Melting sea ice in Antarctica causes ocean storms, scientists say

PARIS — The record-breaking retreat of Antarctic sea ice in 2023 has led to more frequent storms over newly exposed parts of the Southern Ocean, according to a study published on Wednesday.

Scientists know that the loss of Antarctic sea ice can diminish penguin numbers, cause ice shelves to melt in warmer waters, and impede the Southern Ocean from absorbing carbon dioxide.

But this new research, published in the peer-reviewed journal Nature, explores another consequence: increased heat loss from the ocean to the atmosphere, and an associated rise in storms.

Since 2016 there has been a large-scale reduction in Antarctic sea ice, but nothing like 2023 when a record amount failed to reform over the winter.

For this study, Simon Josey of the UK's National Oceanography Centre and colleagues focussed on three regions that experienced unusually high levels of sea-ice retreat that year.

Using satellite imagery, ocean and atmospheric data, and wind and temperature measurements, they found some newly ice-free areas experienced double the heat loss compared to more stable period before 2015.

This was accompanied by "increases in atmospheric-storm frequency" over previously ice-covered regions, the authors found.

"In the sea-ice-decline regions, the June-July storm frequency has increased by up to 7 days per month in 2023 relative to 1990-2015."

The loss of heat caused by reduced sea ice could have implications for how the ocean circulates and the wider climate system, the study added.

Oceans are a crucial climate regulator and carbon sink, storing more than 90 percent of the excess heat trapped near Earth's surface by greenhouse gas emissions.

In particular, sea-ice retreat could mean changes in how a deeper layer of cold, dense Antarctic bottom water absorbs and stores heat.

The authors said further in-depth analysis of possible climate impacts were needed, including if sea-ice retreat could have even further-reaching consequences.

"Repeated low ice-cover conditions in subsequent winters will strengthen these impacts and are also likely to lead to profound changes further afield, including the tropics and the Northern Hemisphere," it said.