Saturday, July 15, 2017

San Diego Scientist Says Large Iceberg That Broke From Antarctica May Not Be Cause For Alarm

By David Wagner of KPBS.
"An iceberg the size of Delaware detached from the Larsen C ice shelf in Antarctica earlier this week. But one San Diego scientist said this alone will not lead to significant sea level rise, and we should avoid jumping to the conclusion that global warming was responsible.

Scripps Institution of Oceanography glaciologist Helen Fricker has been studying the massive icebergs that periodically break off of Antarctica since the mid-1980s.

"This is not the largest iceberg we've ever seen come from Antarctica. There are parts of Antarctica that are changing and definitely contributing to sea level. But we shouldn't get too excited about every little crack and every little melt stream that turns up in Antarctica, because some of these processes are natural," she said.

Fricker said to keep in mind that this chunk of ice — though it may seem large — was already floating in the ocean. So, like an ice cube melting in a glass of water without raising the volume contained in the glass, it will not directly cause sea levels to rise.

And though ice shelves can help restrain ice on land from melting into the ocean, this particular iceberg was not holding back very much grounded ice.

As for what caused the iceberg to break off, Fricker said some dramatic events are simply part of a normal process. Over time, snowfall deposits new ice on the Antarctic ice sheet, while other ice eventually cleaves away.

"Cracks develop on ice shelves and icebergs calve off. It's just something that happens. It's part of the natural cycle of the mass gain and mass loss of an ice sheet over decades," she said.

This week's event had been predicted for some time, Fricker said. The detachment was clearly not the result of any warm summer melting, since the southern hemisphere is currently in the middle of winter.
Other scientists have attributed a greater role to climate change. UC Irvine glaciologist Eric Rignot is quoted in a Los Angeles Times story , saying, "This is a proxy for what is looming ahead as climate keeps warming up. This is not a natural cycle. This is a process of disintegration of ice around the Antarctic."

Fricker said climate change can indeed have troubling effects on Antarctic ice. In a recent article for The Guardian, she wrote, "Antarctic ice shelves overall are seeing accelerated thinning, and the ice sheet is losing mass in key sectors of Antarctica. Continuing losses might soon lead to an irreversible decline."

But based on her lab's analysis, this event — taken on its own — does not appear to be cause for alarm.

"The conundrum is, we do want people to be concerned about Antarctica," Fricker said. "But we want them to be concerned about the right things.""

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