When James Hansen speaks, climate hawks listen. Hansen was legendary during his long career as NASA’s chief climatologist for being ahead of the curve on seeing the threat of catastrophic climate change. Now he teaches at Columbia University, and he has more bad news to deliver. According to a study conducted by Hansen and 16 coauthors, being published this week in the European Geophysical Union’s open-access journal Atmospheric Chemistry and Physics, the effects of even moderate warming on sea-level rise are worse than previously believed.
Hansen and his colleagues combined analysis of the historical record with modeling and current observation and found that the rate of oceanic ice melting in Greenland and Antarctica may exceed our expectations. As InsideClimate News explains, the scientists “analyzed how an influx of cold freshwater from the planet’s melting ice sheets will disrupt the ocean’s circulation … They concluded the influx of freshwater from melting ice sheets in modern times would essentially shut down the ocean’s circulation, causing cool water to stay in the Earth’s polar regions and equatorial water to warm up even faster.”
“The cooling mechanism is cut off, so it’s melting ice shelves,” Hansen explained in an interview with Grist. “It’s a really dangerous situation where you get melting that causes more melting.”…
The bottom line, as Slate’s Eric Holthaus writes, is 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.” A sea-level rise of 10 feet would inundate parts of major cities from New York to Shanghai…
Hansen, despite his reputation for doomsaying, remains hopeful about the prospects for fending off the worst of climate change. The biggest emitting nations are not pledging to cut emissions enough to even keep warming below 2C, but Hansen says a gradually rising global carbon fee could change that. It could force emissions to drop several percentage points per year and hold us down to 1.5C in warming. To get this outcome from the messy global climate treaty process would be fantastic, but it is highly unlikely. Hansen sort of admits this, but holds out hope nonetheless.
“I don’t think it’s impossible that you could get key players to agree to the concept of an international carbon fee,” he says. “It’s not going to happen with 190 countries sitting around a table. It’s going to happen with key players negotiating directly either at Paris or in the years ahead.” Specifically, Hansen imagines that the world’s two biggest economies and biggest carbon emitters, the U.S. and China, would negotiate a carbon fee bilaterally and then use their global buying power to force all of their trading partners to join.
People who actually read and study agree. At least economists who earn a living in the world of business and finance – as well as academia. I happened to see Peter Orszag on Bloomberg Surveillance, the other morning, and he was working at advancing the Hansen solution as practical and possible. Hoping against hope that reasonable leaders of industrial nations might engage in bilateral negotiations and treaties to force the reduction in atmospheric carbon.
No, he didn’t hold out any hope for the United States offering world leadership unless anti-science conservatives were absent from both houses of Congress and the White House. Poisonally, I don’t think Americans are well-enough informed or yet free enough of medieval hobgoblins to bring about that quality of change.