- An expedition by more than 50 researchers from seven countries has documented the gradual degradation of Antarctica: microplastics in the water, melting ice, and declining salinity in the Southern Ocean.
- The team found microplastics in both glacial ice and seawater.
- They also noted that atmospheric “rivers” are sending ash-laden air from Amazon forest fires to Antarctica, hastening the melting of snow and ice there.
- The accelerated melting means more freshwater is rushing into the Southern Ocean, reducing the salinity level and affecting the phytoplankton that form the basis of the marine food chain.
Glaciers melting rapidly, fields of moss expanding, water streaming off ice shelves once frozen solid: these are just a few of the impacts of climate change observed by a team of 57 researchers during a 70-day voyage around the Antarctic coast on the Russian icebreaker Akademik Tryoshnikov. The expedition also revealed the presence of microplastics on the southern continent, and that the salinity of the Southern Ocean has decreased due to melting ice.
Antarctica is Earth’s fifth-largest continent and a key climate regulator. Together with the much smaller Arctic region, Antarctica redistributes the heat absorbed in the equatorial zone, balancing thermal energy. In other words, the ice masses in these two extreme locations of the planet are part of a huge circulatory machine that regulates energy, affecting the global climate. Led by Brazilian glaciologist Jefferson Cardia Simões, from the Federal University of Rio Grande do Sul’s Polar and Climate Center (CPC–UFRGS), the International Antarctic Coastal Circumnavigation Expedition (ICCE) took place in 2024. A total of 57 researchers from seven countries traveled 29,000 kilometers (about 18,000 miles), circling Antarctica and collecting snow, ice samples and seawater, to understand how the microbial life that inhabits this region is responding to climate change.
The team drilled into the ice, collecting samples that will shed light on the nature of the atmosphere at different times in history, as well as the presence of microplastics.
“Each layer of snow represents the precipitation at a specific moment, revealing the atmosphere at that time, the chemical components, and the amount of snowfall,” said Filipe Lindau, coordinator of the glaciology team at CPC-UFRGS.
The researchers also found the presence of plastic in liquid water.
“Microplastics were visible when seawater was passed through a kind of strainer; they could even be seen through the camera lens,” said Venisse Schossler, a climatologist and the mission coordinator.
During their circumnavigation, the researchers also measured the retreat of glaciers.
“We confirmed that the front of the Lange Glacier receded at least 400 meters [a quarter of a mile] between 1995 and 2025, after losing 1.38 kilometers [0.86 mi] between 1956 and 1995,” said climatologist Francisco Aquino.
Studies published by the U.S. National Snow and Ice Data Center indicate that since 2016, abnormal heat input into Antarctica has reduced the extent of sea ice by 6,500 square kilometers (about 2,500 square miles).
“This leads to a decrease in the production of krill, which resembles a mini shrimp and is the basis of the food chain in Antarctic fauna,” Schossler said.
The Antarctic and Amazon regions are linked by an atmospheric corridor, with cold air masses occasionally reaching the Brazilian state of Acre and the southern Amazon, causing temperatures to drop. At the same time, the “flying rivers” of water vapor rising up from the rainforest canopy can transport large volumes of moisture and even heat from the Amazon region as far south as Antarctica.
On the 20th day of the expedition, the team observed a cyclone approaching the Mill Island region of East Antarctica.
“We saw that there was a heat wave in Brazil associated with a mass of hot, humid air coming from the Amazon, crossing the Atlantic and reaching Antarctica,” Schossler said, adding that this air mass contributed to the formation of the cyclone and rain, accelerating the melting of Antarctica’s sea ice.
An increase in rainfall can have dire implications for animals not adapted to liquid precipitation.
“Penguins are born with feathers that protect them from snow, not rain,” said polar biologist Emanuele Kuhn. “Therefore, if the chicks get wet in water at temperatures of 1 to 2°C [33.8-35.6° Fahrenheit], they suffer stress and die of hypothermia. They are animals adapted to snow.”
Given the connection between Antarctica and the Amazon, when there is deforestation and fires in the latter, the resultant haze, loaded with fine particles, reaches the former.
“Air polluted by fires in the Amazon can carry black carbon — a highly heat-absorbing particle — to distant regions such as Antarctica,” Schossler said.
When these particles settle on snow and ice, they reduce their albedo — their ability to reflect sunlight — which accelerates melting. In addition, by remaining suspended in the atmosphere, black carbon contributes to global warming.
“We need to start understanding that, just like in the ocean, there are also waves in the atmosphere that, as they propagate, transfer heat and moisture that connect remote regions of the globe,” said Claudia Parise, a member of the expedition who studies ocean-atmosphere interactions.
Another impact observed by scientists is that the salinity level is declining due to the influx of meltwater from the glaciers. This directly affects phytoplankton, the microscopic algae that form the basis of the ocean’s food chain and play a key role in capturing carbon dioxide and producing oxygen.
“The reduction in salinity and increase in acidity in the oceans are deeply altering marine ecosystems, directly affecting phytoplankton, considered the lungs of the world,” Simões said. “Without it, there is a risk of imbalances throughout the marine food chain and impacts on the planet’s climate. These changes are occurring more rapidly in the polar oceans, which are particularly sensitive to climate change.”
Changes in salinity also affect ocean circulation, the complex system of water currents that move heat, nutrients and other elements throughout the oceans. These changes, in turn, alter the energy balance between the tropics and the poles.
Researchers warn that environmental concern focuses too much on the Amazon, ignoring the vital role that Antarctica also plays. They say the systems are interconnected: changes in Antarctica affect the tropics and vice versa.
“The polar oceans, especially because of their coldness, are the largest carbon sinks, and without them, we would have 40% more carbon dioxide in the atmosphere,” Simões said.
Everything is connected, Lindau agrees: “Antarctica, although remote, has a dynamic of constant connection and influences global climate regulation.”
Banner image: The icebreaker Akademik Tryoshnikov advances around Antarctica. Image courtesy of ICCE/Anderson Astor and Marcelo Curia.
This story was first published here in Spanish on April 28, 2025.
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