Climate Change and Water Resources: Global and Local Impacts

1. Climate Change and Water Resources: Global and Local Impacts

2. Situation now.. • Global Water Crisis • Over 1 billion people don't have access to clean drinking water; more than 2 billion lack access to adequate sanitation; and millions die every year due to preventable water-related diseases. • 5 million people – mainly children – die every year from preventable, water-related disease is surely one of the great tragedies of our time. • over 34 million people might perish in the next 20 years from water-related disease • hundreds of billions of dollars are needed to bring safe water to everyone who needs it. Since international water aid is so paltry, many of these experts claim that privatization of water services is the only way to help the poor. • are solutions to the global water crisis that don’t involve massive dams, large-scale infrastructure, and tens or hundreds of billions of dollars. …

3. Water and Climate Change • Climate change will lead to more precipitation - but also to more evaporation • Precipitation will probably increase in some areas and decline in others. • Changing precipitation patterns will affect how much water can be captured. • The drier the climate, the more sensitive is the local hydrology. • High-latitude regions may see more runoff due to greater precipitation. • The effects on the tropics are harder to predict. • Reservoirs and wells would be affected. • New patterns of runoff and evaporation will also affect natural ecosystems. • Rising seas could invade coastal freshwater supplies. • Reduced water supplies would place additional stress on people, agriculture, and the environment. • Conflicts could be sparked by the additional pressures. • Improved water resource management can help to reduce vulnerabilities.

4. Drivers of change River flows ; groundwater quality Population demand for water Wealth; equity access

5. Measures of stress • Indicators of exposure • Numbers affected by flood / drought • Indicators of access • Numbers with access to safe water • Indicators of availability • Resources per capita

6. Estimating the future • Future impacts depend on future climate and future exposed population • Simulate water availability using a macro-scale hydrological model • Construct climate change scenarios from global climate models • Construct consistent scenarios for change in exposed population

7. Effects of climate policy • Rescale changes in runoff to different global temperature changes • Calculate water stress indicators for different temperature increases • “2 degree C target” • ~0.8 degrees C above 1961-1990 mean by 2020 • ~1.2 degrees C above 1961-1990 mean by 2050

8. What to look for specifically? • Precipitation amount • Precipitation frequency and intensity • Evaporation and transpiration • Changes in average annual runoff • Natural variability • Snowpack • Coastal zones • Water quality • Water storage • Water demand

9. Precipitation amount • Will increase as global temperatures rise • Evaporation potential will increase because warmer atmosphere can hold more moisture • For a one-degree Celsius increase in air temperature, the water-holding capacity of the atmosphere increases by 7 percent • What goes up – must come down • How much global average precipitation will increase? Not so certain • Models suggest: 1-2 percent per degree Celsius • Does not mean it will get wetter everywhere and year-round; some get less; some get more • More rain over high-latitude land areas; less over equatorial regions;

11. Precipitation frequency and intensity • On average: less frequent; more intense  floods and droughts; consequences for water shortage • Why? • Local and regional rainfall rates greatly > evaporation rates and depend on the convergence of regional to continental scale moisture sources • Rainfall intensity should increase at same rate as increases in atmosphere moisture (7% / degree C)

12. Evaporation and transpiration • evapotranspiration: • From open water, soil, shallow groundwater, water stored on vegetation • Transpiration through plants • Consistent prediction: increase total evaporation • One study: an increase/decrease in precipitation of 20%  runoff changing by ~ 20%; w/ no change in precipitation, a 2 degree C increase in temp -> reduce mean annual runoff by 4 to 12%. Thus – if temp increased by 4 degree, precipitation would need to increase by 20% to maintain runoff

13. Changes in average annual runoff • Importance? • Depend on changes in temp and precipitation • Global message of increased precipitation does not translate into regional increases in water availability

14. Natural variability? • Will not go away • Water supplies can change dramatically, and for extended periods, even without anthropogenic climate change

15. Temperature, snowpack, and runoff • Very likely that a greater portion of winter precipitation will fall as rain rather than snow • An increase in rain events would increase winter runoff • But • Result in smaller snowpack accumulations • Warmer climate likely result in earlier melt season • Increase in winter or spring flows • May increase the risk of winter and spring floods

16. Coastal zones • IPCC (2001): sea-level rise • Lowland inundation and wetland displacement • Altered tidal range in rivers and bays • Changes in sedimentation patterns • Severe storm surge flooding • Saltwater intrusion into estuaries and freshwater aquifers • Increased wind and rainfall damage in regions prone to tropical cyclones

