Wind speed is indeed emerging as a key, yet often underappreciated, regulator of Earth’s carbon and water cycles, particularly on land.

Wind stilling (the observed multi-decadal decline in near-surface wind speeds, aka “terrestrial stilling”) is significantly improving water-use efficiency (WUE) in global grasslands by enhancing soil moisture retention.

“Terrestrial stilling” (declining near-surface winds) has been observed in many regions, linked to factors like land-use changes, vegetation growth increasing surface roughness, and atmospheric circulation shifts. This study highlights a positive side effect for these ecosystems, adding nuance to climate impacts on carbon and water cycles.

A paper published today (May 13, 2026) in Science Advances finds that declining wind speeds (“terrestrial stilling”) are helping global grasslands become more efficient at taking up carbon while using less water.

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Wind stilling shapes grassland water use efficiency by enhancing soil moisture retention

That’s the title of the new Science Advances paper (published May 13, 2026).

Precise Mechanism:

Wind stilling doesn’t just passively reduce evaporation — it creates a coupled biophysical feedback loop that enhances ecosystem water-use efficiency (WUE_eco = GPP / ET) in grasslands:

Direct aerodynamic effect: Lower wind speed reduces boundary layer conductance (g_bw) to water vapor. This slows the removal of moist air near the surface/canopy, directly suppressing soil evaporation (the dominant component of ET in many grasslands) and canopy transpiration.

Indirect humidity feedback: Reduced vapor exchange increases near-surface relative humidity and lowers vapor pressure deficit (VPD) locally, further decreasing evaporative demand.

Soil moisture bridge: The suppressed ET leads to higher soil moisture (SM) retention. This is critical in water-limited grasslands, where plants are highly sensitive to soil drying.

Stomatal response: With better SM availability, plants increase stomatal conductance (keep stomata more open longer). This boosts CO₂ uptake (higher GPP/carbon gain) while the overall water loss (ET) rises less than proportionally — hence higher WUE.

Quantitative insight from the study:

A 1% decline in wind speed → +0.31% GPP but –0.65% ET (driven mostly by soil evaporation reduction), with SM increasing ~0.38%. Structural equation modeling (SEM) confirmed the dominant pathways: wind → lower g_bw + higher humidity → lower ET → higher SM → higher stomatal opening → higher GPP.

This loop is stronger under drier conditions, providing a natural buffer against drought intensification.

Why Grasslands Are Special

Low-stature vegetation minimizes vegetation-wind feedbacks (unlike forests, where greening increases surface roughness and can complicate stilling signals).

Grasslands experience more pronounced stilling than other biomes.

They are predominantly water-limited, making SM retention particularly impactful for carbon-water coupling.

Evidence Strength (Multi-Line Convergence)

Observations: 991 meteo stations + 13 eddy-covariance flux towers.

Remote sensing + reanalysis: Consistent negative WUE-wind sensitivity.

Modeling: CMIP6 simulations + targeted wind-manipulation experiments in CLM5 (Community Land Model) to isolate causality.

Spatial scale: >80% of global grasslands show WUE gains from stilling.

Contribution:

Wind stilling explains 7.7–25.7% of observed/projected WUE increases — second only to CO₂ fertilization.

Temporal Dynamics (1983–2100)

Strong stilling 1983–2010 → WUE boost.

Partial recovery ~2011–2028.

Renewed (and potentially stronger) stilling post-2029, especially under high-emission scenarios.

Key caveat: CMIP6 models underestimate the magnitude of wind declines, implying real-world WUE gains and drought resilience may be larger than current projections.

This aligns with related work by the same team showing wind stilling boosts global vegetation GPP (with grasslands contributing disproportionately). It adds nuance to climate impacts: while warming/VPD increases can stress ecosystems, stilling provides a counteracting positive effect on carbon-water efficiency.

Limitations:

Benefits may saturate or interact negatively with extreme events (e.g., if precipitation changes dominate).

Attribution relies on statistical isolation and model experiments; real-world confounding (e.g., land use, aerosols affecting circulation) exists.

Future projections depend on uncertain wind trends (driven by land-use change, atmospheric circulation shifts, etc.).

This suggests grasslands have more built-in resilience to climate change than previously modeled, particularly for carbon sequestration and drought tolerance. It could inform conservation priorities, grazing management, and expectations for terrestrial carbon sinks. However, it doesn’t negate other threats like conversion to agriculture or extreme heat.

Published:  Science Advances

DOI: 10.1126/sciadv.aee4995

Authors: Haohao Wu, Congsheng Fu, Philippe Ciais, Zelalem A. Mekonnen, Lingling Zhang, Qing Zhu Jiafu Mao, Jianyao Chen, Dagang Wang and Guishan Yang 

Abstract

Covering more than 40% of Earth’s vegetated surface, grasslands critically regulate terrestrial carbon and water cycles. Their ecosystem water use efficiency (WUE_eco), the ratio of carbon uptake to water loss, governs drought resilience in these water-limited ecosystems. While global terrestrial wind speed declined substantially from the 1960s to 2000s followed by a recovery in the subsequent decade, the extent and mechanisms of its influence on grassland WUE_eco remain poorly understood. Using site observations, satellite data, Earth system models, and wind manipulation experiments, we found a consistent negative sensitivity of grassland WUE_eco to wind speed. Mechanistically, declining winds reduce evaporative water loss, improve soil moisture, and promote stomatal opening, thereby enhancing carbon uptake. Wind speed changes accounted for 7.7 to 25.7% of WUE_eco increases under historical and future climates, making wind the second most important climatic driver after atmospheric carbon dioxide. Since Earth system models underestimate observed wind speed declines, future WUE_eco increases and drought resilience may exceed current projections for global grassland.