A reversal in global terrestrial stilling and its implications for wind energy production

Abstract

Wind power is a rapidly growing alternative energy source to achieve the goal of the Paris Agreement under the United Nations Framework Convention on Climate Change, to keep warming well below 2 •C by the end of the 21 st century. Widely reported reductions in global average surface wind speed since the 1980s, known as terrestrial stilling, however, have gone unexplained and have been considered a threat to global wind power production. Our new analysis of wind data from in-situ stations worldwide now shows that terrestrial stilling reversed around 2010 and global wind speeds over land have recovered most of the losses since the 1980s. Concomitant increased surface roughness from forest growth and urbanization cannot explain prior stilling. Instead we show decadal-scale variations of nearsurface wind are very / quite likely caused by the natural, internal decadal ocean/atmosphere oscillations of the Earth's climate system. The wind strengthening has increased the amount of wind energy entering turbines by 17 ±2% for 2010-2017, likely increasing U.S. wind power capacity by 2.5%. The increase in global terrestrial wind bodes well for the immediate future of wind energy production in these regions as an alternative to fossil fuel consumption. Projecting future wind speeds using ocean/atmosphere oscillations show wind turbines could be optimized for expected wind speeds, including small and large speeds, during the productive life spans of the turbines. Reports of a 8% global decline in land surface wind speed (~1980 to 2010) have raised concerns about output from future wind power 1-5. Wind power varies with the cube of wind speed (u) 6. The decline in wind speed is evident in the northern mid-latitude countries where the majority of wind turbines are installed including China, the U.S. and Europe 1. If the observed 1980-2010 decline in wind speed continued until the end of the century, global u would reduce by 21%, halving the amount of power available in the wind. Understanding the drivers of this long-term decline in wind speed is critical not merely to maximize wind energy production 9-11 but also to address other globally significant environmental problems related to stilling, including reduced aerosol dispersal, reduced evapotranspiration rates, and adverse effects on animal behavior and ecosystem functioning 1,3,4,12. The potential causes for the global terrestrial stilling are complex and remain contested (e.g.,

An analysis of the urbanization contribution to observed terrestrial stilling in the Beijing–Tianjin–Hebei region of China

“…At the global scale, besides northern China, rapid declines in NSWS were also observed in eastern North America, northeastern Europe, Siberia and even over the Tibetan Plateau (You et al 2014, Zeng et al 2018, Zhang et al 2019b, where urbanization is very slow or negligible. A recent study indicated that decadal-scale variations of NSWS was dictated by internal decadal climate variabilities, rather than by the local impact of urbanization (Zeng et al 2019). This is consistent with our key finding that urbanization played a minor role in terrestrial stilling, even in this rapidly developing region.…”

“…Meanwhile, Fu et al (2011), Lin et al (2013) and Chen et al (2013) suggested that natural climate variability, such as the Pacific Decadal Oscillation and Arctic Oscillation, may be the primary driver for NSWS change in China. Recently, Zeng et al (2019) found a reversal in global terrestrial wind speed and attributed it to internal decadal atmosphere-ocean oscillations. Compared with the strong decline in NSWS observed at in situ weather stations, NSWS trends derived from reanalysis products and radiosonde records are much weaker (Vautard et al 2010, Chen et al 2013, Lin et al 2013.…”

Variability of Daily Maximum Wind Speed across China, 1975–2016: An Examination of Likely Causes

“…Contrary to this stilling phenomenon, positive near-surface daily mean wind speed trends have been reported over oceans (Wentz et al 2007), for coastal areas (Pinard 2007), and in high-latitude regions (i.e., .708;McVicar et al 2012;Minola et al 2016). Moreover, after 3-5 decades of stilling, a stabilization or ''recovery'' of global average terrestrial winds commenced in 2013 (Tobin et al 2014) and has continued in the last years (Dunn et al 2016;Azorin-Molina et al 2017Zeng et al 2019). Regional studies have also documented this recent recovery of land surface wind speeds (Kim and Paik 2015;Azorin-Molina et al 2018b;Zhang et al 2019).…”

Discussion on A high‐resolution bilevel skew‐tstochastic generator for assessing Saudi Arabia's wind energy resources

“…Another point worth mentioning is that the WRF output used is from a 6-year period in the past. Recent studies show that climate change is causing wind speed patterns to change over relatively short time horizons (on the order of a few decades) that span the planning, construction, and production phases of wind energy plants (Zeng et al, 2019). Could this be an issue, and is it possible to somehow adapt the framework to reliably generate wind demand patterns over the next few decades?…”