17. Water quality • Flooding… • -> increased sediment and non-point source pollution loadings in watercourses • Decline in streamflows and lake levels … •  nutrients and contaminants become more concentrated in reduced volumes with longer water residence times • -> reducing dissolved oxygen concentrations • -> Cold-water species (salmon, trout) susceptible to warm-water temp •  increase salinity of surface water

18. Water storage • Tradeoff between storing water for dry-period use and evacuating reservoirs prior to the onset of the flood season to protect downstream communities

19. Water demand • Different rates of use in different climate zones • UK: a rise in temperature of ~ 1.1 d C by 2025 -> increase in average per capita domestic demand of ! 5% + larger % increase in peak demands • Still • rising water demands greatly outweigh greenhouse warmingin defining the state of global water systems to 202

20. IPCC: Freshwater resources and their management. 2007 • The impacts of climate change on freshwater systems and their management are mainly due to the observed and projected increases in temperature, sea level and precipitation variability (very high confidence) • Semi-arid and arid areas are particularly exposed to the impacts of climate change on freshwater (high confidence). • Higher water temperatures, increased precipitation intensity, and longer periods of low flows exacerbate many forms of water pollution, with impacts on ecosystems, human health, water system reliability and operating costs (high confidence). • Climate change affects the function and operation of existing water infrastructure as well as water management practices (very high confidence). • The negative impacts of climate change on freshwater systems outweigh its benefits (high confidence).

21. IPCC: Impacts on hydrology and water impacts (2001) • Variation in streamflow and groundwater recharge regionally and between scenarios • Early snowmelt – therefore… • Degraded water quality • Increase in flood magnitude and frequency • Increased demand for water (pop. growth & economic development) globally • High vulnerability in unmanaged systems

22. Non-climatic drivers… • Current vulnerabilities correlated with climatic variability • Particularly: precipitation variability • Particularly where?

23. Surface waters and runoff generation • Changes in river flows, lake and wetland levels depend on (climatic factors): • Changes in volume, timing and precipitation intensity • Changes in temperature, radiation, atmospheric humidity, and wind speed: • Potential evapotranspiration offset small increases in precipitation  further effect of decreased precipitation on surface waters • Increased atmospheric carbon dioxide [ ] • Alters plant physiology  affecting evapotranspiration • Lake size • Decreased – due to human water use + climatic factors (Lake Chad)

24. Leaf 'sweat glands‘ (stomata) to worsen future flooding • Regulate the amount of carbon dioxide taken up by the plants during photosynthesis • Absorb and release moisture during transpiration • Tend to shrink when carbon dioxide levels rice • So – plants transpiring less  plants consume less water  more water remains in the soil  more water runs into the river • River flow increased by 3% worldwide • In the Med and South American: might ease the damage from drought; Not so in Asia, Europe, and North America

25. Groundwater • Respond slower than surface water systems • Correlate more strongly w/ precipitation than w/ temperature • Temperature more important for shallow aquifers • Temperature more important in warm periods

26. Floods and droughts • Climate may already have had an impact on floods • Droughts affect: • Rain-fed agriculture production • Water supply for: • Domestic • Industrial • Agricultural purposes

27. Other impacts • Climate change is killing US forests • Mortality rates increased at an average of 3% yearly

29. Latest news • Autumn rain down 90 percent in China rice belt • BEIJING (Reuters) - Large areas of south China are suffering from serious drought, with water levels on two major rivers in rice-growing provinces dropping to historic lows, state media said on Tuesday. • Bangladesh says reaches all cyclone-hit areas • DHAKA (Reuters) - Relief workers and the Bangladesh military on Tuesday reached the last remaining pockets of the country devastated by a cyclone that killed nearly 3,500 people along the Bay of Bengal.

30. Water quality • Lakes and reservoirs: climate change effects primarily due to water temp. variations (climate change or thermal pollution) •  oxygen regimes, redox potentials, lake stratification, mixing rates, biota development •  diseases – via drinking water or via consuming crops irrigated with polluted water • ¼ of global pop lives in coastal regions: water-scarce + rapid pop growth •  sea-level rise  increased saline intrusion  reduction in freshwater availability

31. Be sure to read… • http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter3.pdf

32. Status of Med • Fresh water resources in the Mediterranean are under increasing pressure in terms of both quantity and quality. • Northern Mediterranean countries with higher, more regular rainfall also face climate-induced natural hazards, flooding and water shortages in basins susceptible to periodic drought. As a consequence, human and natural systems sensitive to water availability and water quality are increasingly stressed, or coming under threat. Those countries will have to face water quality degradation and meet the increasing needs of environmental protection and restoration. • In South and East Mediterranean counties where use is now approaching hydrological limits, and the combined effects of demographic growth, increased economic activity and improved standards of living have increased competition for remaining resources. Water resources are already overexploited or are becoming so with likely future aggravation where demographic growth is strong. The Eastern countries will be more sensitive to short term or structural shortages, in certain areas.

