Global terrestrial stilling
Global terrestrial stilling is the decrease of wind speed observed near the Earth's surface (~10-meter height) over the last three decades (mainly since the 1980s), originally termed "stilling". This slowdown of near-surface terrestrial winds has mainly affected mid-latitude regions of both hemispheres, with a global average reduction of −0.140 m s−1 dec−1 (meters per second per decade) or between 5 and 15% over the past 50 years. With high-latitude (> 75° from the equator) showing increases in both hemispheres. In contrast to the observed weakening of winds over continental surfaces, winds have tended to strengthen over ocean regions. In the last few years, a break in this terrestrial decrease of wind speed has been detected suggesting a recovery at global scales since 2013.
The exact cause(s) of the global terrestrial stilling are uncertain and has been mainly attributed to two major drivers: (i) changes in large scale atmospheric circulation, and (ii) an increase of surface roughness due to e.g. forest growth, land use changes, and urbanization.
Given climate change, changes in wind speed are currently a potential concern for society, due to their impacts on a wide array of spheres, such as wind power generation, ecohydrological implications for agriculture and hydrology, wind-related hazards and catastrophes, or air quality and human health, among many others.