Geosciences Column: The contribution of climate change to water scarcity in the MENA region

In this month’s Geoscience’s column, Alex Stubbings discusses the water scarcity problems in the Middle East and North Africa region and  the recent developments in modelling water resources here. 

The Middle East and North Africa (MENA) region is considered the most water-scarce region in the world. As such, the region faces a multitude of challenges in the 21^st century including population growth, economic development, food production and climate change. With these challenges in mind, a team of researchers led by hydrologist Dr. Peter Droogers explored how “Water resources trends in the Middle East and North Africa towards 2050” will change over the first half of the 21^st century. The study is published in EGU’s Open Access journal Hydrology and Earth System Sciences.

Presently, there exist huge spatial variations in water allocation, and the region as a whole is the driest and most water scarce region in the world. This is increasingly affecting the social and economic development of the region.  For example, the average water resource availability per capita is only marginally above the physical water availability of 1076 m³yr^-1, compared to the world average of 8500 m³yr^-1.

The prevailing arid conditions found within the area mean that over 85% of the MENA region can be considered desert. It follows that the region can be further subdivided into three distinct climate spaces: the Maghreb region, which constitutes North African countries with a Mediterranean climate, and is climatically heterogeneous; the Gulf Cooperation Countries located within the Middle East, and have a typical desert climate; and lastly, the Mashreq region, which includes countries that have a milder and wetter climate, such as Iraq and Syria.

The Middle East and North Africa (MENA) region (blue), (Source: Wikimedia Commons).

Therefore the lead question Droogers et al. focused on filling vital knowledge gaps. Indeed, they highlight that “a complete analysis on water demand and water shortage over the coming 50 year period based on a combined use of hydrological and water resource models, remote sensing and socio-economic changes has never been undertaken for the MENA region”. Moreover, they intend to achieve this by assessing water demand in the 22 MENA countries by taking into account the dynamics and uncertainties of climate change, demographic changes and economic development.

The team used two distinct models that covered a 50 year time period (2000–2050). Firstly, the PCR-GLOBWB (PC Raster Global Water Balance) hydrological model was run to determine the internal and external renewable water resources for present and future climate. And the second model employed was a water allocation model, referred to as the MENA Water Outlook Framework (MENA-WOF). This was chosen to analyse the linkage between renewable water resources and sectoral water demands, and utilises the Water Evaluation and Planning (WEAP) framework.

This approach allowed the research team to simulate the average hydrological conditions with great accuracy – best demonstrated by its ability to accurately model and replicate actual flows on the Blue Nile, White Nile and Atbora tributaries. The team singled this out as a key indicator of its robustness. They noted that other similar studies, to date, have yet to model these flow regimes accurately.

Long-term average annual observed and simulated flow (Source: Droogers et al., 2012).

Nevertheless, as with other empirical modelling studies the authors issue a caveat: that the results regarding water resources, derived through GCM output, should be interpreted with great care. The model predicts total water shortage will increase by 157 km³yr^-1, while water supply and demand are only projected to increase by 132 km³yr^-1.  In short, the overall trend is that all MENA region countries will see an increase in water shortages, as the increase in supply will not meet the growth in demand, except for Djibouti.

Droogers et al. naturally consider the contribution of climate change to water scarcity. Their results indicate that only 10% of the change in water demand will be attributed to climate change and the rest entirely due to socio-economic changes (under their average climate change scenario). Furthermore in the other two scenarios, wet and dry, socio-economic factors, again, are more important than the effects of climate change. However, they emphasise that despite the small contribution made by climate change its effects should still be taken into consideration when planning adaptation interventions.

The contribution of socio-economic changes and climate changes on total water demand in 2050 (Source: Droogers et al., 2012).

The findings presented here by Droogers et al. are unique. They have combined different data, models and tools in order to forecast changes in water demand and supply over a geographically diverse area. Despite this novel approach, a clear drawback of the study, recognised by the team, is that the spatial resolution is lower than the output for smaller geographical areas and utilising a single methodological approach would have allowed more in depth comparisons to be made between countries.

When looking at the wider landscape of climate change impacts and adaptation strategies the team refer to a World Bank study from 2010, which estimated the cost of adaptation for developing counties at 0.12% of GDP, with costs associated with adaptation increasing linearly with time. The authors offer a number of pragmatic solutions, which fall under the umbrella of ecological modernisation, highlighting the potential of desalination plants.

As a work in progress, Droogers and his team offer direction for future work. Firstly, they suggest that further research should be carried out at a higher spatial resolution, for instance, employing the same methodology but focusing on individual countries rather than on an entire region. And secondly, of the need to analyse potential adaptation strategies and the associated costs of implementing them within the region. Both directions have their merits, but with the uncertain nature of climate change makes it difficult to distinguish which step we should take next.

By Alex Stubbings