Water for people.pdf - WHO Thailand Digital Repository

T H E W O R L D ’ S W A T E R C R I S I S / 1 7Climate changeThe previous discussion has identified water scarcity, water quality andwater-related disasters as the main challenges facing the modernworld. As if these were not bad enough, the news is that things arelikely to get worse. Global circulation models of the atmospheresuggest that the increased carbon dioxide and other greenhousesgases are likely to cause changes to the global climate. It is generallyagreed that more precipitation can be expected from 30° North and30° South because of increased evapotranspiration. In contrast, manytropical and subtropical regions are expected to receive lower andmore erratic precipitation in the future. Indeed, the 2001 IntergovernmentalPanel on Climate Change report suggests that this mayalready be happening, and that ‘natural systems are vulnerable toclimate change, and some will be irreversibly damaged’ (McCarthyet al., 2001, p. 4). The effect of climate change on streamflow andgroundwater recharge varies regionally, but generally follows projectedchanges in precipitation. Impacts on ecosystems and on the availabilityof water resources for ecological and human needs will follow thesetrends.That there will be climate change in the future is no longer indoubt. What is far from clear is exactly what changes will takeplace, and the pace of change. All projections of future trends atregional and subregional levels carry strong warnings with respectto the uncertainties that lie ahead. Despite this, there is a generalconsensus that the many parts of the world already experiencingwater stresses (and likely to experience greater stress in the futureeven if rainfall patterns do not change) are the very ones whererainfall will be lower and more variable as climate change reallytakes hold. These include arid and semi-arid regions of thedeveloping world that are already poor and already have greatproblems in water resource management. The impact of climatechange is likely to make all of these problems worse.Climate change is also likely to lead to increased magnitude andfrequency of precipitation-related disasters – floods, droughts,mudslides, typhoons and cyclones. The 1990s saw a string of‘natural’ disasters. The 1998 monsoon season in South-East Asiabrought with it the worst flood in living memory to Bangladesh,placing some 65 percent of the country underwater, while HurricaneMitch wreaked devastation across Central America in the same year.In Venezuela in December 1999, following torrential rain that sawtwo years’ worth of rainfall in just two days, 15 million metres ofmud, rocks and trees detached themselves from the mountain sideand descended into the urban areas below killing 30,000 people. Theevent also caused approximately US$2 billion in damage (IFRC,2001). The same year saw the coast of Orissa in India devastated byone of the worst cyclones ever recorded, while early 2000 witnesseddevastating floods in Mozambique. These headline-catching eventsare just the tip of the iceberg: ‘The total number of disasters (notjust “great” ones) has also been on the rise, with the year 2000setting a new record’ (Abramovitz, 2001, p. 8).Flows in rivers and streams in many places are likely to decreaseat low flow periods as a result of increased evaporation. It is alsopredicted that climate change will degrade water quality throughincreased pollutant concentrations and loads from runoff andoverflows of waste facilities and due to increased watertemperatures. A recent study estimates that climate change actuallyaccounts for about 20 percent of the global increase in waterscarcity, the remaining 80 percent accounted for by populationgrowth and economic development. Countries that already sufferfrom water shortages, such as Pakistan, India, Mexico, northernChina and the countries of the Middle East and sub-Saharan Africawill be hardest hit (Vörösmarty et al., 2000).Interestingly, climate change has focused attention on the useof energy, and the intensity with which various forms of energygeneration emit greenhouse gases. Hydropower is able to make asignificant contribution to reducing the emission of such gases inenergy production. Currently, about 19 percent of the world’selectricity is produced from hydropower.The Development of InternationalWater PoliciesThe issues discussed in the previous sections have been graduallycoming into prominence over the past number of years, andattention has been given to them in the international debates onwater policies and management issues that have taken place overthe last decade or so, particularly since the Earth Summit in Rio deJaneiro. The history could even go back further, to the Mar del PlataAction Plan of 1977, but perhaps the best starting point is theDublin Conference of 1992, from which emerged the DublinStatement on Water and Sustainable Development that was acontribution to the preparation of the Earth Summit in Rio. Thisstatement contains much of merit, including the four DublinPrinciples that have become the cornerstone of much debate oninternational approaches to water policies:■ Freshwater is a finite and vulnerable resource, essential tosustain life, development and the environment.■ Water development and management should be based on aparticipatory approach, involving users, planners and policymakersat all levels.■ Women play a central part in the provision, management andsafeguarding of water.