Testing “Global Stilling” with ERA-5 Reanalysis Data

"Global Terrestrial Stilling," a noticeable decrease in wind speeds around the globe, has been reported, with implications for energy generation and other environmental phenomena. The two leading possible causes are increased surface roughness due to land use changes and general climate changes. However, some long-term regional studies show no trend toward decreasing wind speeds. Global wind speed data since 1979 is available in reanalysis datasets. Here, we use ERA5 to map decadal averages of 10m wind speed. From the decadal mean ten meter wind speed map, we got that in the 1980s, the average wind speed was 6.29 m/s, and in the 2010s, it was 6.19 m/s. The results show a complicated pattern of small increases (within 5% of zero) and significant increases (10 to 20%) spread out in the equatorial regions. There are also decreases (5 to 10%) in the Polar Regions and parts of southern Asia, Europe, and other places. However, from the 1980s to the 2010s, there was a significant decrease in global wind speed of -2.67%. This trend suggests that wind speeds have decreased over time, with a particularly sharp decline in the past two decades.