By Lynn R. Novelli
Significant drought conditions will develop across much of Europe before the end of the 21st century, brought on by a combination of climate change and man-made pressures on water supplies, according to new and unsettling research from the European Commission.
Such droughts as the one affecting this cornfield in Haute-Marne, France, are expected to become more prevalent by the end of the century, and even sooner in southern Europe, especially in the Iberian Peninsula, Italy, and the Balkan region, according to a new report. Wikimedia Commons/Isl@m
February 11, 2014—Early-stage drought conditions will develop across southern Europe as early as a decade from now, according to a recently released study from the European Commission's Joint Research Council (JRC); the study was conducted in partnership with the Center for Environmental Systems Research at the University of Kassel, in Germany.
The JRC study, "Ensemble Projections of Future Stream Flow Droughts in Europe," was published in the January 2014 issue of Hydrology and Earth Systems Science.
A team led by Giovanni Forzieri, Ph.D., a researcher of climate risk management at the JRC, and Luc Feyen, Ph.D., a JRC hydrologist, calculated the risk of drought across the European continent using a scenario analysis and a dozen integrated modeling tools. Together, these sophisticated predictive tools allowed them to quantify the predicted future greenhouse gas emissions and water consumption across different regions and by different economic sectors. The researchers examined, for example, the impact that would be generated by tourism, energy, manufacturing, irrigation and livestock, and other domestic activities.
"By using a large ensemble of climate projections originating from various combinations of 12 global and regional climate models, we capture a wide range of future climate developments and their variability," Feyen said in written responses to questions posed by Civil Engineeringonline. Climate and water-use models were then used to translate the greenhouse gas concentrations and water requirements into future climate and water projections.
On the basis of this robust modeling, the researchers concluded that the Iberian Peninsula, Italy, and the Balkan region will be hardest hit by drought conditions. "Drought conditions will intensify as the 21st century progresses, with up to a 40 percent reduction in minimum stream flow by the 2080s in [this area]," Feyen said. Stream flow is the velocity and volume of water in streams, rivers, and other channels and is a commonly used metric for evaluating water conditions ranging from flood to drought, he explained.
The total annual water withdrawals aggregated to a river basin scale for 1961 to 1990 are shown above. European Commission
Climate change caused by excessive greenhouse gas emissions that interferes with the normal water cycle will be the underlying cause for drought, Feyen said. "Greenhouse gas emission and water use …play a determinant role in describing future human influences that affect the global climate system and water demand," he said.
Excess greenhouse gases will create a combination of reduced rainfall—up to a 30 percent decrease across southern Europe—and increased surface evaporation caused by steadily rising temperatures, resulting in lower rates of groundwater aquifer recharging. The researchers predict a temperature increase of as much as 4° C in southern Europe in the summer and northern Europe in the winter.
The larger-scale changes that are expected to occur in precipitation and temperatures across the Iberian Peninsula, Italy, and the Balkan region compared with other regions in Europe, coupled with those regions' high seasonal water demand for crop irrigation, will make this region the most susceptible to drought, the models predict. Man-made pressures will exacerbate water-cycle issues in this region, Feyen said.
"Further globalization, innovation, and urbanization that exert pressure on water supplies, coupled with slow adoption of water-efficient technologies, will aggravate drought conditions by 10 to 30 percent in southern Europe," he said. The magnitude of what are called deficit volumes—the difference between an established threshold level of water use and reported levels—will be even more pronounced than changes in stream flow, he added. Such differences will result in as much as an 80 percent deficit in southern Europe by the 2080s, he said.
Stream flow droughts that develop in southern Europe will gradually intensify and expand geographically over time. The study's predictions include an expansion of drought conditions across most of southern and western Europe by the end of the 21st century, water deficit conditions spreading as far west as France.
The corresponding anticipated changes to total annual water withdrawals in the 2050s, according to modeling used in the study, are shown here. European Commission
The study paints a different picture for central and northern European countries. Over the same period, precipitation will rise by 10 to 20 percent in northern Europe and will be relatively stable in a transition zone between the southern and northern regions. The increased precipitation in northern Europe will drive an increase, or at least a less severe decrease, in minimum stream flows in the region.
"Scandinavia and the Baltic countries will experience a general increase in minimum flows of up to 20 percent—in some inland tributaries up to 40 percent—by the end of the 21st century," Feyen said. As a result, western, central, and northern European countries may experience a positive trend in their deficit volumes.
Although the JRC's predictions are important in and of themselves, the council's objective in conducting this in-depth analysis of future water cycle conditions in Europe was to initiate discussions about how to proactively manage those risks, Feyen stressed. "To plan suitable adaptation strategies, it is important for decision makers to know how drought conditions will develop at regional scales," he pointed out. "[The] results of this study emphasize the urgency of sustainable water resource management … to adapt to these potential changes in the hydrological system … to minimize the negative socioeconomic and environmental impacts. We are investigating possible adaptation strategies that society should take to efficiently face future climate change, including drought conditions."
The JRC researchers acknowledge that the addition of such water-management infrastructure as dikes and retention basins would have a significant chance of mitigating the drought risk, but they consider other strategies more desirable. In particular, the paper recommended "sustainable retention measures and improved water-use efficiency" as the preferred solutions.