The reduction of sea ice and the escalating ocean temperatures encircling Antarctica significantly influence the Earth’s climate, yet the capacity to monitor these changes is falling behind.
A persistent lack of observations in the expansive ocean encircling Antarctica is impeding the ability to make more precise predictions about the repercussions of the climate crisis, as confirmed by a gathering of 300 scientists. The Southern Ocean wields a disproportionate impact on the Earth’s climate, absorbing a significant amount of the additional heat and carbon dioxide resulting from human activities.
However, as the region undergoes profound transformations, marked by unprecedentedly low levels of sea ice, the ocean is likened to a “data desert,” according to the researchers. The week-long conference in Hobart, which concluded on Friday, brought together around 300 scientists from 25 nations. Organized by the Southern Ocean Observing System (Soos), a significant global scientific endeavor focused on enhancing and coordinating observations around Antarctica.
The closing statement of the conference highlighted that the Southern Ocean is experiencing “significant transformations,” evident in unprecedentedly low sea-ice levels, remarkably high temperatures, and noteworthy fluctuations in penguin populations.
“The ongoing scarcity of observations in the Southern Ocean poses a challenge to our capacity to identify and evaluate the outcomes of these changes,” the statement emphasized.
During the last two southern hemisphere summers, the sea ice encircling Antarctica has reached its lowest recorded extents. As the region approached the height of winter this week, satellite data revealed a deficit of approximately 2.5 million square kilometers compared to the long-term average. Scientists have characterized this exceptional ice loss during winter as unprecedented.
“We were entirely caught off guard by this; it came as a complete surprise due to shortcomings in our observation system,” remarked Dr. Andrew Meijers, an oceanographer affiliated with the British Antarctic Survey.
According to him, worldwide climate models encountered difficulties in replicating shifts in the Southern Ocean primarily due to data deficiencies. While satellites effectively tracked the extent of ice coverage over the ocean, there remained a significant dearth of information regarding ice thickness and alterations occurring beneath the ice.
“Ocean warming is essentially synonymous with global warming, and the Southern Ocean dictates the pace at which the Antarctic ice sheet melts – a pivotal factor in the most uncertain aspect of predicting future sea level increases,” he explained.
Antarctica’s ecosystems were intricately connected to the proliferation of phytoplankton and krill, which, in turn, relied on the yearly patterns of sea ice, Meijers explained.
Earlier this month, researchers studying Antarctica cautioned that the frequency of extreme events across the continent and its surroundings, ranging from sea ice depletion to ice sheet melting and heatwaves, would inevitably escalate as global warming persisted.
In the current year, researchers discovered that a profound oceanic current within Antarctica, responsible for transporting nutrients globally and exerting an impact on the climate, has decelerated by approximately 30% since the 1990s. A distinct study indicated that this decrease, attributed to heightened ice melting in Antarctica, is anticipated to amplify in the forthcoming decades.
Dr. Sian Henley, co-chair of Soos and a marine scientist affiliated with the University of Edinburgh, emphasized that the Southern Ocean played a “disproportionately” significant role in the global climate system.
Approximately 90% of the surplus heat retained by the Earth due to human activities such as fossil fuel consumption and deforestation has been absorbed by the world’s oceans. Within this, around 75% of the heat absorption occurred within the Southern Ocean, as highlighted by Henley.
Oceans additionally assimilate roughly 30% of the excess CO2 resulting from human actions, with approximately 40% of this absorption occurring within the Southern Ocean. Henley remarked:
“When you consider global ocean coverage, observations have expanded. However, the Southern Ocean remains relatively uncharted in terms of data. There persists a consistent scarcity of data to confront some of the most urgent inquiries.”
“There’s a stark clarity now that Antarctic sea ice is in a precarious state, which consequently places its role within the climate system at risk,” commented Dr. Ken Johnson, an ocean chemist at the Monterey Bay Aquarium Research Institute.
Also present at the conference was Dr. Johnson, who spearheads a project involving the deployment of numerous ocean floats equipped with sensors to measure temperature, salinity, oxygen concentrations, pH, and nitrate levels.
“The Southern Ocean functions as Earth’s climate engine. However, just when the need for increased measurements is crucial, our monitoring efforts are diminishing,” remarked Johnson.
He noted that the quantity of observations derived from sensors aboard cargo ships had been dwindling, leaving vast stretches of ocean, particularly during the southern hemisphere winter, unmonitored for thousands of kilometers.