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Gulf swallowing Galveston faster than thought

By by HARVEY RICE Houston Chronicle
Jan. 5, 2013 at 11 p.m.


GALVESTON - Rising sea levels are likely to cover the coastal highway on the unprotected west end of Galveston sooner than previously predicted.

A 2007 study underwritten by the city of Galveston that anticipated rising sea levels would cover the highway within 60 years appears to have been overly optimistic.

The $50,000 geological hazard report was prepared for the city by geologists from the University of Texas, Rice University and Texas A&M University but then shelved. The report based its calculation on historic sea level rise and failed to include climate change. Sea levels are rising much faster than previous estimates that accounted for climate change, according to reports released in December by U.S. government scientists and in November by the World Bank.

"It's higher than the estimates they gave us five years ago," said Jim Lester, president of the Houston Advanced Research Center, whose scientists are experienced in coastal issues.

Sea-level rise may pose an even graver problem for Galveston than other coastal areas because the island is sinking at a faster rate than most other areas in the country, a condition known as subsidence.

"If you assume subsidence will occur, that means sea-level rise will be even worse than in the rest of the country," said Stephen Gill, senior scientist with the National Oceanic and Aeronautics Administration, or NOAA.

Erosion and loss of protective wetlands are further eating away at the island, said Val Marmillion, managing director of America's Wetland Foundation. The island could shrink by one-third within 30 years, said Marmillion, whose organization based its conclusions on a $4.2 million study by Entergy of sea-level rise threats to the Gulf Coast.

"The barrier islands are in a very serious situation in all the Gulf Coast states," Marmillion said. "Galveston, because it is so heavily populated, may be one of the more vulnerable islands we have."

The World Bank study, "Turn Down the Heat: Why a 4-degree C (Celsius) Warmer World Must be Avoided," found that sea levels rose 0.6 inch each decade for most of the last century, but more than doubled to 1.4 inches per decade beginning in the 1990s. The bank said that glacial and Antarctic ice melt has accelerated in recent years and could add 4.6 feet to sea-level rise by 2100 if the rates persist.

The annual increases are imperceptible and may take decades to inundate populated areas, but sea-level rise increases erosion and property damage from high tides and small storms, as well as major storms, according to a November report by Climate Central, an independent organization that assesses climate science. Every small increase in sea-level rise adds to the threat, said climate scientist Ben Strauss, Climate Central chief operating officer.

"They are a launching pad," Strauss said.

The Climate Central study found that sea-level rise based on the historical record alone increased the odds of flooding on Galveston island by 2030 from a 100-year-flood or greater between 14 and 17 percent. The odds grow to about 20 percent if climate change is taken into account.

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