An overview of the world's water resources problems in 2050

The French Academy of Sciences published in October 2006 a “Science and Technology Report” entitled “Continental Waters”, which was prepared by the Academy for the French Government, to examine some of the perceived maj or water problems that will face the World towards the middle of the present century. The aim of this report, written by a panel of contributors, members and non-members of the Academy, was to determine the possibility of major crises occurring in the World due to water-related problems, and to suggest possible actions to anticipate such crises.The perceived potential risks were linked to climate change consequences for water resources availability, to the increase of the World's population, to the impact of society on water ecosystems, to potentially deteriorating drinking water quality, and to the increasing number of mega-cities (with more than ten million inhabitants) mostly in the developing world.The paper focuses on the major findings of this report, i.e. the consequences of the increase of the World's population, estimated to be in the range 8 – 10 billion inhabitants by 2050, and the likely consequences of climate change, for both average and extreme events. The available solutions for feeding a larger population are reviewed, and irrigation, rain-fed agriculture, and improvement of the efficiency of water use are discussed. The potential for competition between food production and bio-energy production is also examined. The most likely scenario is a drastic increase in rainfed agriculture on some continents (South America, Africa), at the expense of forest and natural virgin land, and the strong dependence of other continents (Asia, North Africa and the Middle East) on importated of food products.Finally, the risk of a global food shortage in case of severe droughts (e.g. during very strong El Nińo events) in large portions of the Globe is discussed.