Daramola et al. (2026) Evaporative cooling exceeded albedo-induced warming in greening areas of global drylands

Identification

• Journal: Scientific Reports
• Year: 2026
• Date: 2026-02-14
• Authors: Mojolaoluwa Toluwalase Daramola, R. Li, Ming Xu
• DOI: 10.1038/s41598-026-36781-y

Research Groups

• Irish Climate Analysis and Research Units (ICARUS), Department of Geography, Maynooth University, Maynooth, Ireland
• Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
• University of Chinese Academy of Sciences, Beijing, China
• BNU-HKUST Laboratory for Green Innovation, Advanced Institute of Natural Sciences, Beijing Normal University at Zhuhai, Zhuhai, China
• Jiangmen Laboratory of Carbon Science and Technology, Hong Kong University of Science and Technology, Jiangmen, China

Short Summary

This study investigates the impact of greening and browning on temperature feedback in global drylands over the past two decades, revealing that evaporative cooling driven by soil moisture-controlled evapotranspiration largely outweighs albedo-induced warming.

Objective

• To quantify how recent greening and browning trends in global drylands modulate surface and air temperatures through moisture and radiation feedbacks, and to determine the dominant biophysical driver of these temperature changes.

Study Configuration

• Spatial Scale: Global drylands, defined by an aridity index (P/PET) less than 0.65.
• Temporal Scale: Two decades, specifically from 2001 to 2020.

Methodology and Data

• Models used: Global Land Evaporation Amsterdam Model (GLEAM v3.5) for evapotranspiration and soil moisture.
• Data sources:
  • Aridity Index: Consultative Group for International Agriculture Research (CGIAR) Consortium for Spatial Information.
  • Vegetation Dynamics (NDVI): Moderate Resolution Imaging Spectroradiometer (MODIS/Terra MOD13C2.006).
  • Surface Temperature (LST): Terra MODIS (MOD11C3) and Aqua MODIS (MYD11C3).
  • Air Temperature: Climate Research Unit (CRU TS 4.05) and ERA5 reanalysis (ECMWF).
  • Soil Moisture: GLEAM v3.5 and European Space Agency’s Climate Change Initiative (ESA CCI SM v06.1).
  • Evapotranspiration (ET), Vegetation Transpiration (VegT), Bare Soil Evaporation (BareE): GLEAM data products.
  • Surface Heat Fluxes (Latent Heat Flux, Sensible Heat Flux): ERA5 reanalysis.
  • Land Cover Type: MODIS/Terra+Aqua Land Cover Type (MCD12C1.006).
  • Land Surface Albedo (LSA): Computed from MODIS black-sky and white-sky albedo.
  • Vapor Pressure Deficit (VPD): Calculated using maximum, minimum, and dewpoint temperatures.
  • Statistical Analysis: Mann-Kendall trend test, Theil-Sen slope estimator, two-tailed Student’s t-test, partial correlation.

Main Results

• Global drylands experienced a significant greening trend (NDVI increase of 0.0073 per decade) between 2001 and 2020, with co-occurring browning in some regions.
• Evapotranspiration (ET) dominated the temperature feedback, accounting for approximately 54-83% of the total contribution to temperature change, with its effect on daytime surface temperature being up to 66% more dominant than surface albedo.
• Significant greening was associated with a decrease in daytime surface temperature of -0.53 °C and -0.8 °C per decade, while significant browning was associated with an increase of 0.86 °C and 1.32 °C per decade.
• Mean air temperature increased by 0.07 °C per decade in significantly greening areas and by 0.27 °C per decade in significantly browning areas.
• Soil moisture availability strongly controlled ET and its contribution to temperature feedback; greening did not necessarily lead to increased ET if soil moisture decreased.
• Shrublands exhibited the most intense warming due to browning and limited evapotranspiration, with a mean air temperature trend of 0.4 °C per decade.

Contributions

• Provides a comprehensive assessment of greening and browning effects on temperature feedback across global drylands, an area previously less studied compared to forested regions.
• Quantifies the relative contributions of moisture-driven cooling (evapotranspiration) and radiation-driven warming (surface albedo) to temperature changes in drylands, demonstrating the clear dominance of evaporative cooling.
• Emphasizes the critical role of soil moisture availability as the central regulator of vegetation-climate feedback in drylands, highlighting that greening alone does not guarantee warming mitigation without sufficient moisture.
• Extends regional findings on the dominance of evaporative cooling to a global dryland context, reinforcing its importance in moisture-limited but vegetated regions.

Funding

• National Key R&D Program of China (2018YFA0606500, 2023YFF0805900-03)
• National Natural Science Foundation of China (Nos. 41971060 and 42371055)
• Research Ireland (RI 22/CC/11103)
• University of Chinese Academy of Sciences (UCAS) Scholarship

Citation

@article{Daramola2026Evaporative,
  author = {Daramola, Mojolaoluwa Toluwalase and Li, R. and Xu, Ming},
  title = {Evaporative cooling exceeded albedo-induced warming in greening areas of global drylands},
  journal = {Scientific Reports},
  year = {2026},
  doi = {10.1038/s41598-026-36781-y},
  url = {https://doi.org/10.1038/s41598-026-36781-y}
}