How disappearing Antarctic ice fuels a climate change reaction

With dire warnings about Antarctic Sea ice coming from a cadre of scientists earlier this month, OHIO Today sat down with the recipient of the 2024-2025 Graduate College Graduate Fellowship Nico Sartori to talk about the implications of Antarctic ice melt and how his research under Professor of Meteorology Ryan Fogt in the Scalia Laboratory is helping us understand how it affects the planet, and what it means for our future.

Besides being a tell that the planet is getting warmer, the loss of Antarctic Sea ice also exacerbates the problems associated with global warming. Sartori explains that sea ice reflects sunlight, keeping the ocean cooler. When there’s less ice, the dark ocean absorbs more sunlight, warming the water and air faster. “More open ocean allows more absorption of incoming solar radiation, which essentially accelerates global climate change and warming of the ocean and surface,” Sartori says. 

Scientists have known for decades that Arctic Sea ice is shrinking, with Nature reporting recently that the North Pole region’s first ice-free day could arrive in this decade. In contrast, Antarctic Sea ice grew until 2014 but has been shrinking since. Sartori points out that the Arctic is surrounded by land, so its ice stays in one area, while Antarctic ice is surrounded by open ocean and can spread out more. "The Arctic also contains freshwater sources from rivers that are less dense than the ocean, allowing for more ice formation, while the Antarctic contains saltier waters,” he says.

“Most of the Antarctic Sea ice does not survive its summer melt season whereas some ice in the Arctic does. In this case, the Arctic has multi-year, and much thicker, ice while the Antarctic does not.”

“Despite Antarctica being far from most civilizations around the world, it can cause major disruptions in the global climate,” Sartori says, explaining that as Antarctic Sea ice melts, ice on land also melts faster, adding more water to the oceans. This melting means there’s "less of a barrier to protect the grounded ice sheet where Antarctica sits on land, causing thinning of the ice sheets.... This melting will contribute to the impact [on] millions of lives who live along the coast due to sea level rise.”

Antarctic sea ice plays a big role in regulating global temperatures by reflecting sunlight back into space. Its loss amplifies warming through a feedback loop.

“Sea ice has a high albedo, meaning it can reflect more solar radiation from the sun,” Sartori says. “However, with less sea ice and less sea ice duration, that increases the open ocean, which has a very low albedo. More open ocean allows more absorption of incoming solar radiation, which essentially accelerates global climate change.”

This accelerating feedback loop highlights the urgent need to monitor and adapt to the changing conditions in the Antarctic.

The ocean heats up slowly, so changes take time, Sartori says. "Since the record lows are becoming consistent in recent years, it is possible we are reaching a tipping point, but it is hard to tell how close,” Sartori says, noting since it’s hard to know for sure because ice models aren’t perfect. “Further research is needed to determine how close we are to a tipping point.”

At Ohio University’s College of Arts and Sciences, Sartori is delving into the intricate patterns of Antarctic Sea ice, guided by Fogt’s extensive expertise. Using advanced statistical models and updated data, Sartori is exploring whether the ice is transitioning to an ocean-dominated system—a shift that could reshape global climate dynamics.

“Dr. Fogt created reconstructions of Antarctic Sea ice through 2020 using temperature, pressure, and climate data,” Sartori explains. “I’ve been updating these reconstructions through 2023, comparing them to recent record low observations to determine whether the ocean is playing a larger role.”

This work is powered by the Scalia Lab’s advanced computing resources, which enable Sartori to analyze vast datasets efficiently. The research not only enhances our understanding of Antarctic Sea ice variability but also equips scientists with better tools to predict future changes in the Earth’s climate system.

Antarctic Sea ice is important in driving global ocean circulation, particularly through the Antarctic Bottom Water, a dense and cold current that sinks and redistributes heat around the globe. However, as Sartori explains, melting sea ice releases freshwater into the ocean, making the water less dense and weakening this circulation.

“If the Antarctic Sea ice melts, more freshwater is input into the ocean, allowing the ocean to reduce in density since freshwater is less dense than saltwater,” he says. “This will decline the sinking process of the Antarctic Bottom Water and weaken at least in the high southern portion of the global ocean currents.”

The ripple effects of weaker currents could disrupt climate systems worldwide, leading to unpredictable changes in weather patterns, like what’s already being observed in the Northern Hemisphere.

Technological advancements, particularly satellite imagery and remote sensing, have provided decades of data on sea ice extent and variability. Sartori highlights how these tools have transformed our understanding of Antarctic Sea ice and climate interactions.

“Satellite imagery has helped substantially in tracking sea ice changes and variability since 1979 and has provided nearly 45 years of data,” he explains. “Advancements in modeling, as well as improving resolution and computational power, allow us to model more advanced dynamical processes that were difficult to analyze before.”

Beyond satellites, historical data is also helping fill out the picture. Sartori notes that Fogt’s efforts to digitize ship logbooks from the early 20th century are adding critical missing data to the picture, offering a longer historical record of sea ice and climate variability.

Sartori emphasizes the value of historical context when examining modern sea ice dynamics. By studying changes over the past century, researchers can better identify long-term patterns and refine predictive models.

“If we can understand sea ice patterns in the 20th century, then we will be able to become more knowledgeable on sea ice variability and interpret its current behavior with better context,” he says. “Understanding more about past variability can aid in predicting future sea ice as we continue to update model simulations.”

This work is particularly important as scientists investigate whether Antarctic Sea ice is undergoing a shift from an atmosphere-driven to an ocean-driven system.

By combining advanced technology, historical data, and ongoing research, Sartori’s work sheds light on the profound connections between Antarctic Sea ice and global climate systems. His research “Investigating A Potential New Sea Antarctic Sea Ice State in the Context of the 20th Century” not only deepens our understanding of these complex processes but also underscores the importance of preparing for the challenges ahead.