The Antarctic ice sheet is growing mass volume in 2015 according to a recent NASA study published in 2015. Global warming, or climate change, had previously been blamed for a loss in ice volume, and thus it was assumed the melting ice was causing the sea levels to rise. But the researchers claim their findings about the Antarctic ice sheet disagrees with previous global warming reports by the Intergovernmental Panel on Climate Change (IPCC), and ask whether it is possible something else is causing the ocean levels to rise.
In a related report by the Inquisitr, the 2013 IPCC report “concluded that the Antarctic ice sheet has lost an alarming amount of mass with little or no gain.” This is quite a problem since the Antarctic ice sheet contains an estimated 7.2 million cubic miles of ice. If enough ice melted over time, the oceans levels should rise enough to overcome coastal cities all over the world. In the worst case scenario, if the entire Antarctic ice sheet were to melt, then the sea levels would rise by around 200 feet.
In the past, there has been disagreement over this idea. For example, Swedish geologist and physicist Nils-Axel Mörner, former chairman of the INQUA International Commission on Sea Level Change, claimed back in 2009 that the great rise of the sea levels is the “greatest lie ever told.” According to the Telegraph, the scientists believe that if the ocean levels rise this century it will “not be more than 10cm (four inches), with an uncertainty of plus or minus 10cm.”
The global warming IPCC report is actually a middle ground opinion. According to National Geographic, the IPCC predicts the ocean levels will only rise about three feet by the end of the century. This would cause a problem for some coastal cities, although seawalls could be built to mitigate the damage.
A 2015 study from former NASA climate scientist James Hansen could be considered the more extreme view. Hansen and his colleagues argue that an increasing melting of the Greenland and Antarctic ice sheet could cause ocean currents to shut down. If this event occurs, warm waters could become trapped under Antarctica, increasing the rate of the melting ice.
Based upon this Antarctic ice sheet prediction, Hansen claims the ocean levels would rise to about 10 feet from where they currently are in 2015. If this prediction comes true, New York and South Florida would be flooded by the rising waters. Unfortunately, in the case of Florida building sea walls or levees is not an option due to the porous limestone bedrock, meaning that Miami could not be easily saved.
Antarctic Ice Sheet Is Both Growing And Shrinking?
At this point, it would be best to explain the distinction between the Antarctic land ice and sea ice. The Antarctic ice sheet is constantly fluctuating in size due to the sea ice, which forms in salt water during the winter yet melts during the summer. Thus, when scientists talk about gains in the ice sheet, they are focused on Antarctic land ice, which is stored land mass accumulated through snowfall.
The land ice sheets are measured by satellite altimeters and previously it was claimed they were shrinking. Instead, the new 2015 study from NASA reports that the “Antarctic ice sheet showed a net gain of 112 billion tons of ice a year from 1992 to 2001. That net gain slowed to 82 billion tons of ice per year between 2003 and 2008.”
“We’re essentially in agreement with other studies that show an increase in ice discharge in the Antarctic Peninsula and the Thwaites and Pine Island region of West Antarctica,” said Jay Zwally, a glaciologist with NASA Goddard Space Flight Center, according to the NASA press release. “Our main disagreement is for East Antarctica and the interior of West Antarctica – there, we see an ice gain that exceeds the losses in the other areas.”
At the same time, Zwally says the gains in the Antarctic ice sheet mass will be offset by the losses in the Antarctic Peninsula and parts of West Antarctica if they continue to increase in their rate of melting. Assuming this trend occurs, he does not believe “there will be enough snowfall increase to offset these losses.”
Other scientists also point out that these results need to analyzed independently.
“The new study highlights the difficulties of measuring the small changes in ice height happening in East Antarctica,” said Ben Smith, a glaciologist with the University of Washington. “Doing altimetry accurately for very large areas is extraordinarily difficult, and there are measurements of snow accumulation that need to be done independently to understand what’s happening in these places.”
NASA is currently working on a new system to more accurately measure the Antarctic ice sheet changes. Called the ICESat-2, it is claimed that in 2018, it will be able to “measure changes in the ice sheet within the thickness of a No. 2 pencil.”
Arctic Ice Extent Growing Slightly
Back in 2007, Zwally was known for making a prediction about the Arctic ice extent shrinking.
“At this rate, the Arctic Ocean could be nearly ice-free at the end of the summer by 2012, much sooner than previous predictions,” he said.
The scientist was mostly right since the overall thickness and area covered were both down about 50 percent in 2012 in comparison to the measurements made during the 1980’s.
Zwally believes there is an overall downward trend, although in 2015 the Arctic ice’s growth has been a recent spike.
Global Warming And The Rising Sea Level
The most interesting claim made by Zwally is that the melting of the Antarctic ice sheet is not responsible for the sea level rising.
“The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimeters per year away,” Zwally said. “But this is also bad news. If the 0.27 millimeters per year of sea level rise attributed to Antarctica in the IPCC report is not really coming from Antarctica, there must be some other contribution to sea level rise that is not accounted for.”
The NASA press release does not speculate on what this other contributing factor could be. It could be possible the climate model predictions of catastrophic accelerating sea level increases are wildly wrong, or it could be that further study will shed more light on the issue and prove them right. It is also possible there is something else contributing to the thermal expansion of the water, which may lead to even more interesting scientific theories.
Regardless, Zwally knew that critics of climate change science may consider this evidence that proves global warming wrong, but he says that is not the case.
“I know some of the climate deniers will jump on this, and say this means we don’t have to worry as much as some people have been making out,” he said, according to Nature. “It should not take away from the concern about climate warming.”
What do you think?
[Image via NASA]