Hurricane Sandy was not an aberration. It was New York City's first taste of a trend that could continue for centuries — the storm surge that flooded the city's coastal areas could become a much more frequent — and destructive — occurrence.
Land ice at both of the planet's poles is melting, causing our oceans to rise. But Antarctica, known as the sleeping giant of sea level rise, is melting faster than scientists previously thought.
In a bit of cruel irony, as Antarctica's ice falls into the ocean, the distribution of sea level changes could actually hit the world's largest cumulative contributor to climate change — the United States — harder than elsewhere.
The New York City Panel on Climate Change recently said that sea level rise in the five boroughs won't be the two to four feet that it had previously estimated, but possibly as much as six feet. Cities like Washington DC, Norfolk, Miami, and Seattle could also be hard hit by sea level rise, inundating costal infrastructure and even potentially forcing the relocation inland of tens of millions of inhabitants.
"Sea level rise gives climate change an address, because it is the climate impact we can talk about at the address level," Benjamin Strauss, Vice President for Sea Level and Climate Impacts at the independent science and journalism organization Climate Central, told VICE News. "You can literally walk down a street and give different sea level risk assessments for different properties."
One of the big question marks surrounding how much sea levels will rise in the coming decades comes down to the extent of melting in Antarctica.
Last May, Eric Rignot of NASA's Jet Propulsion Laboratory and the University of California Irvine, along with a team of other scientists, found that a section of the West Antarctic ice sheet around the Amundsen Sea had entered a state of irreversible retreat and could cause over one meter of global sea level rise, or about 4 feet.
"The collapse of this sector of West Antarctica appears to be unstoppable," he said. "The fact that the retreat is happening simultaneously over a large sector suggests it was triggered by a common cause, such as an increase in the amount of ocean heat beneath the floating sections of the glaciers. At this point, the end of this sector appears to be inevitable."
Rignot and his team looked at four decades of observations over which the melt flow of West Antarctica's glaciers steadily increased. He describes the changes to Antarctica's ice sheets as "staggering."
In 1997, Rignot recognized rapid fluctuations of one glacier in the Amundsen Sea sector of West Antarctica, a place called Pine Island. By 2008, he says, the changes had become unlike anything he had ever seen, became so apparent that he realized it was not just a hiccup in the system — it was something much more significant.
Rignot and his team collected a large volume of data in the Amundsen Sea sector between 2009 and 2012 and the following year concluded that the glaciers were retreating into territories without any hills or bumps to block them from melting into the sea.
"The signal was so large, so persistent," he says, "that it could not be discounted or ignored."
Rignot says the most worrisome glacier in the Amundsen Sea sector is Thwaites, a glacier similar in size to Cambodia, not confined to a valley, and which reaches the deepest part of West Antarctica. In Rignot's opinion, Thwaites has already entered a stage of advanced retreat.
"The glaciers in this sector are going now, they started to do so in the 1980s, and have passed the point of no return," Rignot told VICE News.
The disappearance of glaciers in the Amundsen Sea sector, a small fraction of the ice sheet, could trigger the collapse of the entire West Antarctic ice sheet, which could raise global sea levels by up to five meters — or about 15 feet.
Such an event could severely submerge the world's heavily populated coastal areas, and force us to redraw the world map as we know it.
"Antarctica is remote yet relevant to everyone everywhere," Rignot told VICE News. "Sea level rise is global. The consequences are global. The process is operating with tremendous inertia, there is no red button to stop it, we can only, perhaps, slow it down."
The largest uncertainty surrounding the retreat of the West Antarctic Ice Sheet is the rate at which it's glaciers will melt. Rignot says it could be as rapid as one century.
"I think of it like a pile of ice cubes in a warm room," said Climate Central's Strauss. "We know the pile will melt, even if it's difficult to say how quickly."
For the world's largest cumulative greenhouse gas emitter, however, Antarctic melting could have particularly dire consequences.
In a paper published this past December, Ted Scambos, Senior Research Scientist at the National Snow and Ice Data Center, and John Abraham of the University of St. Thomas in St. Paul, Minnesota found that melting in Antarctica will have an "amplified impact" on North America, as well as Europe.
"As Antarctica's total ice mass decrease…, the local gravitational attraction with the ocean decreases. Sea level actually decreases near the continent, at the expense of greater increase in all other parts of the global ocean," they say. "The resulting net change leads to a distribution of sea-level increases that is far more serious for the North American coastline than for most of the southern hemisphere."
Strauss likens the growing chorus of scientific concern over the rate of melting in Antarctica to a hurricane warning. Every hour that we have to better prepare for the arrival of the storm — or rising sea levels — means a greater likelihood of avoiding loss of life and property.
"The same thing is true for sea level rise projections, except that we are going to need decades, not hours or days, to prepare." Strauss told VICE News. "And unlike a hurricane blowing over, the rising sea does not go back down."
Follow Abby Ellis on Twitter: @abbyc_ellis
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