Glaciologist says carbon emissions to date will cause 69 foot sea level rise

By Chris Mooney / Mother Jones

Last week, a much-discussed new paper in the journal Nature seemed to suggest to some that we needn’t worry too much about the melting of Greenland, the mile-thick mass of ice at the top of the globe. The research found that the Greenland ice sheet seems to have survived a previous warm period in Earth’s history—the Eemian period, some 126,000 years ago—without vanishing (although it did melt considerably).

But Ohio State University glaciologist Jason Box isn’t buying it.

At Monday’s Climate Desk Live briefing in Washington, DC, Box, who has visited Greenland 23 times to track its changing climate, explained that we’ve already pushed atmospheric carbon dioxide 40 percent beyond Eemian levels. What’s more, levels of atmospheric methane are a dramatic 240 percent higher—both with no signs of stopping. “There is no analogue for that in the ice record,” Box said.

And that’s not all. The present mass scale human burning of trees and vegetation for clearing land and building fires, plus our pumping of aerosols into the atmosphere from human pollution, weren’t happening during the Eemian. These human activities are darkening Greenland’s icy surface, and weakening its ability to bounce incoming sunlight back away from the planet. Instead, more light is absorbed, leading to more melting, in a classic feedback process that is hard to slow down.

“These giants are awake,” said Box of Greenland’s rumbling glaciers, “and they seem to have a bit of a hangover.”

To make matters worse, there’s also Antarctica, the other great planetary ice sheet, which contains 10 times as much total water as Greenland—much of which could also someday be translated into rising sea level. While Greenland is currently contributing twice as much water to sea level rise as Antarctica, that situation could change in the future. It’s kind of as though we’re in a situation of “ice sheet roulette” right now, wondering which one of the big ones will go first.

Box also provided a large-scale perspective on how much sea level rise humanity has already probably set in motion from the burning of fossil fuels. The answer is staggering: 69 feet, including water from both Greenland and Antarctica, as well as other glaciers based on land from around the world.

Read more from Mother Jones: http://www.motherjones.com/environment/2013/01/climate-desk-greenland-and-69-feet-sea-level-rise

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