Methane discovery advances sea level rise estimates

A new disclosure of methane gas released by thawing permafrost represents something more for coastal residents to worry about.

A Florida State University professor says  ancient reserves of methane gas seeping from the melting Arctic ice cap are a powerful greenhouse gas that causes climate warming.

The university reports that until recently, the frozen soil and ice served to plug or block these vents. But thawing conditions have allowed the conduits to open, and deep geologic methane now escapes, the university said.

The head of the four-member research team is  Jeff Chanton. Because he is located in Florida, the bulk of his concern is directed there. He says the methane will expedite the rise in ocean levels. In their studies of Alaska and Greenland, the team found  77 previously undocumented methane seep sites, comprising 150,000 vents to the atmosphere. They used air photos.

People who live in coastal areas in Florida could be directly affected, said Chanton, who analyzed the methane and dated it to more than 40,000 years old, according to a university release. All this seeping methane causes more melting ice, Chanton said, which causes sea levels to rise and could affect coastal real estate values — sooner rather than later, possibly over the next 50 to 100 years, Chanton said.

“Along the flat Florida coastline, a 1-foot rise in sea level could cause anywhere from 10 to 100 feet of shoreline retreat — erosion,” the university quoted Chanton as saying. “For us here in Florida, this is really important because we can expect the coast to recede.”

The study has relevance to coastal Costa Rica where researchers already has estimated the impact of varying amounts of sea level rise.

Until now most of the concern has been directed at the release of carbon dioxide, a component of what is called greenhouse gas. The sea is rising at about 3 millimeters a year now.

Another recent study said that predictions of sea level rise advanced in 2007 by the  Intergovernmental Panel on Climate Change did not account for some factors. The Intergovernmental panel predicted sea level rise by 2100 to be 20 to 60 centimeters, about 8 to 24 inches. Instead, this current study predicts an increase in sea level of between 60 and 180 centimeters or from two to six feet. And that is without considering methane.

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