Definitive study highlights polar ice melt
The melting of polar ice caps raised sea levels by nearly half an
inch (11 millimeters) over the last two decades, scientists said
Thursday, calling it the most definitive measure yet of the impact of
climate change.
There have been more than 30 previous estimates of whether and how
much the ice caps are shrinking. But the numbers were often vague, with
wide ranges, and different studies sometimes contradicted each other,
the researchers said.
The new study in the US journal “Science,” combines data from ten
different satellites since 1992, carefully matching up time periods and
geographical locations so as to make a more accurate and wider-ranging
assessment.
“Changes in the mass of ice stored within the polar ice sheets are
important because they’re a measure of changes in global climate and
they directly affect global sea levels,” said lead researcher Andrew
Shepherd from the University of Leeds, in England.
Using the combined data, the international team of 47 scientists was
able to determine that Antarctica and Greenland and have contributed to
just over 11 millimeters of sea level rise since 1992, or a fifth of the
total. “Crucially this improved certainty allows us to say that both
have been losing ice,” Shepherd told reporters during a telephone
conference call on Wednesday.
Indeed, according to their analysis, Greenland is losing ice faster
than before, added co-author Erik Ivins of NASA’s Jet Propulsion
Laboratory.
“If we compare data from the 1990s to those over the last decade, it
would appear as though Greenland is losing mass at about five times the
rate today as it was in the early 1990s,” he explained.
Additionally, the new analysis showed that ice in Antarctica is
shrinking overall, but more slowly than some reports have suggested.
“West Antarctica is losing quite a bit of mass,” Ivins explained,
though he noted that there is some compensation going on by gain in east
Antarctica.
The researchers called their study a snapshot of the past twenty
years, saying it can serve to increase understanding of what has already
happened but does not provide predictions of what is yet to come.
Co-researcher Ian Joughin added that “the study demonstrates we need
to not just make snapshots but sustained measurements, through a
coordinated effort,” over the next 20 years.
A separate study Wednesday reported that sea levels are rising 60
percent faster than the UN’s climate panel forecast in its most recent
assessment. A trio of specialists reported in the journal “Environmental
Research Letters” that sea levels are increasing at an average of 3.2
millimeters (0.125 inch) per year, compared to the 2 mm (0.078 inch)
predicted by the UN’s Intergovernmental Panel on Climate Change.
In addition to the melting of polar ice caps, sea levels are rising
because warmer temperatures causes water to expand.
AFP |