Global drought, one of the most complex and destructive natural phenomena, continues to escalate, threatening the environment, economies and billions of lives around the world. The latest findings from a large-scale research reveals a worrying increase in the severity of droughts worldwide, with an unexpected but critical factor contributing significantly to this intensification: atmospheric evaporative demand (AED).

The hitherto poorly understood impact of AEDs has emerged as a driver of catastrophic change. Research shows that AEDs increased drought severity by an average of 40 % at the global levelThis doesn't just mean that typically dry regions are becoming even drier; even areas previously considered humid are experiencing drying trends. It is alarming that over the last five years (2018-2022) areas affected by drought expanded by an average of 74 % compared to the period 1981-2017, while AED contributed to 58% of this increase. The year 2022 was a breakthrough, when moderate and extreme droughts affected 30 % of the total global land area, and 42 % of this extreme were attributed to the increased AEDThese findings suggest that the role of AED in intensifying drought is likely to continue under future warming scenarios.

The consequences of this trend are devastating. The scarcity of water, which is crucial for ecosystems, economic activities and human livelihoods, affects agriculture, energy, industry and domestic use, undermining the overall sustainability of societies. Drought has destructive effect on vegetation, reduces carbon uptake by ecosystems, causes widespread plant mortality and leads to significant disruptions to ecosystem functioning and biodiversity lossIt also negatively affects the productivity of annual and perennial crops, thereby exacerbates food insecurity and economic instabilityWith climate change, droughts are expected to become more frequent and intense, with increasing impacts on agricultural, environmental and hydrological systems.

Why is the AED so dangerous? AED intensifies water deficits by increasing evaporation, especially under conditions of low soil moisture. In addition, soil-atmosphere interactions can lead to positive feedback, where drying of soil and plants reduces latent heat fluxes, leading to an increase in temperature and AED, and thus to further intensification of the severity of the droughtAlthough there have been significant uncertainties in previous global drought assessments, this study provides a clearer picture by using a high-resolution global dataset. The researchers used an advanced Penman-Monteith model to calculate AED and the Standardized Precipitation and Evapotranspiration Index (SPEI), which effectively represents the supply and demand dynamics of drought through the difference between precipitation and AED.

Regional results are equally alarming. A significant contribution of AED to the negative SPEI trend (up to -0.06 units per year) was recorded in much of Europe, Asia, Australia, the western United States, and southern parts of South AmericaIn Africa and Australia, the impact of AED is particularly pronounced, contributing up to 65 % to drought trends between 1981 and 2022. In Europe, 2022 was a landmark year, with 82 % of land experiencing drought and 50 % under moderate to severe drought. Annual precipitation in Europe has fallen by up to 35 % below the 1981-2022 average and AED has increased by up to 40 %Not only are drier regions becoming drier, but previously humid areas are also experiencing drying trends due to the increase in AED.

These observations, supported by strong evidence, confirm that the drought is accelerating, especially in the last 5-10 years due to a sharp increase in AEDs directly related to global warmingGiven that anthropogenic global warming likely contributed to worsening global drought severity in 2022, there is an urgent need to develop better socio-economic and environmental adaptation measures to reduce the impacts of drought and improve global resilience to it. Without such action, the silent threat of drought will continue to grow, and with it its devastating consequences for the planet and humanity. Spring