New research is revealing how shifting wind speeds could affect everything from renewable energy to ocean evaporation
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By the 2010s, a worrying trend had caught the attention of climate researchers. Land-based weather stations across the mid-latitudes were recording a persistent, mysterious slowdown in near-surface wind speeds, a phenomenon dubbed ‘terrestrial stilling’. Research led by French climatologist Robert Vautard revealed that, between 1979 and 2008, surface wind speeds across North America, Europe and Asia had declined by roughly 5–15 per cent.
At the time, Vautard and his colleagues theorised that this stilling was caused, in part, by an increase in ‘surface roughness’ — in other words, increasing urbanisation and land-use changes were slowing down winds close to Earth’s surface. However, climatologists also suspected another culprit: global warming.
Then, in 2019, a landmark study upended that narrative, revealing that terrestrial stilling seemed to have undergone a sudden reversal. A group of researchers at Princeton University in the USA found that after 2010, average mid-latitude wind speeds had actually increased by around seven per cent. It was ‘good news for the power industry’, co-author Adrian Chappell, professor of climate change impacts at Cardiff University, said at the time.
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Wind energy generation often lies at the centre of conversations about wind stilling, but both a drop and a rise in wind speeds carry far wider repercussions, affecting everything from urban air quality and wildfire behaviour to soil erosion. Winds drive dust storms that can be hazardous to human health, but which also play a crucial role in fertilising the Amazon rainforest and the Atlantic Ocean. Surface winds also help sustain the Gulf Stream warming Western Europe.
In most cases, scientists remain uncertain about how shifting winds could influence these different processes. A recent study published in Geophysical Research Letters suggests that, despite rising sea-surface temperatures, global ocean evaporation has recently declined because wind stilling has reduced moisture transfer to the atmosphere. Another paper, published in Nature Communications, reveals that stilling may have reduced moisture loss in grasslands, boosting carbon uptake.
Concerns over terrestrial stilling resurfaced in the winter of 2021–22 during a European ‘wind drought’, when wind speeds dropped by roughly 15 per cent below annual averages. The UK saw its calmest period in 60 years, sending wind-power generation plummeting from 18 per cent in September 2020 to just two per cent 12 months later. The UK’s grid operator was required to call on two coal-fired power stations that were winding down commercial operations ahead of being decommissioned, to provide emergency backup, causing a surge in wholesale electricity prices.
Since then, a study published in Earth’s Future has warned that wind speed revivals observed since 2010 are unlikely to be a permanent trend, and that terrestrial stilling in the Northern Hemisphere looks likely to continue.
Rather than being driven solely by surface friction, long-term global warming is playing a role, the authors say. As the tropics and subtropics get hotter, rising air and storms in those regions are supercharged, sending huge plumes of warmth into the upper atmosphere. That air eventually cools and sinks back down over the mid-latitudes (the regions encompassing most of North America, Europe and Asia). This sinking air creates a stable, invisible lid over the lower atmosphere known as a subsidence inversion. Acting like a heavy blanket, it prevents vertical mixing and effectively stifles the horizontal gusts of wind that we feel at the surface.
In their 2019 paper, the Princeton University researchers also noted that while the recent upward trend in wind speeds would likely continue for roughly another decade, because this reversal was being driven by cyclical ocean-atmosphere oscillations (naturally occurring multi-decadal shifts that inevitably swing in the opposite direction), the temporary recovery would eventually reverse, giving way to resumed long-term declines.
The Intergovernmental Panel on Climate Change also projects that surface wind speeds will continue to decline across many mid-latitude and subtropical regions, driven largely by the accelerated warming of the Arctic and shifting atmospheric circulation patterns.
For now, however, the long-term trajectory for global surface winds remains uncertain, partly because research is heavily skewed towards the Northern Hemisphere, but also because wind research lags behind the decades of research into temperatures and precipitation. As Bill Gutowski, a professor of geological and atmospheric sciences at Iowa State University, noted while researching the phenomenon in 2009: ‘What we’re poking into here is not something that’s commonly explored.’
