustments will very likely become more frequent in a warmer climate. The regions likely to experience future rapid changes in ice volume are those where ice is grounded well below sea level such as the West Antarctic Ice Sheet or large glaciers in Greenland like the Jakobshavn Isbrae that flow into the sea through a deep channel reaching far inland. Inclusion of these processes in models will likely lead to sea-level projections for the end of the 21st century that substantially exceed the projections presented in the IPCC AR4 report (0.28 ± 0.10 m to 0.42 ± 0.16 m rise).

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