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Perspectives of the World’s Freshwater Resources under Global Change

Perspectives of the World’s Freshwater Resources under Global Change. Presentation by Olivia Roithmeier Part of the modul: Physical fundamentals of Global Change. www.geo.de. Content of presentation. Background facts Different driving forces (without climate change) Climate change effects

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Perspectives of the World’s Freshwater Resources under Global Change

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  1. Perspectives of the World’s Freshwater Resources under Global Change Presentation by Olivia Roithmeier Part of the modul: Physical fundamentals of Global Change www.geo.de

  2. Content of presentation • Background facts • Different driving forces (without climate change) • Climate change effects • Perspectives of fresh water resources under global change

  3. Our blue water planet earth • app. 1.4 billion km³ water: 96.5% in oceans  71% of earth surface • only 2.5% sweet water: • 69% stored in glaciers and ice coverings • 30% in underground groundwater • 0.3% surface sweet water (permafrost, lakes, swamps, rivers) • 0.001 % in the atmosphere • water distribution and state of aggregation is irregular in time and space due to it's physical-chemical characteristics and existing geographical conditions

  4. Mean annual precipitation on continents Lozan et al, 2006

  5. Distribution of water among continents • continental precipitation is higher than evaporation from continents, difference is runoff • app. 41.000 km³ H2O/yr transported into oceans by river's (28.000 km³ surface water, 13.000km³ groundwater) • mean duration of water vapor in the atmosphere: 10 days WBGU 1997

  6. (Sweet) water - Source of life on earth • besides air to breath most essential for living: all plants and animals need water for chemical-physical-physiological processes • combination “necessary for living but rare available“ makes water to a valuable resource: • 66% of extinct species were living in sweet water • provides important functions: • natural (e.g. necessary for life, space for living, transportation medium, earth formation by erosion) • cultural (e.g. food production, drinking, cleaning, use as energy exchanger, waste disposal)

  7. How to provide the demand? • actually app. 8% of this renewable resource sweet water used • 69% agriculture • 23% industry • 8% households • huge regional differences: 96% of industrial water used in North America and Europe • up to 40.000 embankment dams are employed; daily a new one build • all dams combined: fivefold the world river volume • three quarter of natural runoff is regulated anthropogenic in North America, North Asia and Europe • sediment transport has increased 5x by land use (app. 45 billion t)

  8. Water use per capita • daily water demand in Brandenburg approx. 90 l per day and capita (Märkische Allgemeine Zeitung, „Die Havel fließt rückwärts“, 01.08.2006) Lozan et al, 2006, changed

  9. Water stress: today • app. 33% of the world’s population in countries under ‘water-stress’ • app. 1 billion people without access to safe drinking water • 50% of developing countries suffering on water-related hazards • worldwide only 5% of house sewage cleaned developing countries: 90% of unclean water directly into surface waters • 21st century increasing population  changed patterns of water use  increase of future pressures on water • e.g. we consume 8 times more water than our grandparents did and with app. 8.5 billion peoples in 2025 we will have 1/3 sweet water less per capita

  10. Perspectives of sweet water availability Atlas der Globalisierung

  11. Important driver's effecting sweet water resources (without climate change) • population growth (provided same use per capita and year as 1990): • most increasing demand in Africa and parts of Asia (often ≥ 2x) • in North America, Oceania and China up to 40% • in South America up to 60% • in Europe mainly stable, partly decreasing • today more than 900 billion people chronically malnourished, will increase if global crop does not enhanced for 60% till 2010 • agriculture (provided no change in conditions of cultivation) • 2025: 18% increased water removal compared to 1995 (2x to 1970) • in spite of this increase, the proportion of agricultural water use will decrease on global scale to 56% = -19% compared to 1995

  12. Important driver's effecting sweet water resources (without climate change) • households: world-wide increase up to 2–3% with huge differences • high increase in Africa, Asia; decrease in Europe, South America • changed lifestyle linked with enhanced individual demand: today water demand in India 25l/capita/day; tourist centers around Mediterranean 1000l/capita/day • industry: triples till 2025, main reason of increasing water demand • even without climate change water stress is expected to increase, especially in Central Asia, North Africa, the drier parts of China

  13. Example: water stress and population growth • app. 1.4 billion people currently live in watersheds with less than 1000m³ water/person/year Schellnhuber et al 2006

