The threat is very real: according to the United Nations desertification specialists, within just 15 years, the scarcity of water in arid and semi-arid places could displace some 700 million people on the planet, a figure that would multiply the number by 175 of refugees left so far by the current war in Syria. For its part, the UN Intergovernmental Panel on Climate Change (IPCC) warns of a greater risk of droughts, floods and forest fires in Europe, due to the effects of climate change.
The lack of water already affects 40% of the world’s population, a figure that could exceed 60% by 2050. In silence, without making headlines, droughts are spreading over more territories, leaving aridity and famines in their wake . Due to their socio-economic impact in the medium and long term, they are the most damaging natural disaster on the planet: they have generated direct losses of more than 70,000 million euros in the 20th century , and more than two million deaths between 1960 and 2014, according to data from the Catholic University of Louvain, in Belgium.
Global warming has become the best ally of this phenomenon, which will increase in the future. Without going any further, in Spain, especially in the southern half and the Levante, rainfall could drop by 30% by the end of the century, and temperatures rise on average to 4 ºC in winter and 6 ºC in summer. “Warming is likely to affect the frequency of droughts in Mediterranean regions.
Above all, those of short duration will increase ”, Gerardo Benito advances. This CSIC researcher participated together with more than eight hundred scientists in the writing of the latest IPCC report. The text recalls that we are directly responsible for these harmful transformations , since greenhouse gas emissions and other effects generated by human activity have accelerated the increase in temperatures.
“Spain is prepared to face short-term climatic droughts such as those pointed out by the IPCC,” says Benito, “but hydrological and agricultural droughts can be aggravated by the increase in water demand from the tourist and agricultural sectors, focused on deficit Mediterranean areas. of water”.
The main difference between these three types of droughts mentioned by Benito lies in their consequences. The climatic or meteorological begins as an atmospheric phenomenon that entails the temporary shortage of water, the result of the lack of rainfall in a given territory. The effects are gradually manifesting themselves in a reduction in available water resources –hydrological drought– and in a reduction in crops –agrarian drought–.
The Secretary General of the United Nations, Ban Ki-moon, encourages states to use preventive methods before damage strikes: “The cost of prevention is minimal compared to that of disaster relief. We must move from crisis management to drought prevention and resilience building. ” This last concept refers to the ability to adapt to adverse situations. The more resilient a region is, the less damage it will suffer and the greater the capacity it will have to cope with any extraordinary circumstances .
In the case of drought, resilience depends on the affected country having prevention methods, since some types of water shortages can be identified before they arrive, thanks to the weather forecast. As Antonio Mestre, head of the Area of Climatology and Operational Applications of the State Meteorological Agency (AEMET) explains, “medium-term prediction models are used for short-term droughts, and others for monthly and seasonal predictions, although these are less precise ” . These models make projections on average rainfall trends.
The IPCC uses other aids for its forecasts: climate models that generate scenarios on the average increase in dry spells over the next few decades. “You cannot make predictions about the occurrence of a drought in a specific year,” admits Benito. There are also statistical tools, such as the one created by the University of California at Irvine. Its Global Drought Monitoring and Prediction System (GIDMaPS) provides near real-time information and makes projections for up to three months, based on different rates of precipitation or humidity.
Early warning systems are very effective in prevention, since they evaluate the conditions of scarce rainfall in a region over a period of time and its effects on soil moisture. According to the World Meteorological Organization (WMO), one of the best of this type is the one developed by AEMET in Spain. This agency continuously monitors and evaluates the meteorological drought at the national level, with information that is updated monthly, based on the standardized precipitation index (SPI). This indicator represents the rainfall deviations from the mean in periods of one month to three years.
“Through the analysis of the SPI, AEMET collaborates in the assessment and early detection of drought; and it also carries out daily monitoring of soil moisture values for the entire national territory ”, reports Mestre. The daily update of this water balance makes it possible to generate maps of the amount of water available in the soil, in order to detect possible anomalies.
Another effective monitoring system is the American one, called NIDIS. “It works very well at the local level, but it fails in the coordination between the states of the country,” explains José Luis Camacho, scientific official of the WMO Agricultural Meteorology Division.
