<<

cover article

Peak – Entering an Era of Sharpening Water Shortages Photo: GettyPhoto: Images

A new concept, “” has emerged. It indicates that the era of easy access in “severe water shortage”. By combining to blue water is coming to an end in many of the world. Expanding water these two dimensions it has been shown pollution, depleted river streamflow, overdrawn , water usability that 1.4 billion people are already living in threatened by salinisation, and water for ecosystems sinking below the acceptable over-appropriated areas. 1.1 billion of these minimum all point to a peaking of blue water , a theme highlighted in people live in areas that are also suffering “The World’s Water 2008-2009” from the Pacific Institute. Green under severe water shortage. In such areas, t h r o u g h s o i l a n d l a n d d e g r a d a t i o n h a s b e e n d i s c u s s e d a s d r o u g h t a n d d e s e r t i fi c a - demand management will not be enough. tion. Human ingenuity, coping strategies and fundamental rethinking on water These areas will require import to achieve management are urgently needed to mitigate the drivers of peak water and adapt security. to their effects on freshwater and natural resources. For each aspect of water scarcity, the populations affected are expanding. Fol- Borrowing momentum from the regions but covers over 15 percent of all lowing predictable change, it can debate, the peak water concept has appeared continental . in environmental texts predicting that as fu- Blue water scarcity has conventionally What is Blue and Green Water? ture demand for water grows its availability been conceptualised by addressing use- Blue water is the visible water contained in in many places will shrink. The term itself to-availability ratio – also called critical- rivers and . Green water refers to is a new and apt name for the present and ity ratio. The usual recommendation is the invisible water in the , which com- looming threat of amplified water scarcity of for water demand management to bring prises a huge but often forgotten portion both blue and green water sources occurring down over appropriation. The relative of . Both sources originate around the world. amount that should remain unallocated from the rainfall captured within the water to maintain aquatic ecosystem health has divide of the catchment. Climate defines Blue Water Scarcity Mounts been specified as “environmental flow”. the constraints to human activities in At the 2008 World Economic Forum in The dimension of the unal- terms of evaporative demand, droughts, Davos, Switzerland, water scarcity attract- located flow is frequently neglected but dry spells, rainfall seasonality and vari- ed considerable concern. A CEO Water poses a serious problem for both human ability. The roots catch the infiltrated , Mandate was formulated with the aim to and ecosystem health. which supports production and veg- assess the level of water insecurity and its As population increases, a second di- etation covers in , and influence on future economic wealth and mension of blue water scarcity has to be croplands, and which transpires back to political security. The International Water taken into account. The population pres- the atmosphere. Runoff, resulting from Management Institute (IWMI) has shown sure on the available water, or the level of the climate, topography and the ability of that a man-made blue water scarcity, mani- water crowding, is a phenomenon referred the to absorb the rain impact the con- fested in terms of river basin closure, is a to as “chronic water shortage”. When com- sumptive water use of the . problem developing mainly in irrigated bined with high water stress this results

10 be foreseen that by 2050, depending on Governance Implications Water and the Planet’s Support the rate of fertility decline, the popula- Today’s water crisis is seen as a crisis of System tion in with chronic water short- management, not a crisis of water shortage. The global change debate is now raising con- age (above 1,000 people per million cubic Many international organisations mainly cerns. At the recent Tällberg Forum in Swe- meters per year) will be 3 to 5.5 billion. focus on blue water and are more concerned den, the possibility of formulating planetary Looking at the other dimension of blue with water stress caused by high use-to- constraints for human activities was analysed. water scarcity, expressed as use to availabil- availability ratios than with chronic blue As the is central in the operation ity ratio, the population in countries with water shortages. of the global life-supporting system, deter- high water stress (more than 40 percent use Tomorrow’s water resources manage- a maximum blue water withdrawal to to availability) may rise to between 4.5 and ment will have to address green and blue safeguard a minimum river streamflow was 7 billion people. water together with the strong link be- one of the ten items under discussion. tween land and water. This is especially Water shortages are mounting while Green Water Scarcit y and Food Securit y critical in the semiarid tropics where demand and consumption rapidly acceler- Green water may also be scarce in differ- poverty, under nutrition and population ate. The urgency of this situation can not ent ways. This to problems for food growth dominate. In , a long se- be overstated. Yet, the need to anticipate, production, especially in semiarid regions. quence of drought years linked to climate prevent, mitigate and adapt to this reality Green water in the soil is exposing quantita- change is causing both green and blue and potential “peak water” remain either tive deficiency in vulnerable regions. Man- water shortages and revealing the needed poorly understood or greatly underestimated. made green water scarcity, which results shift towards a blue/green and land/water Measures to control the massive driving forces in conventionally called integrated approach. behind global warming, population growth desertification, a phenomenon that has re- Humans are exerting multiple pressures and economic development that rapidly ac- mained high on the political agenda since on the freshwater resources. Population celerate unquenchable demand for water must the 1970’s. Natural green water scarcity in growth, economic development, increas- be crafted. Water resources management will semiarid regions is caused by a lack of rain, ing water demands, increasing water pol- have to address the original – precipi- which may, but may also not, increase with lution, increasing food expectations and tation –to steer land and water-related human . climate change are squeezing from all activities that are compatible at the basin level Problems of green water deficiencies fronts. Future water resources governance and strive towards hydrosolidarity. caused by meteorological factors, (i.e. lack must sharpen its tools to avoid approach- of rain) can be met by in areas that ing tipping points that would unbalance By Prof. Malin Falkenmark, SIWI do not also suffer blue water shortages. In a peaceful world. email: [email protected] situations where the deficiency is manmade and land degradation has left the root zone too dry to meet the water needs of crops, the deficiency can be mitigated through soil and . The way forward may be “triple green” : green water based, green for increased production – like was seen in the “green revolution” in agri- culture – and green in the sense of being environmentally sound. Globally, producing food for the grow- ing world population will be challenging. By mid-century, half of the world popula- tion may live in countries where national food self-sufficiency – generally preferred by politicians to avoid the risk of food riots – is impossible. Food trade will therefore be essential to eradicate hunger. If fertility decline would follow the slow route, world food trade would have to double by 2050. In low-income countries, where purchasing power is low, cropland expansion will have to be accepted to make a decent level of possible. Food production ambitions might be lowered, for instance by avoiding unneces- sary food losses from field to fork (see article pages 12-13). If 2200 kcal/p day would be considered enough, at least half of this huge

future water deficiency would be covered. Photo: Mats Lannerstad Many countries would still, however, re- By 2050, the population in countries with chronic water shortage (above 1,000 people per main import dependent. million cubic meters per year) may be 3 to 5.5 billion.

11