Climate Change and Water Resources: Global and Local Impacts

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Climate Change and Water Resources Global and
Local Impacts
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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
  dont involve massive dams, large-scale
  infrastructure, and tens or hundreds of billions
  of dollars.

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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.

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

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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

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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

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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

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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

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Precipitation frequency and intensity

• On average less frequent more intense ? floods
  and droughts consequences for water shortage
• Why?
• Local and regional rainfall rates greatly gt
  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)

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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
  -gt 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

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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

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Natural variability?

• Will not go away
• Water supplies can change dramatically, and for
  extended periods, even without anthropogenic
  climate change

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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

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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

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Water quality

• Flooding
• -gt 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
• -gt reducing dissolved oxygen concentrations
• -gt Cold-water species (salmon, trout) susceptible
  to warm-water temp
• ? increase salinity of surface water

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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

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Water demand

• Different rates of use in different climate zones
• UK a rise in temperature of 1.1 d C by 2025 -gt
  increase in average per capita domestic demand of
  ! 5 larger increase in peak demands
• Still
• rising water demands greatly outweigh greenhouse
  warming in defining the state of global water
  systems to 202

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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).

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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

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• Non-climatic drivers
• Current vulnerabilities correlated with climatic
  variability
• Particularly precipitation variability
• Particularly where?

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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)

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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

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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

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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

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Other impacts

• Climate change is killing US forests
• Mortality rates increased at an average of 3
  yearly

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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.

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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

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Be sure to read

• http//www.ipcc.ch/pdf/assessment-report/ar4/wg2/a
  r4-wg2-chapter3.pdf

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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.

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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

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Climate change and water resources in the
Mediterranean

• http//www.iucn.org/places/medoffice/Documentos/cl
  imate-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.

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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.

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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 US300 million
  (according to the Government sources).

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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

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Egypt Nile Delta

• 2.5 of Egypts 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

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Egypt

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

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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."

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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 Lebanons 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

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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