In what may prove to be a turning point for political action on climate change, a breathtaking new study casts extreme doubt about the near-term stability of global sea levels.
The study—written by James Hansen, NASA’s former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields—concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. Hansen acknowledges that his study implies change far beyond previous consensus estimates. He said he hoped the new findings would be “substantially more persuasive than anything previously published.”
To come to their findings, the authors used a mixture of paleoclimate records, computer models, and observations of current rates of sea level rise, but “the real world is moving somewhat faster than the model,” Hansen said.
The entire study has just been made available here.
The study postulates that this faster sea level rise, brought on by the melting of parts of Antarctica and Greenland, could lead to a number of climate change “feedbacks” that could shut down the oceans’ circulation; stratify the polar seas with warmer waters trapped below cold surface layers; increase the temperature difference between low and high latitudes; and generate stronger storms.
Hansen’s study does not attempt to predict the precise timing of the feedback loop, only that it is “likely” to occur this century. In the study’s likely scenario, New York City—and every other coastal city on the planet—may only have a few more decades of habitability left. That probability, in Hansen’s view, requires “emergency cooperation among nations.”
Hansen said, “We conclude that continued high emissions will make multi-meter sea level rise practically unavoidable and likely to occur this century. Social disruption and economic consequences of such large sea level rise could be devastating. It is not difficult to imagine that conflicts arising from forced migrations and economic collapse might make the planet ungovernable, threatening the fabric of civilization.”
One of the study’s co-authors is Eric Rignot, whose own study last year found that glacial melt from West Antarctica now appears to be “unstoppable.” Chris Mooney, writing for Mother Jones, called that study a “holy shit” moment for the climate.
In 2013, Hansen left his post at NASA to become a climate activist because, in his words, “as a government employee, you can’t testify against the government.” In the new study, Hansen writes, “there is no morally defensible excuse to delay phase-out of fossil fuel emissions as rapidly as possible.”