A groundbreaking 40-year study has revealed a troubling surge in long-lasting, multi-year droughts (MYDs), which have become more frequent, drier, and expansive with the warming climate. The findings, published in Science on January 16, emphasize the global challenge posed by these persistent dry spells, warning of their devastating impact on ecosystems, agriculture, and water resources.
Between 1980 and 2018, global terrestrial land affected by MYDs expanded at an alarming rate of 50,000 square kilometers annually. Researchers documented 13,176 MYD events during this period, each lasting at least two consecutive years. These droughts not only grew in size but also experienced significant temperature anomalies in affected regions.
Notably, the study identified 10 of the most severe MYDs, which occurred across all continents except Australia, with some extending as recently as 2018. The most affected ecosystems were temperate grasslands, and regions such as central Chile, the western United States, and parts of central Africa faced the brunt of these events.
What Are MYDs?
MYDs are prolonged drought events that last years or even decades, leading to severe soil water depletion and reduced streamflow. These conditions can result in irreversible damage, including massive crop failures, increased tree mortality, diminished ecosystem productivity, and critical water shortages.
The study highlighted the vulnerability of ecosystems during such events, noting, “Prolonged water deficits can overshoot the tolerance of ecosystems, resulting in widespread loss of productivity, browning, and even vegetation dieback.”
Five of the top 10 most severe MYDs occurred between 2007 and 2018, including an eight-year drought in the eastern Congo basin that spanned over 1.49 million square kilometers. Similarly, the southwestern Amazon experienced a nine-year MYD, with its affected area peaking in 2015 at a size nearly equivalent to the United Kingdom.
El Niño events have played a significant role in exacerbating these droughts. The study found that years following major El Niño events, such as 1998, 2010, and 2015, saw the largest areas impacted by MYDs, demonstrating the far-reaching effects of these climate phenomena.
The researchers predict that MYDs will become even more frequent and severe in the 21st century. Rising global temperatures and increasing rainfall variability are expected to intensify these events, posing a serious threat to water security, food production, and biodiversity.
The authors urged global collaboration to mitigate and adapt to the challenges posed by MYDs, emphasizing the importance of effective preparedness and long-term resilience strategies. Their analysis serves as a critical benchmark for understanding and addressing the escalating risks associated with prolonged droughts in a warming world.
This study is a wake-up call to governments, policymakers, and communities to prioritize climate action and safeguard ecosystems against the mounting impacts of these relentless dry spells.