The climate change-fueled demise of one of Antarctica’s largest icebergs, A-23A, has ironically fueled a surge in nature’s “biological carbon pump,” potentially capturing some of the fuel propelling the climate crisis.
Iceberg A-23A is nearing the end of its over four-decade life, adrift in warming seas, shedding ice, and covered in brilliant blue meltwater pools. Yet the chance of ice detaching from A-23A and its trailing meltwater is producing a massive phytoplankton bloom, removing carbon from the atmosphere and producing oxygen and food for marine herbivores.
Satellite Iceberg Views
On January 25, 2026, the Ocean Color Instrument aboard NASA’s PACE (Plankton, Aerosol, Cloud, Ocean Ecosystem) satellite picked up markers of phytoplankton abundance in the form of chlorophyll-a plumes emanating from around what remains of A-23A and its surrounding debris field.
“This bloom is too big and too clearly spreading from the icebergs not to be strongly linked to them,” said Grant Bigg, an emeritus oceanographer at the University of Sheffield.
Bigg has previously studied how icebergs can fertilize the Southern Ocean with phytoplankton, creating as much as a fifth of the region’s downward carbon flux. While he notes that the region has been documented to experience blooms unrelated to passing icebergs, various satellite imagery suggests a strong correlation in this instance.
An Iceberg Bloom
Photosynthetic life forms like phytoplankton rely on light and local nutrients to bloom, both of which can be increased by these icebergs, encouraging a bloom.
In the summer, turbulence and high winds can push phytoplankton too deep under the surface to receive proper sunlight, yet meltwater can act as a surface stabilizer, improving growth conditions. Additionally, that meltwater may be rich in iron, manganese, nitrates, and phosphates, important nutrients. Together, these elements can encourage phytoplankton growth.
Smaller icebergs appear to be producing more concentrated phytoplankton signals, which researchers attribute to a faster melt rate, dumping nutrients into the surrounding ocean at a greater pace.
However, it is possible that data processing issues may be skewing these results. Algorithms used to analyze the data may be overcorrecting for the agency of the ice’s bright surface, and undercounting the chlorophyll concentration around larger icebergs.
Life follows an iceberg
One researcher from NASA’s PACE team, Ivona Cetinić, found evidence in the project’s MOANA database of ocean color observations that organisms—specifically tiny picoeukaryotic phytoplankton—were thriving around these icebergs. These microscopic organisms are known for their rapid response to fluctuations in temperature and nutrient availability.
A larger variety of cyanobacteria called Synechococcus produced swirls to the west of the berg seen in PACE’s data. PACE is still refining its tools, working to identify larger varieties of phytoplankton that likely are present but have yet to be confirmed in the area.
Some research in this area is pushing iceberg responsibility for phytoplankton even further beyond the one-fifth figure presented by Bigg in earlier research, up to one-third. The primary question now is how long this iceberg-fed bloom will continue. Throughout February, A-23A continued to lose mass, yet it has managed to conserve enough to still meet the requirements for being a named iceberg and be traced by the U.S. National Ice Center.
As these icebergs sustain the phytoplankton that make up the bottom of the food chain, they soon become surrounded by life in search of a meal, such as fish and seabirds. Previous work has shown that these high-chlorophyll streaks can extend for hundreds of kilometers and last for months. Only time will tell how long this life-giving, carbon-sequestering meltwater can continue to flow until the iceberg disappears.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.