Global ‘Stilling’: Is Climate Change Slowing Down the Wind?

Windy enough today?

This recent Yale Environment360 article came into focus today when Sky News headlined with: Future of renewable energy in balance as UK suffers wind drought – with ‘global stilling’ to come. Ironically, climate theory has it that warming will happen and will reduce wind speeds over the decades ahead. According to one expert (says Yale), a 10 percent decline in wind speeds would actually result in “a 30 percent drop [in output], and that would be catastrophic.”
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Last year, from summer into fall, much of Europe experienced what’s known as a “wind drought,” says Yale.

Wind speeds in many places slowed about 15 percent below the annual average, and in other places, the drop was even more pronounced.

It was one of the least windy periods in the United Kingdom in the past 60 years, and the effects on power generation were dramatic.

Wind farms produced 18 percent of the U.K.’s power in September of 2020, but in September of 2021, that percentage plummeted to only 2 percent. To make up the energy gap, the U.K. was forced to restart two mothballed coal plants.

The recent declines in surface winds over Europe renewed concerns about a “global terrestrial stilling” linked with climate change. From 1978 until 2010, research showed a worldwide stilling of winds, with speeds dropping 2.3 percent per decade.

In 2019, though, a group of researchers found that after 2010, global average wind speeds had actually increased — from 7 miles per hour to 7.4 miles per hour.

Despite those conflicting data, the Intergovernmental Panel on Climate Change forecasts slowing winds for the coming decades. By 2100, that body says, average annual wind speeds could drop by up to 10 percent.

“Why do we have wind at all on the planet?” asks Paul Williams, who studies wind as a professor of atmospheric science at the University of Reading in England. “It’s because of uneven temperatures — very cold at the poles and warm at the tropics. That temperature difference drives the winds, and that temperature difference is weakening. The Arctic is warming faster than the tropics.”

According to a recent study in Nature, the Arctic has, since 1979, been warming four times faster than the rest of the world. That’s much quicker than scientists had previously thought, and this warming could presage an even steeper decline in wind than anticipated.

Another factor possibly contributing to stilling is an increase in “surface roughness” — an uptick in the number and size of urban buildings, which act as a drag on winds.

Wind has been an overlooked element of climate change studies, which helps explain why the debate over these trends continues. The field is young, with only 70 years of data — temperature data, by contrast, goes back thousands of years — and wind systems are notoriously difficult to study and analyze. Substantial annual fluctuations make long-term trends difficult to detect, and conclusions are rarely firm.

Still, one recent pioneering study has shone light on the behavior of winds by examining where and how much dust settled on earth during the Pliocene era, when temperatures and carbon dioxide levels were similar to what they are today.

“By using the Pliocene as an analog for modern global warming, it seems likely that the movement of the westerlies” — the prevailing mid-latitude winds that blow from west to east — “towards the poles observed in the modern era will continue with further human-induced warming,” says Gisela Winckler, a researcher at Columbia University’s Lamont Doherty Earth Observatory and an author of the Pliocene dust paper.

Her models indicate “that the winds [will be] weaker, and stiller.”

Full article here.