28 JAN 2026 (WED) 10:00-11:00

GEOG HKU
4 days ago
2 min read

Departmental Research Seminars Series

Assessing irrigation-induced impacts from a multi-model perspective

Date: 28 JAN 2026 (Wednesday)

Time: 10:00-11:00 (HKT)

Venue: CLL, Department of Geography, 10/F, The Jockey Club Tower, Centennial Campus, HKU

Registration link: https://hkuems1.hku.hk/hkuems/ec_hdetail.aspx?guest=Y&ueid=104653

Abstract:

Irrigation rapidly expanded during the 20th century, affecting climate via water, energy, and biogeochemical changes. Previous assessments of these effects predominantly relied on a single Earth System Model, and therefore suffered from structural model uncertainties. Here we quantify the impacts of historical irrigation expansion on climate and land water resources by analysing simulation results from six Earth system models participating in the Irrigation Model Intercomparison Project (IRRMIP). Results show that irrigation expansion causes a rapid increase in irrigation water withdrawal, which leads to less frequent 2-meter air temperature heat extremes across heavily irrigated areas (≥4 times less likely). However, due to the irrigation-induced increase in air humidity, the cooling effect of irrigation expansion on moist-heat stress is less pronounced or even reversed, depending on the heat stress metric. We also show that irrigation expansion in many regions substantially decreases the net water influx from the atmosphere to land, further aggravating the existing drying trends caused by climate change. For example, irrigation expansion changed the trend of this net influx from −0.664 ( ± 0.283) to −1.461 ( ± 0.261) mm yr−2 in South Asia after 1960. Consequently, the local terrestrial water storage depletion rate is substantially enlarged by irrigation expansion (for example, from −2.559 ( ± 0.094) to −16.008 ( ± 0.557) mm yr−1). In summary, this study indicates that irrigation deployment is not an efficient adaptation measure to escalating human heat stress under climate change, and it escalates the water loss from land, calling for carefully dealing with the increased exposure of local people to moist-heat stress and water depletion.

Dr. Yao YI

Post-doctoral Scientist, ETH Zurich, Switzerland

Dr. Yao Yi is a climate scientist specialising in land-climate dynamics, hydrology, and Earth system modelling. He obtained his PhD in Climate Science from the Vrije Universiteit Brussel (Free University of Brussels), Master’s in GIS from Beijing Normal University, and Bachelor’s in Hydraulic Engineering from Wuhan University. He is currently a post-doctoral researcher in the Institute for Atmospheric and Climate Science, ETH Zurich. His research focuses on the impacts of human activities on energy, hydrology, and climate, with his rich expertise in Earth System and Regional Climate Modelling, including CESM2 and COSMO-CLM. He is active in community work, e.g., he launched and coordinated the IRRigation Model Intercomparison Project (IRRMIP), and actively participated in the discussion on the Community Earth System Model forum. His research outputs are published on high-impact journals like Nature Water, Nature Communications, Journal of Advances in Modeling Earth Systems, etc.