The westerly winds are changing, and the consequences are unknown

The westerly winds have an effect on the weather and climate both locally and globally. These winds influence precipitation patterns, ocean circulation, and tropical cyclones. For this reason, it is critical for scientists to gain a better understanding of how the westerly winds may be altered by climate change.

The westerlies typically blow from west to east across the middle latitudes, but experts have noticed in recent decades that these winds have begun migrating toward the poles. While research suggests that this shift is caused by climate change, scientists have debated whether the winds will continue to migrate as atmospheric CO2 and temperatures rise. 

Prior to this study, little was known about the behavior of the westerly winds during past warm climates. Experts at Columbia University’s Earth Institute have developed a method to track the history of the winds, which will provide clues as to what will happen in today’s warming world. The researchers found evidence to suggest that atmospheric circulation patterns will change with climate warming.

The experts used dust in deep sea sediments to reconstruct wind patterns that occurred three to five million years ago. The sediment cores examined for the study were from the North Pacific Ocean, which is downwind from Eastern Asia, one of the largest dust sources for the past several million years. 

By measuring the dust in cores from two different sites that were thousands of kilometers apart, the researchers were able to map changes in dust and in the westerly winds.

“We could immediately see the patterns. The data are so clear. Our work is consistent with modern observations, and suggests that wind patterns will change with climate warming,” said study lead author Jordan Abell.

During the warm spells of the Pliocene three to five million years ago, the Earth was about two to four degrees Celsius warmer than it is today, yet had approximately the same concentration of CO2 in the atmosphere. The study revealed that, at this time in history, the westerly winds were located closer towards the poles than during the colder intervals afterwards.

“By using the Pliocene as an analogue for modern global warming, it seems likely that the movement of the westerlies towards the poles observed in the modern era will continue with further human-induced warming,” explained study co-author Gisela Winckler.

Storm systems and precipitation patterns will be enormously impacted by the movement of these winds. Although the research does not indicate exactly which regions of the world will be affected most in the coming decades, it confirms that the wind and precipitation patterns will change with climate warming.

“In the Earth history record, tracking down movements of wind and how they’ve changed, that’s been elusive because we didn’t have a tracer for it,” said Winckler. “Now we do.”

The study is published in the journal Nature.

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By Chrissy Sexton, Earth.com Staff Writer