A vast, snow-covered Antarctic landscape with rugged white mountains under a clear blue sky. In the foreground, deep blue ocean waters contrast sharply with the brilliant white ice and snow of the coastline and glacier-covered peaks.

From the tropics to the pole: How El Niño touches Antarctica

A team of Australian climate scientists has explored how weather patterns in the tropical Pacific Ocean can influence the chemistry of snow falling thousands of kilometres away in Antarctica.

Working with an ice core drilled at Mount Brown South in East Antarctica, the researchers studied traces of sea salt preserved in layers of snow and ice. These salts, carried inland from the Southern Ocean by Antarctic storms, act like tiny chemical fingerprints of past weather. By analysing how the amount of salt changes from year to year, the team uncovered a surprising connection between the tropics and the frozen continent.

They found that during El Niño events – when the central Pacific Ocean warms – winds near 60 degrees south become stronger. These strengthened westerly winds whip up more sea spray and stir the edges of the sea ice, creating extra salt particles that can travel inland and fall with the snow at Mount Brown South. The result is higher salt concentrations in the ice core during El Niño years.

“What happens in the tropics doesn’t stay in the tropics,” said lead author Helen Shea, a PhD student from Monash University. 

“Our study shows that when the Pacific warms during El Niño, it strengthens the winds around Mount Brown South, Antarctica, enabling new sea ice to form and stirring up more sea salt that ends up locked in the ice. It’s a striking example of how connected Earth’s climate really is.”

The reverse pattern, La Niña, does not have the same effect, suggesting that the link between the tropics and Antarctica is not symmetrical. Interestingly, the number and strength of Antarctic storms did not change much between high-salt and low-salt years. What changed was how much salt was available for the storms to carry – depending on the winds and how much sea ice formed to the north of the site.

This discovery matters because the amount of sea salt in Antarctic ice can reveal how sea ice and wind patterns close by have varied through history, long before satellites began observing them. The Mount Brown South ice core, which extends back more than a thousand years, gives scientists a new window into how the nearby Southern Ocean and East Antarctica have responded to natural climate shifts.

The study highlights how connected our planet’s climate systems are – warming waters in the Pacific can send a chain reaction of winds and sea ice advance that eventually stir up more salt in a specific part of Antarctica. Understanding these links helps researchers interpret past climate change and improve predictions of how Antarctica and the global climate might behave in the future.

The results have been published in the European Geosciences Union journal Climate of the Past, and are available here.

This article was written using a combination of human and artificial intelligence.