In a landmark study published in Science on Oct 17, titled "Drought intensity and duration interact to magnify losses in primary productivity", Professor Yu Qiang from Beijing Forestry University (BFU), alongside 177 researchers from 126 institutions across 28 countries, reveals the intensifying and prolonged drought threats on global ecosystems.

The study demonstrates that as droughts become more intense and prolonged, grassland and shrubland ecosystems transition from gradual adaptation to abrupt and severe declines in productivity. Unlike previous region-specific studies, the study offers the first comprehensive global assessment of how drought intensity and duration interact to shape terrestrial ecosystems.

To overcome limitations in data comparability, the team applied standardized drought experiments at 74 grassland and shrubland sites across six continents. Over three to four years, they measured aboveground plant productivity using consistent methodologies, enabling direct cross-site comparisons and a robust evaluation of drought impacts.

"We observed that while ecosystems typically exhibit a degree of adaptive resilience during multi-year droughts, this capacity breaks down entirely under extreme conditions comparable to once-in-a-century events," explained Professor Yu. After four consecutive years of extreme drought, productivity losses increased by approximately 2.5-fold compared to the first year. These findings indicate that as droughts intensify and persist, ecosystems may undergo fundamental transformations—shifting from reduced functionality to rapid and potentially irreversible collapse.

The study delivers the first global-scale analysis of how drought intensity and duration interact, overcoming the long-standing limitation of examining these factors in isolation. It answers a central question in climate change research: how do stronger and longer-lasting droughts reshape ecosystems? The findings serve as a critical warning that extreme drought can push ecosystems beyond tipping points, sharply raising the risk of degradation and demanding proactive adaptation strategies.

This study improves predictions of how terrestrial ecosystems respond to future climate conditions. It also offers a scientific basis for adaptive management of grasslands and shrublands, more accurate carbon sink estimates, and the development of drought risk mitigation policies.

The paper lists Professor Yu Qiang alongside Professor Melinda Smith and Dr Timothy Ohlert of Colorado State University as co-corresponding authors. Professor Melinda Smith and Dr Timothy Ohlert also served as co-first authors.

Paper link: https://www.science.org/doi/10.1126/science.ads8144