Water storage may see increase in West Asia and North Africa; solar geoengineering method worsens conditions, finds study
Terrestrial water storage is projected to decrease across the wetter lands around the Caspian and Mediterranean seas. Photo: iStock A recent study led by researchers from the European Geosciences Union, a non-profit international union in the fields of Earth, planetary, and space sciences, projected future water storage changes over the Mediterranean, Middle East, and North Africa in response to global warming and a climate intervention method aimed at mimicking planet cooling effects.
The researchers looked at West Asia (also known as Middle East) and North Africa (MENA) region, one of the most water stressed areas globally. This included the lands around the Caspian and Mediterranean seas, predicted to be highly vulnerable to future climate warming.
MENA is currently among the most water-stressed regions worldwide. The dry climate, intensifying droughts, increasing population and water over-extraction, particularly across West Asia, make it home to 12 of the 17 most water-stressed countries on the planet.
The scientists examined the effect of global warming on terrestrial water storage (TWS), which is all water on the land surface like snow, ice, water stored in vegetation, rivers and lake water and in the subsurface like soil moisture and groundwater.
TWS is projected to decrease across the wetter lands around the Caspian and Mediterranean seas to the north but increase over most of the MENA region, the paper found.
The Economics of Water Scarcity in MENA: Institutional Solutions, a report by the World Bank released last year, found that by the end of this decade, the annual per capita water availability will drop below the critical threshold of 500 cubic metres per person per year, indicating a state of absolute water scarcity.
It also predicted that by 2050, the region will require an additional 25 billion cubic metres of water per year to meet its demands.
Although MENA’s adjacent densely populated region — the Mediterranean — has better water storage, it is expected to suffer significantly from reduced water availability under future greenhouse gas climate scenarios. This is due to both expected significant decreases in rainfall and large increases in demand for irrigation water by the end of the twenty-first century.
The precipitation and water availability in the Mediterranean region, northwest of the MENA, are also expected to be highly sensitive to global warming, particularly water availability.
The study also looked at the impact of stratospheric aerosol intervention (SAI) in mitigation global warming effects in the region. SAI aims to mimic the planet cooling effects of volcanic eruptions by injecting sulphur dioxid directly into the stratosphere where it forms sunlight-reflecting sulphate aerosols, according to United States’ National Oceanic and Atmospheric Administration.
The study was the first attempt to understand the influence of greenhouse gas (GHG) emissions and SAI scenarios on both mean and extreme water storage changes over the lands around the Caspian and Mediterranean seas, West Asia and northern Africa compared to the historical 1985–2014 conditions.
The mean TWS is larger under SAI compared with just increases in GHG emissions, the paper further said. Changes in extreme water storage excursions under global warming are reduced by SAI.
Global warming, on the whole, decreases TWS extremes over all the study areas except for the Arabian Peninsula and western North Africa.
The most substantial reductions in extreme TWS resulting from global warming compared to historical norms — particularly in regions surrounding the Caspian Sea, Mediterranean, and eastern North America — were partly mitigated through SAI implementation, the study found.
A slight rise in extreme TWS in Iran and Iraq, projected due to GHG emissions, was more than offset by SAI. While SAI diminishes TWS in the Arabian Peninsula compared to the effects of global warming, this region is still anticipated to undergo the most significant increases in extreme water storage in the future, according to the study.
The study also noted a reduction in the mean TWS trend under both greenhouse gas and SAI scenarios, with extreme values also showing a decline compared to historical conditions.
The study was published in the journal Earth System Dynamics on January 29, 2024.
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