  14. Water stress and climate change projections • WBGU-Analysis comparing the of actual water cycle with a simulated climate based upon doubled CO2-equivalent-content • in a warmer climate more precipitation will fall on land, especially in high latitudes and parts of the tropes and subtropes • in contrast, effected by lower precipitation will be big parts of Brasilia, South-West Africa, west and north of Australia • Conclusion • it seems that the anthropogenic climate changes will increase the water cycle, simultaneously there will be huge regional differences between who is how affected • climate change has the potential to increase water resource stress by increasing flood risk in some areas and increasing shortage risk in others

  15. Water stress and climate change projections • magnitude vary between climate models but consistency in: • many parts of the world: precipitation in winter fallen as snow will fall as rain whilst run off rapidly into rivers rather than be stored on the surface • runoff: increase in high latitudes of North America, Siberia, Eastern Africa, Eastern Asia while decrease in much of Europe, Middle East, Southern Africa, parts of North and Latin America • By the 2050s • increased water stress by climate change especially under A2 population growth in Europe, around the Mediterranean, parts of the Middle East, Central/Southern Africa, the Caribbean, parts of Latin and North America • “decrease“ in water stress by increased river flow in some regions but increased river flow mean not necessarily reduced water-related problems (higher flows occur during the high flow season increased flooding risk; without enough reservoir storage this “more“ water is not available for the dry season)

  16. WBGU WBGU 1997

  17. WBGU 1997

  18. Regional risks for hydrosphere • water shortage by increased demand/removal: Africa, parts of West Asia, North-West of China, parts of Pakistan and Mexico, West/South of India, western coast of USA and North-East Brasilia • overuse of ground water: e.g. Ogallala-Aquifers in USA • overuse of fossil ground water: e.g. Yemen, India, South East Asia • water discharges for irrigation: drying of the Aral lake or Everglades • salt water intrusion into deltas and coastal aquifers as consequence of overused ground and surface water: e.g. in Israel, China, Gulf of California • water shortage by decreasing quality of water • Africa salination, sedimental transport in rivers • North America and Europe  nitrate and biocides of agriculture (surface water eutrophication), contamination by industry (toxins, acidification) • South America  high bacterial/organic contamination • Middle East  salination by agriculture, salt water intrusion • East and South Asia  organically pollution, pesticides, eutrophication

  19. Effects of GHG mitigation on water stress • increase of 2°C above the 1961–1990 mean by 2055 • increased water stress for 500-1000 million (A1/B1 population projection), for 800-2200 million (A2 pop. proj.) and for 700-1100 million (B2 pop. proj.), depending on climate model • assumption of stabilization at 550 ppm: app. reduction of people faced with increased water stress by 15- 25% by 2025 and by 25-40% thereafter  These calculations are mean values on global scale not respecting the often substantial geographic variations!

  20. Perspectives of fresh water resources under global change • climate change: most important and geographically extensive physical driver • likely alter magnitude and timing of water stress • effects on water resources depend on spatial pattern and rate of climate change • several drivers (demographic, economic, social, physical) can change exposure to water related hazards, access to water, future water supply and thus influence changes in global water resources, too • 2050s: app. two times more would be adversely affected by climate change (under the most populous A2 population growth projections compared to the lowest) • climate policies reducing GHG emissions can reduce the impacts of climate change on water resources stresses without eliminating them • 550 ppm stabilization:reduces people adversely affected by climate change to 30-50% • one of the major future risk factors  increased demand of mega-cities and large population centers, e.g. in India and China (may have broad implications for environmental flows of water in major rivers of China, India and Tibet)  The impact of climate change on future water resource availability depends to a very large extent on the future state of the world and particularly on the numbers of people potentially exposed to water shortage.

  21. Some ways out of water crisis • increasing awareness for this problem and possible solutions, incl. that everyone can and must change behavior, not only industry • increasing efficient use of water (e.g. removed water: 55% used and 45% loss by transport or evaporation) including technical and knowledge transfer to implement this • increase re-use of water and diminish first use • improved supply with “healthy“ water • adaptation to changed (time and space) precipitation pattern • if water is used by more than one state (intercontinental lakes, sea, rivers) the states must cooperate with each other to prevent water conflicts escalating

  22. Sources of literature • Schellnhuber et al., 2006_Avoiding dangerous climate change • Lozan et al., 2006_Enough water for all ? • WBGU 1997_Wege zu einem nachhaltigen Umgang mit Süßwasser • Atlas der Globalisierung, Le Monde diplomatique, 2006_Sauberes Wasser – knappes Gut www.geo.de, aurora/laif

  23. Comments for Olivia Roithmeierfrom Manfred Stock • To be finished .....

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