33. IPCC: Mediterranean nations face up to threat of climate change • Global warming threatens to wreak economic havoc across the Mediterranean basin • IPCC 2007 reports issued in February and April: Mediterranean basin would be hit especially hard by mounting temperatures, which are predicted to rise globally by 1.8 to 4.0 C (3.2 to 7.2 F) by the end of the century • Threatened by rising seas: • Nile River Delta • Venice • Tunisian island of Jerba

34. Climate change and water resources in the Mediterranean • http://www.iucn.org/places/medoffice/Documentos/climate-change-mediakit_EN2.pdf • Status of fresh water resources in the Mediterranean • Fresh water resources in the Mediterranean are under increasing pressure in terms of both quantity and quality. • Northern Mediterranean countries susceptible to periodic drought. • In South and East Mediterranean counties –water resources already overexploited; more sensitive to short term or structural shortages.

35. Mediterranean vulnerability to climate change • greater variability and extreme weather events, wetter winters and drier summers and hotter summers and heat waves. • affect the water demand, quality and watershed. • Pollution will be intensified by runoff • floods which will be higher and more frequent. • The changes in the frequency of extreme events might be the first and most important change registered in the Mediterranean.

36. Algeria.. • Significant exposure to recurring natural hazards (e.g., floods, earthquake, drought) emphasises the vulnerability of the poor population because of the recurring social, financial and economic losses. • On November 2001, severe rains accompanied by floods and mud-flows affected 14 villages in the northern part of Algeria. • Damage and loss of property were considerable across sectors, amounting to about US$300 million (according to the Government sources).

37. Saudi Arabia • Depletion of water resources due to climate change • Ground water levels dropping very quickly • Overall temperature increase of 0.5 to 2 degrees Celsius in desert regions between 1976 and 2000. • Many deserts will experience a decline of 5 to 10 percent in rainfall in the near future • Restrict irrigation agriculture

38. Egypt: Nile Delta • 2.5% of Egypt’s land area (Nile delta and Nile valley) suitable for intensive agriculture • 50 km wide land strip less than 2 m above sea-level • Erosion of sand belt – increased since Aswan dam • Rising sea level… • Change the water quality • Affect more fresh water fish • Flood agricultural land • Endanger recreational tourism • Salinate essential groundwater

39. Egypt • For graphics see: http://maps.grida.no/go/graphic/nile_delta_potential_impact_o f_sea_level_rise

40. Latest IPCC report • There is high confidence that by mid-century "many semi-arid areas, for example the Mediterranean basin, western United States, southern Africa and northeast Brazil, will suffer a decrease in water resources due to climate change."

41. Readings – a lot, yes • Climate Change 2001: Working Group II: Impacts, Adaptation and Vulnerability, Intergovernmental Panel on Climate Change, (IPCC, 2001): • Chapter 4 - Hydrology and Water Resources • Chapter 6 - Coastal Zones and Marine Ecosystems • Chapter 18 - Adaptation to Climate Change in the Context of Sustainable Development and Equity • and from: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change: Chapter 3 - freshwater sources and their management   • Climate change puts sea at risk • Tropical cyclones in the Mediterranean? • Global Water Resources: Vulnerability from Climate Change and Population Growth • Climate Change and Water Resources: A Primer for Municipal Water Providers • and, on Lebanon, The Impacts of Climate Change on Water Resources of Lebanon-Eastern Mediterranean  and for Lebanon’s policies on water Drought, Thirst, and Hunger.” (in Arabic). Al-Adab Magazine. September 2007. and, some other climate change news: • Other readings: • Friday, November 23rd, 2007: “We Are Now In The Danger Zone”: Leading Australian Scientist Tim Flannery on Climate Change and How To Save the Planet • British companies band together to tackle climate change

42. Homework • By Friday. Via Email. • 2 page paper (no less, no more) on impact of climate change on water resources of any country in the region (either Med or Arab world) • Or • Summary of methodology of understanding impact of climate change on water resources • Reference correctly