[1] 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.
[6][7][8] (ii) The variability of large-scale atmospheric circulation, associated with the poleward expansion of the Hadley cell[9] and the shifting of centers of action (i.e. anticyclones and cyclones) controlling changes in near-surface wind speed.
[14] (iv) The "global dimming", i.e., the decrease in the amounts of solar radiation reaching the Earth's surface due to increased aerosol and greenhouse gas concentrations, forces a stabilization of the atmosphere resulting in weak winds.
Most of the uncertainties behind the "global terrestrial stilling" debate resides in (i) the short wind speed data availability, with series starting in the 1960s, (ii) wind speed studies mainly carried on midlatitude regions where the majority of long-term measurements are available;[2] and (iii) the low quality of anemometer records as pointed out by the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC).
The European funded research project STILLING[22] is a current (2016–2018) initiative that aims to reduce this constraint by rescuing, homogenizing and recovering the longest and highest-quality wind speed series across the globe.
The "global terrestrial stilling" phenomenon is of great scientific, socioeconomic, and environmental interest because of the key impact of even small wind speed changes on atmospheric and ocean dynamics and related fields such as: (i) renewable wind energy;[23] (ii) agriculture and hydrology due to evapotranspiration;[24] (iii) migration of wind-dispersed plant species;[25] (iv) wind-related natural disasters;[21] (v) marine and coastal impacts due to wind-driven storm surges and waves;[26] (vi) dispersion of air pollutants;[27] among many other socioeconomic and environmental spheres.