But, according to Gavin Schmidt, a climatologist who is the director of NASA's Goddard Institute for Space Studies, that doesn't mean much when put in the bigger context of global warming.

"These are interesting but they are minor issues," Schmidt said of the plumes. "People have detected methane seeps all over the place off the continental shelves and mostly they are in equilibrium with what is going on. So if the water is warm, you will get a little bit more or a little bit less … The overall constraints are such that it's really hard to see how in the present climate situation how it could be a big effect."

Related: A Massive Amount of Death Is Plaguing the World's Oceans

But Kevin Schaefer, a research scientist with the National Snow and Ice Data Center who studies emissions from permafrost, was not as dismissive. The challenge, he said, was that so little is known about these methane plumes including just how much is being released on a global scale.

"It's a potential risk but I'm not sure the scientific community has a good estimate of how much this might be in the future," he said. "We don't know. It could have an impact. Whether it's radical, I would probably say not."

The total area includes 1,185–1,825 municipalities where land that is home to more than half of the current population would be affected, among them at least 21 cities exceeding 100,000 residents. Under aggressive carbon cuts, more than half of these municipalities would avoid this commitment if the West Antarctic Ice Sheet remains stable. Similarly, more than half of the US population-weighted area under threat could be spared. We provide lists of implicated cities and state populations for different emissions scenarios and with and without a certain collapse of the West Antarctic Ice Sheet. Although past anthropogenic emissions already have caused sea-level commitment that will force coastal cities to adapt, future emissions will determine which areas we can continue to occupy or may have to abandon.

Testing Theories of American Politics: Elites, Interest Groups, and Average Citizens
Martin Gilens and Benjamin I. Page

What do our findings say about democracy in America? They certainly constitute troubling news for advocates of “populistic” democracy, who want governments to respond primarily or exclusively to the policy preferences of their citizens. In the United States, our findings indicate, the majority does not rule — at least not in the causal sense of actually determining policy outcomes. When a majority of citizens disagrees with economic elites or with organized interests, they generally lose. Moreover, because of the strong status quo bias built into the U.S. political system, even when fairly large majorities of Americans favor policy change, they generally do not get it.

What do our findings say about democracy in America? They certainly constitute troubling news for advocates of “populistic” democracy, who want governments to respond primarily or exclusively to the policy preferences of their citizens. In the United States, our findings indicate, the majority does not rule — at least not in the causal sense of actually determining policy outcomes. When a majority of citizens disagrees with economic elites or with organized interests, they generally lose. Moreover, because of the strong status quo bias built into the U.S. political system, even when fairly large majorities of Americans favor policy change, they generally do not get it.