For years, scientists believed they had a decent handle on what was melting the ice in West Antarctica. Warmer oceans and stronger winds blowing in from the west – that was the popular theory.

But now, after running climate simulations using local data, researchers have discovered that we might have been looking the wrong way entirely. It’s not the westerly winds causing the biggest trouble – it’s the northerly winds.

Ice loss means rising seas

Antarctica holds most of the planet’s freshwater, frozen in a massive sheet of ice that covers an area bigger than the U.S. and Mexico combined.

That ice isn’t just sitting still. Some of it flows slowly into the ocean, held back by giant floating extensions called ice shelves. If the ice sheet in West Antarctica collapses, sea levels around the world could rise by as much as 20 feet.

Even small changes in how fast that ice melts can have huge consequences for coastal cities, global currents, and weather systems.

That’s why scientists have spent decades trying to understand what’s causing the West Antarctic ice sheet to shrink. It’s been getting smaller since at least the 1940s. But not all the pieces of the puzzle were adding up.

Tracking Antarctica’s hidden winds

The new study was led by researchers at the University of Washington (UW). They weren’t satisfied with the usual climate models, which often rely on global data and struggle with the lack of weather stations in Antarctica. So they decided to build something better.

They pulled in proxy data – long-term records preserved in things like ice cores, tree rings, and coral. These natural sources can give clues about past wind and weather patterns, helping fill in the gaps left by satellite data and on-the-ground observations.

“We thought that we were going to support what the climate models showed, which was that the westerly winds were getting stronger near the coast of Antarctica,” said Gemma O’Connor, lead author and a UW postdoctoral researcher.

“But there was no evidence of westerly winds strengthening in this part of Antarctica.” That finding was odd. If westerly winds weren’t to blame, what was?

Northerly winds drive the ice melt

The team used high-resolution simulations to test 30 different wind scenarios. Each run of the model applied a different wind pattern to see what happened to the ice over a five-year stretch. They repeated the process again and again.

One pattern kept showing up: when winds came from the north, ice loss accelerated. Westerly winds didn’t do much.

Northerly winds shifted sea ice, closing small open areas in the ice cover known as polynyas. These are basically patches where heat can escape from the ocean into the atmosphere. When the winds closed them off, the ocean held onto more of its heat.

“Sea ice is a really good insulator, it keeps the ocean relatively warm compared to the air,” said Kyle Armour, a UW professor. “When northerly winds close the polynyas, it reduces ocean heat loss, which means warmer waters and more melting of ice shelves below the surface.”

This hidden heating creates a chain reaction. As the warmer water melts the ice shelves from below, freshwater enters the salty sea. That mix causes a difference in density, which pulls even more warm ocean water into the region – speeding up the melt further.

A climate connection we didn’t expect

The big question is: what’s making those northerly winds stronger? Early signs point to climate change.

Emissions of greenhouse gases are likely decreasing air pressure over the Amundsen Sea, a region that shapes many of Antarctica’s weather patterns. Lower pressure strengthens the northerly winds – the same ones that are making the melt worse.

“This mechanism provides a connection between West Antarctic ice loss and human-induced climate change, albeit a different mechanism than we previously suspected,” O’Connor said.

This isn’t just a scientific curiosity. It’s a real link between our actions and the future of the world’s ice. If our emissions are playing a role in these winds, then reducing those emissions could slow the melting.

“We know the Earth is warming up on average, but that alone doesn’t explain ice loss in Antarctica,” said Eric Steig, professor of Earth and space sciences at UW.

Northerly winds change the story

For decades, the focus has been on westerly winds – the ones that blow from west to east across the Southern Hemisphere.

Scientists thought they were pushing warm ocean water toward Antarctica and driving the ice to melt faster. But they missed something important.

“I think what Gemma has done is going to lead to a complete revolution in the understanding of what drives Antarctic ice loss,” Armour said. “We had all sorts of theories about the winds that blow from west to east, but the northerly winds weren’t even on our radar. We were off by 90 degrees.”

The lesson here is clear. Climate science is constantly evolving, and even long-standing ideas can be turned on their head. In this case, or rather, on their side.

Understanding which way the wind is blowing – literally – might be one of the keys to protecting the future of Earth’s ice.

The full study was published in the journal Nature Geoscience.

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