We have a problem with “iceberg alley”. And it has nothing to do with ships.
New research has shown how water from icebergs changes marine ecosystems in its path.
Icebergs are masses of ice, some of them quite large, that roam the ocean and melt into its waters. This natural transit may be intensified by climate change. This is partly why these huge chunks of ice are a priority for many to study.
Melting. One of the latest studies on the subject has revealed important clues to the impact of melting icebergs on ocean ecosystems. The team responsible for the study oversaw on the spot marine environment around one of the largest icebergs ever seen, A-68A.
A-68A. The now missing giant ice floe had an area of about 5,800 km² in the Alicante province. It broke off from the Larsen C ice shelf in July 2017 under the name iceberg A-68. A-68A is the name given to the main iceberg after it began to break away.
The iceberg began a 2,500-kilometer (1,500-mile) journey that was supposed to take it north and end in April 2021. After nearly four years of travel, the iceberg broke up near San Pedro Island (also known as South Georgia). A-68A’s “epic journey” was also monitored from space by the US space agency NASA (and summarized in a short video).
Iceberg Alley. The route this ice block follows is known as iceberg alley“iceberg alley.” There are regions in the oceans of our planet with relatively intense iceberg movement. In the northern hemisphere, iceberg alley extends between the coast of Labrador and Newfoundland, on the east coast of Canada.
The Southern Hemisphere has its own alley, which starts from the Weddell Sea and extends towards San Pedro Island. There, these huge floating blocks of ice are moving, and it was here that a team of researchers on board the RRS James Cook analyzed the melting process of A-68A.
More than a drop of water in the sea. The huge volume of water ejected by an iceberg is a trifle in the global context of the world’s oceans. But at the local level, a recent study has shown that the effects of increased iceberg transit could be significant.
The team noticed that as this iceberg melted, the way the layers of ocean water were stratified changed. According to the team responsible for the study, this led to the movement of certain substances and phytoplankton to the depths. This, in turn, meant a redistribution of nutrients in the water.
The team also found phytoplankton in the waters around the iceberg that had emerged from the ice itself and been released during the melting.
RRS James Cook. The fieldwork took place in February 2021, during the final months of its life, around San Pedro Island. During the study, interest focused on the possibility of this giant iceberg running aground, thereby destroying part of the ecosystem located on the seabed around the island. Now, the team has published details of their work in a journal article. Progress in Oceanography.
Future problem. Icebergs are a natural phenomenon and there is nothing new about them. It is assumed that the marine ecosystems in the alleys where they are most common have become “accustomed” to their presence and impact. The problem is the foreseeable development of this dynamic.
Climate change threatens the polar ice sheets, meaning icebergs could appear along these avenues, further altering ecosystems in their path.
“Climate models predict that icebergs may break off Antarctic ice shelves more frequently in the future. So by understanding what happened with this event, we have a better idea of what effect they might have if or when they happen more often,” Sally Thorpe, a co-author of the study, said in a press release.
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Image | Lauren Dauphin, NASA