Looking back helps refine current analyzes. A group of scientists from the University of California at Irvine has measured the presence of heat waves and droughts in the United States in the last half century. Both phenomena occurred simultaneously with more frequency between 1990 and 2010, especially in the south and west of the country . “Our work helps to understand how the climate has changed in the past,” says Amir AghaKouchak, one of the authors of the research, published in the journal PNAS .
This scientist believes that the study of past climate events is the first step in creating mitigation plans for possible future damage. “Scientists should work with politicians to develop sensible strategies ,” proposes AghaKouchak.
This strategy for investigating what has already happened is applicable to Spain. A quarter of a century has passed since the drought that was one of the most important in our recent history and left hundreds of thousands of hectares dry. The phenomenon lasted for a long five years and caused the usual desalination plants in the Canary Islands to be transferred to the Mediterranean coast and the Balearic Islands , as an emergency measure to guarantee the water supply.
According to Ramón Llamas, emeritus professor at the Complutense University of Madrid and director of the Water Observatory, “the subsequent analysis showed that in periods of prolonged droughts – of more than three years – reservoir systems collapse. On the other hand, irrigators with groundwater have no problems ”. In his opinion, today the joint use of these waters and the alternative of those of the subsoil in times of scarcity has improved , “but not enough.”
The Spanish drought of the 90s showed that if there are years in which it rains less than normal, some regions, especially in the center, south and east of the country, run out of water to guarantee supply . “The weakness of our hydrological management system was revealed in the face of a great drought,” recalls Jorge Olcina, professor of Regional Geographic Analysis at the University of Alicante. A quarter of a century later, the Ministry of Agriculture, Food and Environment continues to be in command of the fight against this problem, but, as Camacho points out, “the management is carried out by the hydrographic confederations and some autonomous communities that have exclusive powers in this matter”.
This system was designed in the 80s, although in Spain we find similar historical examples: the Tribunal de las Aguas de la Vega in Valencia, which dates back to the times of al-Andalus, was a pioneer in the resolution of conflicts related to Water.
“There is culture, media and tradition, but we lack a national plan,” emphasizes Camacho. The experts consulted agree that the current National Hydrological Plan is not enough to manage droughts. “We cannot continue to offer the pitiful spectacle of the water wars every summer. If there are, it is because planning and management have not been done well, ”Olcina denounces.
Following international guidelines, this new plan should be based on water and territorial sustainability, which calls into question maintaining crops that require a lot of water but are not profitable , or transferring water to poorly planned developments and golf courses. It is estimated that a tourist consumes up to twice as much water as a regular resident, with the consequent imbalance that this generates in already deficient areas.
Another initiative that helps more efficient water management involves the use of treated water. “What good are they if we don’t take advantage of them to irrigate green areas, agricultural crops or golf courses?” Asks Olcina. Scientists recall that it is key to adapt societies to the most extreme climate that awaits us so that the harmful effects are minimal. ” The attempts are very timid in Spain and have been based on the promotion of alternative energies and the sustainable mobility of cities “, says this professor.
Not far from here, on the African continent, desertification is increasing at an increasing rate, and forecasts are pessimistic for the near future. The devastating earthquake and subsequent tsunami that hit the Indonesian coast in December 2004 claimed the lives of more than 200,000 people. Twenty years earlier, another much quieter misfortune wiped out 300,000. The country was Ethiopia, and the culprit was the 1983 drought.
Located between the Sahara desert and the Sudanese savannah, the Sahel is among the regions of the world that suffer the most from lack of water. However, recent water crises have hit Kenya and the Horn of Africa – Ethiopia, Somalia, Djibouti and Uganda the hardest. More than fifteen million people have suffered the recent food crisis that caused the continued lack of rain.
“Beyond the climatic factor, the conflicts in most of the countries of the Sahel and the Horn of Africa must be considered, which create instability, with thousands of homeless refugees, migrants and lack of food,” he declares from Dakar (Senegal) Emmanuel Seck, representative of Africa in the United Nations Convention to Combat Desertification and program manager of the African NGO ENDA. The lack of economic resources in that continent means that there are no basic infrastructures for water reserves , nor agricultural technology that allows crops to be more efficient, which leads to frequent famines.
