Swirling underwater “storms” are quickly melting the ice shelves of two important Antarctic glaciers. This has major implications for global sea level rise.
Antarctica looks like a fist with a thin thumb extending toward South America. The Pine Island Glacier sits near the thumb’s base, and the Thwaites Glacier, often called the Doomsday Glacier, is right next to it. Both glaciers have melted rapidly in recent decades due to warming ocean waters, particularly at the point where they rise from the seabed and become ice shelves.
A recent study in Nature Geosciences is the first to document how the ocean can melt ice shelves over very short time frames—hours and days. Yoshihiro Nakayama, a study author and engineering professor at Dartmouth College, emphasized the unique timing aspect. “We’re observing the ocean in ways not typically done in Antarctic research,” he noted.
The researchers focused on fast-changing, swirling ocean eddies known as submesoscales. Think of these as fast-twirling water twirls, similar to stirring cream into coffee. However, these ocean eddies can span up to about six miles and form where warm and cold water converge. Their rapid movement underneath ice shelves stirs up warmer water from deeper layers of the ocean, increasing melting where it hits vulnerable ice.
To study the impact of these underwater storms, scientists combined computer models with real-world ocean data. They found that these storms contributed to about 20% of the melting in the two glaciers over a nine-month timeframe. While estimating the exact role of the storms is tricky due to their chaotic nature, it’s clear they play a significant role in ice melting.
What’s more concerning is a feedback loop caused by these storms. As the ice melts, fresh cold water enters the ocean and mixes with warmer, saltier water below. This leads to more turbulence, further accelerating ice melting. “This feedback loop could intensify as the climate warms,” stated Lia Siegelman from UC San Diego’s Scripps Institution of Oceanography.
The implications are serious. Ice shelves hold back glaciers, and the Thwaites Glacier alone contains enough water to raise sea levels by over two feet. Its collapse could trigger a total sea level rise of around ten feet, which would have catastrophic effects.
Experts have weighed in on the importance of the study. Tiago Dotto, a senior research scientist at the National Oceanography Centre in the UK, remarked on how it underscores the role of smaller ocean features in melting ice shelves. “The extent of the ice melt found in this study is astonishing,” he said.
However, significant uncertainties remain. Antarctic ice shelves are among the least accessible locations on Earth. As David Holland, a professor at NYU, pointed out, relying on simulations alone may not paint the complete picture. “Much more real-world data is needed to thoroughly understand these eddies and their role in ice melt,” he stressed.
Additionally, many factors contribute to ice melt on the continent. “Hundreds of elements influence ice sheet decay,” noted Ted Scambos from the University of Colorado Boulder. He added, “We’re rapidly evolving our understanding of near-ice-sheet ocean dynamics.”
The research indicates that more data is essential to comprehend how underwater storms might fluctuate over longer periods. Nonetheless, these short-term processes are critical to understanding ice loss and sea level rise, as Siegelman emphasized. “Studying these ocean phenomena is key to grasping the complexity of ocean-ice interactions,” she concluded.
As these studies evolve, they become pivotal in revealing the intricate relationships between ocean currents and ice melt, shaping our understanding of future sea level rise.
