Gigantic hole two-thirds the size of Manhattan discovered in Antarctic glacier,January 31, 2019
(CNN) A massive cavity two-thirds the size of Manhattan has been discovered growing in an Antarctic glacier, signaling rapid ice decay that has shocked scientists.
A stunning new study on Antarctic sea ice collapse greatly raises the risk of a 10-foot sea level rise this century if President Donald Trump’s climate policies aren’t quickly reversed.
Warming ocean waters drove a 6-fold increase in annual ice mass loss from the Antarctic ice sheet between 1979 and 2017, according to a new study in the Proceedings of the National Academy of Sciences.
It’s been known for a while that the West Antarctic Ice Sheet (WAIS) was unstable and collapsing at an accelerating rate due to global warming. But the new study finds that parts of the vastly larger East Antarctic Ice Sheet (EAIS) are also disintegrating.
While the WAIS contains enough ice to raise sea levels some 20 feet, the EAIS contains enough ice to ultimately raise sea levels 170 feet. Although a complete melting of the Antarctic ice sheet will take many centuries, the new study suggests devastating sea level rise in this century
East Antarctica’s melting “increases the risk of multiple meter (more than 10 feet) sea level rise over the next century or so,” lead author Eric Rignot told the AP. Rignot is a senior project scientist at NASA’s Jet Propulsion Laboratory.
And even just half that level of sea rise means the destruction of every major coastal city in the nation and the world. With just 6 feet of sea level rise, for instance, the southern tip of Florida would be underwater.
This four-decade speed up in ice loss is being driven by global warming. As the study notes, “During the entire period, the mass loss concentrated in areas closest to warm, salty, subsurface, circumpolar deep water (CDW).”
So the greatest sea ice loss is precisely where the deep water surrounding Antarctica is warming up the most.
The amount of sea ice loss — and the rate of speed up — is staggering. “Between 1979 and 1990, Antarctica shed an average of 40 gigatons of ice mass annually. (A gigaton is 1 billion tons.),” the news release explains. But “from 2009 to 2017, about 252 gigatons per year were lost” — a six-fold increase.
The study warns that sea level rise (SLR) will continue to speed up as the ocean continues to warm. And as ThinkProgress reported last week, a different study concluded “ocean warming is accelerating.”
The latest findings suggest that more and more of the EAIS could get exposed to warming ocean water — “and could contribute multimeter SLR with unabated climate warming.”
Tragically “unabated climate warming” is the primary policy of the Trump administration.
The Trump team has worked tirelessly to gut domestic US climate regulations while becoming the only major country to start the process of withdrawing from the 2015 Paris Climate Accord. So, as the study’s findings warn, the time to save our coastal cities is running out rapidly.
But averting that unimaginable catastrophe will require going far beyond reversing Trump’s policies. The world will also have to take global carbon dioxide emissions to near zero by early in the second half of the century.
Also by Joe Romm, Jan 2019: The rate of warming for the upper 2,000 meters of ocean has increased by more than 50% since 1991.
Last year was very likely the hottest year on record, according to the authors of a new study in the journal Science.
The study examined “multiple lines of evidence from four independent groups” measuring ocean heat and concluded “ocean warming is accelerating.” Researchers found the rate of warming for the upper 2,000 meters of ocean has increased by more than 50 percent since 1991.
As a result, “2018 is shaping up to be the hottest for the oceans as a whole, and therefore for the Earth,” a press release accompanying the study explains.
“Global warming is here, and has major consequences already,” it adds, bluntly. “There is no doubt, none!”
The speed up of ocean warming can be seen in the chart below, provided to ThinkProgress by the study’s lead author, Dr. Lijing Cheng of the Institute of Atmospheric Physics (IAP), Chinese Academy of Sciences.
The measurement of ocean heat content (OHC) has gotten much more accurate in recent years, something the authors were able to take advantage of.
“For over a decade, more than 3,000 floats have provided near-global data coverage for the upper 2,000 meters of the ocean,” the study explains. This new Argo system of floating measurement devices provides “superior observational coverage and reduced uncertainties compared to earlier times.”
These high-quality Argo observations combined with other independent, older ways of measuring OHC, have enabled the authors to provide “the context of the record-breaking recent observations to be properly established.”
Often, most people think of global warming as solely about surface air temperatures. But, as the authors point out, there are two reasons ocean heat content are a much better measure of actual global warming than surface air temperatures, which have traditionally been used to determine what years are the hottest on record.
First, as the study states, the oceans take up “about 93 percent of the Earth’s energy imbalance created by increasing heat-trapping gases in the atmosphere from human activities.” So the overwhelming majority of warming ends up in the oceans.
Second, “ocean heat content is not bothered much by weather fluctuations that do, however, affect the surface temperatures.” And OHC is only “somewhat affected by El Niño events,” which can have a big, short-term impact on surface temperatures.
All of this makes ocean heat content a truer and more stable measure of how fast the Earth is warming under climate change.
Thus, when the data show that 2018 has set the record for ocean heat content, that tells us 2018 sets the record for hottest year.
As co-author Kevin Trenberth, a distinguished senior scientist in the Climate Analysis Section at the National Center for Atmospheric Research, told ThinkProgress, “global warming is close to ocean warming and 2018 will be the warmest year on record, followed by 2017.”
Trenberth, a leading expert on the connection between climate change and extreme weather, pointed out that “one of the warmest spots was where Hurricane Florence developed this past year [in the Atlantic] and where Hurricane Harvey developed the previous year [in the Gulf]. The warm water fuels the evaporation and moisture for storms.”
It is “too late to stop ocean warming in this century because ocean response” is so slow, warned Cheng. Water stores a lot a heat, so its temperature fluctuates much more gradually. But, she said, we can slow the rate of warming if we “act as soon as possible to reduce carbon emission.”
As Cheng’s chart shows, ocean heat content is very strongly linked to global CO2 levels. Unfortunately, CO2 levels (or concentrations) won’t stop rising until the world reduces annual global CO2 emissions to near zero, which is in fact the ultimate goal of the December 2015 Paris climate accord.
But we are a long way from releasing zero emissions.
“While there still is time to do something to slow this process down, it is too late to stop serious global warming,” study co-author John Abraham, a professor of thermal sciences at the University of St. Thomas in Minnesota, told ThinkProgress,
Abraham warned that global warming “is happening faster than we previously thought.”
“We are also seeing the impacts, from superstorm hurricanes and typhoons, to drought and deadly wildfires,” he continued. “We are paying the consequences for ignoring the science for decades. What a terrible legacy the denialists have left us and our children.”