Sea Levels Could Rise at Least 20 Feet

Even if world manages to limit global warming to 2°C — the target number for current climate negotiations — sea levels may still rise at least 6 meters (20 feet) above their current heights, radically reshaping the world’s coastline and affecting millions in the process.

That finding comes from a new paper published on Thursday in Science that shows how high sea levels rose the last time carbon dioxide levels were this high.

That was about 3 million years ago, when the globe was about 3-5°F warmer on average, the Arctic 14.4°F warmer, megasharks swam the oceans, and sea levels stood at least 20 feet above their current heights.

The megasharks aren’t coming back, but those sea levels could be no matter what happens in December’s climate summit in Paris.

“Even if we meet that 2°C target, in the past with those types of temperatures, we may be committing ourselves to this level of sea level rise in the long term,” Andrea Dutton, a geochemist at the University of Florida and one of the study’s co-authors, said.  “The decisions we make now about where we want to be in 2100 commit us on a pathway where we can’t go back.  Once these ice sheets start to melt, the changes become irreversible.”

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