A recent NASA study shows that the Antarctic ice sheet is gaining more ice than it is losing, contradicting a 2013 report by the Intergovernmental Panel on Climate Change (IPCC) and prompting scientists to reconsider climate change hypotheses.
In a statement announcing the study, which was published in the Journal of Glaciology last week, NASA explained that according to the new findings, the Antarctic ice sheet saw net gains of 112 billion tons of ice per year from 1992 to 2001. The ice sheet also gained ice yearly from 2003 until 2008, albeit at the slower pace of 82 billion tons of per annum.
According to Zwally, the findings are not completely opposed to earlier evaluations of Atlantic ice sheet loss. “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,” he said, adding “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.”
The gains are a result of ancient snowfall. From the study:
The thickening is likely a result of the marked increase in accumulation that began in the early Holocene, ~10 ka years ago… A residual thickening from the Holocene increase in accumulation is consistent with the characteristically slow response time of the ice flow to accumulation changes in [East Antarctica].
Glaciologist Ben Smith, who was not involved in the study, said the new finding "highlights the difficulties of measuring the small changes in ice height happening in East Antarctica." He added that measuring the altitude, or altimetry, correctly "for very large areas is extraordinarily difficult." Zwally and his team analyzed information gathered by NASA satellites to reach their conclusion.
Zwally estimated that ice losses in this part of the Antarctic will be equal to the gains in about 20 or 30 years, however.
The new analysis raises a new question — why our our seas rising? In Zwally's words, "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."
Danielle Wiener-Bronner is a news reporter.