Southern Ocean storms help the planet absorb more heat

The Southern Ocean surrounds Antarctica and lies far from most human activity, but it plays a major role in Earth’s climate. It absorbs heat from the atmosphere and helps slow global warming. Without this effect, the planet would heat up much faster.

New research shows that storms over the Southern Ocean help the ocean absorb more heat. These storms mix the water in ways that many climate models do not fully include, which makes future climate predictions less reliable.

Scientists from the University of Gothenburg explored this problem and published their findings in Nature Geoscience.

Critical role of the Southern Ocean

The Southern Ocean connects three major oceans: the Atlantic, Pacific, and Indian. Water moves freely through this region and carries heat and carbon across the planet. This movement helps balance global temperatures.

The Southern Ocean absorbs more than 75 percent of the extra heat produced by human activity. That heat would otherwise stay in the atmosphere and raise air temperatures. Ice would melt faster and heatwaves would grow stronger.

Heat absorption depends on surface conditions. Wind strength matters. Calm water behaves very differently from stormy water. Until now, storm activity received far less attention than it deserved.

What storms actually do

Storms bring strong winds. These winds stir the ocean surface and break up layers of water that usually stay separate. Cold water rises from below and warm surface water moves downward.

This mixing cools the ocean surface, which allows the water to absorb more heat from the air. During stormy periods, the ocean takes in this extra warmth rather than leaving it in the atmosphere.

“Our research shows that summers with stronger storm activity generate lower surface temperatures across the Southern Ocean. Hence, a stormy ocean can absorb more heat from the atmosphere, than in calm weather,” said Marcel du Plessis, lead author of the study.

This process affects the wider climate system. Ocean heat uptake influences air temperatures, sea ice levels, and marine heatwaves. When the ocean absorbs less heat, the atmosphere keeps more of it.

Storms near Antarctica are changing

The research team studied storm patterns around Antarctica over several decades. Wind records and ocean data revealed clear trends.

Storms in this region have grown stronger over time. One main reason is the rising pressure difference between Antarctica and the Subtropics. A larger pressure gap drives faster winds that create stronger storms.

Stronger storms cause deeper mixing in the ocean, which improves heat absorption and makes storms a key part of how the Southern Ocean controls warming.

Where climate models fall short

Climate models guide decisions about climate policy and future planning. These models depend on accurate descriptions of how the ocean and atmosphere interact.

Many current models underestimate storm strength in the Southern Ocean. As a result, these models often show ocean surfaces that are too warm.

“That is why our findings are important, because a better representation of storm processes is essential for more accurate future climate projections,” said Marcel du Plessis.

When storm driven mixing is missing or weakened in models, heat uptake gets miscalculated. Over time, even small errors can grow into major uncertainty.

Studying one of the hardest oceans

The Southern Ocean presents serious challenges for research. Strong winds, large waves, and remote locations limit ship based studies. As a result, long term observations are difficult.

To deal with this, researchers used underwater and surface robots. These tools measured ocean temperature, salt levels, and weather conditions. Satellite data and climate models helped complete the picture.

This innovative approach made it possible to isolate storm effects and track how heat moves during active weather. Without these tools, such detail would be impossible to capture.

Southern Ocean storms and forecasts

The study links storm activity to changes in ocean warming over the past 20 years. That connection had not been clearly shown before.

“This is the first time we can clearly link Southern Ocean storms to changes in ocean warming and our climate variability over the past 20 years,” said Professor Sebastiaan Swart.

“Such results mean we can better understand how the ocean is warming today and thereby predict how our Earth’s climate may change in the future.”

Storms have the strongest impact during the Antarctic summer. That is when surface mixing boosts heat absorption the most. Winter brings different processes, including sea ice and deeper mixing, which remain harder to observe.

Understanding these missing pieces will take time. What is clear now is that storms over the Southern Ocean play a much larger role in Earth’s climate than once assumed.

The study is published in the journal Nature Geoscience.

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