Ever since a trillion-tonne iceberg broke away from Antarctica last week, there has been much debate about whether it’s related to climate change or not. While some say no and attribute it to different factors, others believe it is eventually linked to climate change and its impact on Earth.
For the record, an iceberg the size of Delaware in US broke off an Antarctic ice shelf. Named the A68, it represents more than 12% of the Larsen C ice shelf, a sliver on the Antarctic Peninsula.
Antarctica is surrounded by ice shelves, floating extensions of glaciers that exist over land. These extensions break away at times and it’s a natural process. Last week’s event produced an iceberg 2,200sq miles in extent, while a larger portion of Larsen C had broken off in 1986.
As scientists try to figure what made the chunk to break off, much speculation is already under way. “I think we’re all scratching our heads as to just what combination of changes in the ice, air and ocean caused this,” said Ted Scambos, senior research scientist at the National Snow and Ice Data Centre, as reported on WGN-TV. A central theme of the ongoing debate is whether it can be attributed to global climate change.
One researcher said no one can be certain what caused iceberg A68 to break off, or at least yet; it’s far too cold in the Antarctic winter to fly in a crack research team. “We may have to wait until November, when the southern hemisphere waxes toward summer and it becomes safe to fly airplanes over Antarctica again,” Martin O’Leary, a glaciologist with Swansea University and the Antarctic research programme Project Midas, was quoted as saying in Business Insider.
Some scientists say this particular calving won’t raise sea levels, since the ice was already floating in the water – the effect is similar to why melting ice cubes in a drink don’t overflow a glass. They call it ‘natural event’, for ice shelves have been cracking off huge icebergs for eons.
But others feel this perspective is akin to looking at the situation “through a microscope” instead of acknowledging the bigger picture of human-driven global warming and climate change. “To me, it’s an unequivocal signature of the impact of climate change on Larsen C,” Eric Rignot, a glaciologist at Nasa’s Jet Propulsion Laboratory and the University of California, Irvine, told CNN. “This is not a natural cycle. This is the response of the system to a warmer climate from the top and from the bottom. Nothing else can cause this.”
Rignot said colleagues who say otherwise are burying their heads “in the ice”.
Similarly, Kevin Trenberth, a senior scientist at the US National Centre for Atmospheric Research, said “They’re looking at it through a microscope” rather than seeing macro trends, including the fact that oceans around Antarctica are warming, helping thin the ice.
The difference in opinion stems partly from a perceived lack of data. Some scientists say they don’t have the super-long-term datasets they would need to prove that man-made warming affected this particular ice sheet.
At the same time, they can’t dismiss global warming’s contribution, either.
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