Despite Global Warming, Antarctica Ice Shelves Exhibit Growth for the Past 20 Years

Dr. Frazer Christie of the Scott Polar Research Institute (SPRI) in Cambridge spearheads a research team studying the growth of some Antarctic ice shelves over the past two decades.

Ice Shelf

The National Snow & Ice Data Center (NSIDC) defines ice shelves as permanent floating sheets of ice that connect to a landmass.

Ice shelves form when ice from enormous ice sheets enters the sea through glaciers and ice streams. Low ocean temperatures prevent the newly arrived ice from melting and promote its growth.

Ice shelves can survive for thousands of years because they are protected by nearby landforms. It gains ice from the land and shrinks as it is calved off by icebergs.

The floating mass of ice does not directly contribute to sea-level rise. However, if an ice shelf collapses, the ice streams and glaciers that are constantly pushing on it would flow faster into the ocean. This then leads to a rise in sea level.

Collapse and Advance in Antarctica

The collapse of the Larsen A and B ice shelves on the eastern Antarctic Peninsula in 1995 and 2002, respectively, accelerated the flow of ice toward the ocean, contributing to sea-level rise.

New studies show that there is ice advance or ice growth in an area behind Larsen D.

An increasing trend in the number of icebergs calving from the eastern Antarctic Peninsula began in 2020. Scientists used a combination of historical satellite measurements and ocean records to map the advance.

Christie and his team surveyed the coastline of the eastern Antarctic Peninsula in 2003 and 2019 and found that 85% of the 1,400-km-long ice shelf underwent continuous advance.

Over the past two decades, the area went through an extensive retreat. However, the study suggests that changes in atmospheric circulation resulted in more sea ice being carried by the wind to the coast. As a result, the ice shelves in the area are advancing.

2019 Wendell Sea Expedition

During the expedition off the eastern Antarctic Peninsula, portions of the ice shelf were in their most advanced position since satellite records began in the early 1960s, according to Professor Julian Dowdeswell, the expedition's chief scientist and co-author of the study. Dowdeswell is also from SPRI.

The team used the expedition's findings, satellite imagery from the past 60 years, and state-of-the-art ocean and atmosphere models to conduct a detailed study of the spatial and temporal patterns of ice shelf change.

More Ice Shelf Calving and Icebergs

Studies are underway to predict how sea ice in Antarctica will evolve in response to climate change. Some models suggest that sea ice in the Southern Ocean may decrease overall, while other studies suggest the possibility of an increase in sea ice.

However, studies conducted by Christie and his team suggest that the breakup of icebergs in 2020 could signal the beginning of a change in atmospheric patterns and a return to a decline in sea ice.

Study co-author Dr. Wolfgang Rack of the University of Canterbury pointed out that the event could be a transition back to atmospheric patterns observed in the 1990s that encouraged sea ice loss. This could lead to further ice shelf calving soon.