Accelerating climate change is exacerbating severe droughts in the United States and worldwide, with exceptionally harsh ramifications for specific biomes, according to a new study by Swiss researchers.
Droughts like the famous 1930s Dust Bowl in the United States have had devastating environmental consequences over the last century. As researchers work to understand the long-term impacts of climate change, intensive data collection and analysis are revealing trends pointing to harsher and longer-lasting climate events in the future.
Climate Change is Increasing Drought Threats
The new study by the Swiss research team provides greater insight into multiyear droughts (MYDs) on a global scale. These prolonged climate events, which can last for years or even decades, are becoming increasingly frequent and pose serious threats to human agriculture and natural ecosystems. As soils dry out and water sources evaporate, crop failures, widespread tree mortality, and diminished ecosystem productivity exacerbate the challenges associated with reduced water availability.
While high-profile MYDs, such as Chile’s ongoing drought since 2010 and the 2000–2018 drought in the Western U.S., have drawn significant attention, smaller or more remote droughts often go underreported. To fully grasp global drought trends, climatologists must thoroughly investigate these less prominent events.
Investigating Climate-Driven Droughts
The Swiss team, led by Liangzhi Chen, analyzed an astounding 13,176 MYDs that occurred between 1980 and 2018. Their research relied on the standardized precipitation evapotranspiration index (SPEI), a dataset that compares precipitation levels with potential evaporative demand. Chen’s team then cross-referenced this data with remotely sensed greenness metrics to assess how MYDs impacted ecosystems. The findings were sobering.
Over the 38-year study period, MYDs were found to afflict nearly every continent. These droughts became more frequent and intensified in severity, with increasingly hotter and drier conditions. Each year, an additional 49,279 ±14,771 square kilometers were affected compared to the previous year. However, the impacts varied significantly across different biomes. Warm, wet ecosystems like tropical and subtropical forests demonstrated remarkable resilience to these difficult conditions, whereas grasslands, while initially vulnerable, often recovered quickly following drought events.
The Great Plains of North America fall under a biome designated “temperate grasslands” by the World Wide Fund for Nature, formerly The World Wildlife Fund. These areas are typically marked by a climate of cold winters, warm summers, and some rain.
The 500-950mm of rain these biomes receive annually usually places them between 300mm of deserts and 2,000mm of tropical forests. However, recent years have been anything but normal as MYDs become increasingly common.
Keeping A Close Eye On Future Events
Chen’s team suggests careful future monitoring to better understand the relationship between climate, drought, and the environment. The researchers acknowledge that plant mortality and physiological responses to drought require further investigation to develop a more comprehensive understanding of these interactions. This knowledge will also be critical for evaluating controversial climate intervention or manipulation proposals.
To this end, Chen advocates for enhanced remote sensing technologies to provide a clearer picture of drought impacts on the ground. For instance, while greenness metrics can indicate some effects of drought on vegetation, they may not fully capture the extent of damage. Satellite-based solar-induced chlorophyll fluorescence measurements could offer a more detailed assessment of plant stress and health. Similarly, tracking tree canopy temperatures may yield valuable insights into drought impacts.
The paper “Global Increase in the Occurrence and Impact of Multiyear Droughts” appeared on January 16, 2025 in Science.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.