Sea level threat worsens; Will Hawai'i respond?

A pulse of rapid sea level rise is possible during the coming decades—an eventuality that could devastate both Hawai'i's economy and its environment.

A new scientific report issued by the U.S. Climate Change Science Program suggests that abrupt climate change could occur during this century—and that it could happen faster than society's ability to respond.

(Image: Cover of the Abrupt Climate Change report.)

The report has severe implications for Hawai'i, but has received no press coverage in the Islands.
And the island state of Hawai'i, which launched no high-level coordinated statewide emergency planning effort when the Intergovernmental Panel on Climate Change earlier predicted potentially catastrophic sea level rise in coming decades, has remained incomprehensibly but consistently silent.

The latest study suggests that the IPCC estimates of sea level rise—as much as two feet above current levels—are too conservative.

This U.S. government study, which was submitted to Congress just before Christmas, is the most up-to-date reflection of the latest available climate science.

It has a number of significant subject areas, but for Hawai'i, among the most significant features are its concerns regarding the rapid change in glaciers and ice sheets, and resulting rapid rise in sea levels.

The report defines abrupt climate change this way: “A large-scale change in the climate system that takes place over a few decades or less, persists (or is anticipated to persist) for at least a few decades, and causes substantial disruptions in human and natural systems.”

The report says that the latest evidence is that the ice is melting far faster than current climate models anticipate:

“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.”

While oceanic ice like that around the North Pole can melt without raising sea levels (just as a glass of water with ice doesn't overflow as the ice melts), the mass melting of ice sheets on land do raise sea levels, since they add water to the oceans.

The last report of the Intergovernmental Panel on Climate Change (IPCC AR4) did not estimate ice loss from Greenland and Antarctica, saying the science at the time was not adequate to make those estimates. The latest study does the calculations based on new science, and it finds that glaciers in both locations are shedding water at an accelerating rate.

“Although no ice-sheet model is currently capable of capturing the glacier speedups in Antarctica or Greenland that have been observed over the last decade, including these processes in models will very likely show that IPCC AR4 projected sea level rises for the end of the 21st century are too low,” the report says.

The IPCC report anticipated sea level rise of half a foot to two feet by the end of the century. At those levels, it predicted the impact for small islands:

“Sea level rise is expected to exacerbate inundation, storm surge, erosion and other coastal hazards, thus threatening vital infrastructure, settlements and facilities that support the livelihood of island communities.”

The Abrupt Climate Change report said that in previous periods of loss of glaciers, sea levels have risen at a rate of 1 to 2 inches a year. In recent decades, sea levels have been rising at just an inch or so a decade.

It calls for more scientific work on ice sheets so that actual sea level rise can be more accurately predicted.

The document was released Dec. 15, 2008, by the U.S. Climate Change Science Program at the USGS, under the title, “Abrupt Climate Change. A report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research.”

It is a report to Congress, and it has been endorsed by the Bush Administration's secretaries of Commerce and Energy and the director of the Office of Science and Technology Policy.

Its lead authors are Peter Clark of Oregon State's Department of Geosciences and Andrew Weaver of the University of Victoria's School of Earth and Ocean Sciences. Contributing authors include Edward Brook of Oregon State's Department of Geosciences, Edward Cook of Lamont-Doherty Earth Observatory at Columbia University, Thomas Delworth of NOAA's Geophysical Fluid Dynamics Laboratory, and Conrad Steffen of the University of Colorado's Cooperative Institute for Research in Environmental Sciences.

The report in its entirety is available here: http://www.climatescience.gov/Library/sap/sap3-4/final-report/default.htm.

A USGS press release on the report is available here: http://www.usgs.gov/newsroom/article.asp?ID=2091.

See the U.S. Climate Change Science Program at www.climatescience.gov.

The program, its website says, “integrates federal research on climate and global change, as sponsored by thirteen federal agencies and overseen by the Office of Science and Technology Policy, the Council on Environmental Quality, the National Economic Council and the Office of Management and Budget.”

The IPCC Fourth Assessment Report is here: http://www.ipcc.ch/ipccreports/ar4-syr.htm.



©2009 Jan TenBruggencate