A new study has examined the future intensity and timing of droughts across vulnerable areas of the world. Researchers found unprecedented drought would become more frequent and consecutive in certain “hotspot” regions, even under low future warming projections.

The study, led by the National Institute for Environmental Studies (NIES) Japan and published in Nature Communications, modelled changes in the frequency of drought days (FDD) for 59 global subcontinental regions until the end of the 21st century. This enabled them to identify periods in which droughts will shift to an “unprecedented” state. The researchers modelled two projected greenhouse gas emissions scenarios: one consistent with the Paris Agreement (RCP2.6) and a high emission scenario (RCP8.5).

The results showed that 25 per cent of the world’s land can expect an increase in drought by the mid-century in the low-emissions scenario. Under the high emissions scenario, the affected areas rise to 28 per cent. The projected warming impacts show significant regional disparities in their intensity and pace of growth over time. The most impacted areas show substantial increases of more than double compared to 1971-2005.

“Some regions exhibit steady increases in drought frequency. The projected increases are highly likely by the middle of this century compared to the historical period”, said the corresponding lead author Yusuke Satoh, a research associate professor at Korea Advanced Institute of Science & Technology. Therefore, drought conditions becoming more frequent will create a new normal, according to him.

Implications for water, food and energy

This is the first study to report the time of the first emergence of unprecedented regional drought conditions with regard to river discharge on a global scale. It is essential to consider river discharge, explained the scientists, because they are integral to understanding the future impacts of drought on water, food and energy security during climate change.

Given current natural resource management practices and existing infrastructures in these sectors are based on historical climatic conditions, it is critical to understand how the future impacts of global warming evolve over time. This allows regions to adopt sufficient climate change response strategies, including adaptation measures for the onset of these droughts.

The drought impact in Australia

The most affected regions identified in the study include Australia, Mediterranean regions and southern and central South America. For Australia, under both scenarios, much of the country would experience between 100 per cent and 200 per cent relative increase in the frequency of drought days (FDD) under climate change (see image above). 

The impact of drought on water and food security and energy systems has wide-ranging and severe socio-economic effects. Farmers and rural communities, in particular, are often on the frontline of the impacts of drought. For example, a 2021 study found that Australia’s lower rainfall and higher temperatures have already impacted farms’ productivity and profits. Another recent study found a correlation between climate-induced drought and increased suicides in rural Australia. 

Countries must prepare for the inevitable

Because more frequent and consecutive droughts are predicted even under the low-emission scenario, the results suggest that these future drought events are already inevitable in certain regions. Therefore, even in the best-case scenario, “the results imply unavoidable unprecedented states in these regions”, said Hideo Shiogama, a co-author and head of the Earth System Risk Analysis Section at NIES.

However, reducing greenhouse gas emissions as rapidly and deeply as possible remains essential. This is because the differences between the two scenarios indicate that mitigating action produces a noticeable difference in the timing and severity of drought experienced by the regions.

“Appropriate and feasible climate mitigation and adaptation plans are essential for overcoming the expected extraordinarily severe dry conditions”, explained Satoh. “Particularly regarding adaptation, it is crucial to improve our preparedness in the given time horizon before unprecedented drought conditions emerge.”