Several media outlets reported Wednesday that an enormous iceberg the size of Delaware had broken off an ice shelf in Antarctica. Politicians, journalists and others quickly associated the news with climate change.
Political commentator David Sirota tweeted that the world had reached a “stage of apocalyptic climate change.” Democratic Sen. Ed Markey called the iceberg “monumentally alarming” in a statement. The United Nations Climate Action twitter account shared the story with the hashtag “#climatechange.”
Verdict: Unsubstantiated
Leading experts have found no direct evidence to link the event to climate change, although some within the field disagree. While many experts describe the iceberg formation as a natural occurrence, many do believe climate change caused the partial collapse of Antarctic ice shelves in recent history.
Fact Check:
Scientists have monitored a rift at the Larsen ice shelf in Antarctica for years. When researchers confirmed Wednesday that a massive iceberg had formed, some in the media and elsewhere reflexively attributed the event to climate change.
But several climate scientists have pushed back against the notion that climate change caused the iceberg to form. “We’ve been surprised by the level of interest in what may simply be a rare but natural occurrence,” Adrian Luckman, glaciology professor at Swansea University, wrote in an article.
Icebergs may form as part of a regular process known as calving, which occurs on stable ice shelves every few decades.
“The calving of icebergs from ice shelves is a natural occurrence, and it is too early to link this event to human-induced climate change because there is no direct evidence to do so,” Luckman told The Daily Caller News Foundation.
While climate change may not be the culprit in this case, scientists generally have attributed other events on the Larsen ice shelf to climate change.
“Climate warming in the Peninsula is well documented since the 1950s,” Eric Rignot, a glaciologist at NASA and the University of California-Irvine, told TheDCNF. “It has been warming faster than the rest of Antarctica.”
The Antarctic Peninsula is one of several spots around the world where scientists have observed rapid warming. Periods of rapid warming and cooling have occurred in the peninsula over the last 1,000 years, and although the region has warmed in recent decades, research suggests the temperatures are within the natural variability of the region. The peninsula may even be experiencing a cooling period.
Experts believe warmer temperatures caused melt ponds to seep into and weaken Larsen B, a part of the ice shelf that collapsed in 2002. But scientists didn’t observe the same phenomena on Larsen C, where the new iceberg formed.
“Larsen C did not demonstrate the same melt pond pattern of Larsen B, so it’s not as easy for us to quickly attribute this to similar mechanisms,” Kelly Brunt, glaciologist for the NASA Goddard Space Flight Center, told TheDCNF.
Yet some experts believe there’s still a link to climate change. “Over a period of sustained warming, the Larsen C Ice Shelf has only lost area over the years and is now at its most retreated position,” said Luckman. “This circumstantial evidence is enough to convince many that climate change has played a part in the rift and calving from Larsen C.”
Rignot is one of those scientists. “I do not quite understand colleagues who are on the fence to attribute this massive retreat to climate change,” he said. “This is not part of a natural cycle.”
He notes how the ice front has receded 60 kilometers since the 1980s. And according to Rignot, elevation measurements suggest the ice shelf may have thinned by 40 meters over the last 20 years. “The most likely reason for Larsen C to break that far back is that it got thinner over time,” said Rignot. “A thinner ice shelf is more likely to crack.”
He believes Larsen C will eventually collapse. “Larsen C is next. Not just yet, but this calving marks the beginning of its retreat.”
There is genuine disagreement among experts over the causes of the rift. “I very much respect his position,” said Luckman. “A thinner ice shelf, however, is not necessarily more likely to crack because the nature of stresses in ice, and the process of fracture is complex.”
Whether or not the iceberg formed due to climate change, experts do not believe the calving of icebergs in the region contributes meaningfully to sea-level rise. But they are concerned about changes to the peninsula.
“The situation is a conundrum,” Helen Fricker, professor at the Scripps Institution of Oceanography, wrote in a recent article. “We want people to be aware of Antarctica and concerned about what might happen there in the near future as climate changes. But hyping research results to sound like climate change, when they are just improved understanding of natural behaviour, is misleading.”
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