A section of the rift in Larsen C ice shelf, photographed from a NASA plane on November 10, 2016. The crack has been expanding rapidly in recent weeks and scientists expect a segment of the shelf larger than Delaware to fall into the Southern Ocean at any time.
Note: The Larsen C ice shelf broke from the Antarctic Peninsula on July 12, 2017. This post was published prior to that split.
This post was updated July 7, 2017, to correct the location of the Larsen C ice shelf.
Any day now on the Antarctic Peninsula, 10 percent of the Larsen C ice shelf will calve off and form one of the biggest icebergs ever recorded on the planet, estimated at 3,100 square miles—almost the size of Delaware and Rhode Island combined. Scientists with Project MIDAS have been tracking a rift on the shelf for the past two years and announced June 28 that the shelf is “unzipping” at an unprecedented rate of 30 feet per day, which is the fastest rate of detachment ever recorded on this ice shelf.
This calving follows the split and subsequent disintegration of the Larsen A and Larsen B ice shelves in 1995 and 2002, respectively. Both of those events threw large icebergs out to sea, forever changing the landscape and decimating habitat for wildlife that depended on these areas of ice to breed and feed. The Larsen B ice shelf existed for more than 10,000 years, and now it is largely gone.
Like all ice shelves, Larsen C floats on top of the water, so the break-off of this iceberg will not contribute to sea level rise. But the shelf acts like a cork in a bottle, keeping glaciers on the continent in place. Once the shelf goes, there is nothing stopping the glaciers from flowing into the ocean, and that does contribute to global sea level rise.
Recent advancements in scientific modeling indicate that the ice sheets covering much of Antarctica could undergo catastrophic melting if the planet continues to warm at its current pace.
While scientists have not directly attributed the Larsen C rift to global warming, they have reported fundamental changes in Antarctica. In late June, the scientific community was stunned to see rainfall on the Ross Sea ice shelf—the entire continent is classified as a desert due to the scant precipitation it receives—along with pooling meltwater covering an area the size of Texas. Melting and refreezing events can make the shelf less stable and more prone to breaking up.
The Southern Ocean is vital to the health of the planet. Melting ice sheets will release so much fresh water into the sea that serious consequences are almost certain, including changes in the currents that carry critical nutrients to the rest of the global ocean.
Even as governments around the world work to limit global temperature rise, the 25 members of the Commission for the Conservation of Marine Living Resources (CCAMLR) should build on recent successes by expanding a network of marine protected areas (MPAs) in the Southern Ocean.
Studies show that protected areas may safeguard carbon stores and that MPAs can build ecosystem resilience to climate change by eliminating stresses such as fishing. CCAMLR pledged in 2009 to create this network and took a huge first step in October 2016 by establishing the Ross Sea Region MPA—the largest marine reserve on the high seas.
A network of MPAs would preserve connectivity among the many unique ecosystems of the Southern Ocean, giving marine life contiguous migration, breeding, and foraging routes across protected areas, and significantly contributing to global ocean protection targets.
The Pew Charitable Trusts is working with our partners in the Antarctic and Southern Ocean Coalition to encourage CCAMLR to create this network by 2020. To take the next steps toward that goal, the commission should designate MPAs in the East Antarctic, the Weddell Sea, and the Antarctic Peninsula. CCAMLR has been discussing the East Antarctic protected area for the past six years and should move swiftly to complete that designation.
A Southern Ocean MPA network would be the first of its kind in the high seas, and would provide long-term protection for millions of penguins, whales, and seals, and for the source of critical nutrients for the world’s ocean.
Adélie penguins head for the icy waters of the Southern Ocean to forage.
© John B. Weller
A story in the July issue of National Geographic showcases the remarkably diverse life beneath the ice at Dumont d’Urville, the French scientific base on the Adélie Coast of East Antarctica. Yet, at the same time, a soon to be published study by Pew marine fellow Yan Ropert-Coudert reveals the tragic changes taking place in the region: Several large colonies of Adélie penguins suffered 100 percent chick mortality during two recent breeding seasons, which Ropert-Coudert attributes to the changing climate. Within the East Antarctic MPA, CCAMLR should create a strict no-take marine reserve in this Dumont d’Urville area to help mitigate the climate impacts and give penguins a chance to adapt to their changing environment without other outside pressures, like fishing, adding more stress.
Successfully implementing the CCAMLR network of MPAs would help mitigate climate impacts like the Larsen ice shelf collapse and would serve as a shining example of international cooperation for a better future for Antarctic wildlife and all who rely on a healthy global ocean.
Andrea Kavanagh directs The Pew Charitable Trusts’ global penguin conservation program.