Science #WhoaScience

Yes, A 1,000-Foot Thick, Delaware-Sized Piece Of Antarctica Could Break Off Within Weeks

, Opinions expressed by Forbes Contributors are their own.

In recent years there have been some odd claims counter to prevailing observations and peer-review literature about the relationship between climate change and the polar regions.  Most of those have been thoroughly addressed or debunked by other scientists. Professor William Chapman at the University of Illinois had one of the more thorough rebuttals. The polar regions continue to be some of the "first responders" to warming climate. In recent weeks, scientists have warned that a "block" of ice about the size of a U.S. state may soon break away from Antarctica. By the way, "soon" means in the next few days or weeks according to what Dan McGrath of the United States Geological Survey told Reuters. I honestly feel silly referring to an iceberg that is about 1,000 ft thick and nearly the size of Delaware as a "block," but you get the point.

NASA Earth Observatory

Crack in the Larsen C Ice Shelf.

The rift in the Larsen C Ice Shelf was observed with great detail during late summer-fall 2016 NASA IceBridge campaign. Icebridge is a mission designed to use airborne instruments to monitor and survey Earth's polar regions over a six year period. It will "bridge" the gap in polar observations between the Ice, Cloud and land Elevation Satellite (ICESat) and ICESat-2  (planned for launch within the next couple of years). These satellite missions are critical for monitoring Earth's vital signs and must be maintained. Dr. Thomas Wagner is NASA's program scientist for cryosphere and the ICESat 2/IceBridge missions. He points out

Ice shelves buttress glaciers around Antarctica. Their break up causes the rapid flow of glacial ice into the sea. This process is considered the number one potential trigger of rapid sea level rise. While Larsen C itself is not a potential trigger, it is a natural laboratory to study ice shelf break up and implications for other areas.

NASA's Earth Observatory website builds on Wagner's description of the natural cracking and calving of ice from the front of an ice shelf

Shelves are fed by glaciers and ice streams coming from the interior of the continent. They advance into the ocean until a calving event takes place. The shelf front retreats and then advances again. The whole cycle can occur over the span of a few decades.......But calving that happens faster than a shelf can re-advance can mean trouble for an ice shelf.

Dr. Kelly Brunt of the Earth System Science Interdisciplinary Center (ESSIC) at University of Maryland also emphasized by email that iceberg calving events are normal and part of the ‘balance' of ice sheets (snow coming in has to be balanced by ice going out). She goes on to say

this is a large calving event and will result in an ice shelf that is very different from an ‘average' Larsen C (based on size and location of the ice-shelf calving front) so a calving event like this is probably meaningful and important to watch;

Initially, there was some question about whether Larsen C would suffer the same fate as Larsen B, which broke apart in 2002, but the latest observations suggest that it will and that it is imminent. Because ice shelves float they are not direct contributors to sea level rise. However Wagner's point conveys that if a shelf ultimately disintegrates, glaciers can make their way to the sea (and that process does increase sea level).


Break-up of the Larsen B Ice Shelf over a decade ago.

In a recent blog, two Swansea University scientists, Adrian Luckman and Martin O'Leary, seemed to sound the alarm on Larsen C. They wrote on May 31,


They note that when the calving happens, the ice shelf will shed about 10% of its area and alter the physical attributes of the Antarctic Peninsula. In the journal, The Cryosphere, a recent study noted that the rift and calving could significantly destabilize the ice shelf, which is significantly larger than the Larsen A/B shelves (see below). One particularly cool 'aside; is that it is currently dark in Antarctica as winter approaches in the Southern Hemisphere. Project MIDAS scientists are monitoring the crack with spaceborne synthetic aperture radar (SAR) interferometry  (Sentinel-1) rather than visual observations.

NASA and Dr. Chris Shuman

Area losses in the Northern Antarctic Peninsula. Source: NASA/C. Shuman

Dr. Chris Shuman, a former colleague of mine at NASA Goddard Space Flight Center, studies Antarctica and its ice shelves. He told me in an email

both the Larsen A and Larsen B had 'early losses' in the late 1980s and mid 1990s, respectively. This may have led to further instability and the collapse events in subsequent years during a relatively warm phase for the overall Peninsula. The Larsen C rift, on the other hand, appears to be separating its ~5000 km2 berg (~77% the size of Delaware) during a period of slight cooling relative to previous decades.

Oooooh boy, did he say 'slight cooling' period. Some skeptics will want to misuse that statement so let me place it in context because research stations have found some of the most aggressive warming on Earth in the Antarctic Peninsula since the 1950s. Shuman referred me to a caveat in the abstract of a recent study published in Nature.


Please resist the urge to mischaracterize that information based on this study when the authors clearly warn that it is 1% of the continent and a truncated period of time. For additional information, Climate Central provides an excellent summary of the broader warming trends in the regio and the aforementioned cool period.

The image below, acquired by the Landsat 8 satellite, is centered on the northern part of Larsen. Remnants of the previous collapses (A and B) are evident. Other features in the image include the remaining shelf (white with rifts evident), fast ice (light blue areas representing sea ice tethered to the shelf or coastline), ocean (dark), and areas of small icebergs.

NASA Earth Observatory

The Larsen Ice Shelf in January 2016. Source: NASA

For now, all climate eyes (or radar "eyes") are on the Larsen C ice shelf.