Climate Change and Water Resources: Global and Local Impacts - PowerPoint PPT Presentation

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Climate Change and Water Resources: Global and Local Impacts


Climate Change and Water Resources: Global and Local Impacts – PowerPoint PPT presentation

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Title: Climate Change and Water Resources: Global and Local Impacts

Climate Change and Water Resources Global and
Local Impacts
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.

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
  • Reduced water supplies would place additional
    stress on people, agriculture, and the
  • Conflicts could be sparked by the additional
  • Improved water resource management can help to
    reduce vulnerabilities.

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

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

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

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

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

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

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

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

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
  • But
  • Result in smaller snowpack accumulations
  • Warmer climate likely result in earlier melt
  • Increase in winter or spring flows
  • May increase the risk of winter and spring floods

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
  • Increased wind and rainfall damage in regions
    prone to tropical cyclones

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

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

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

IPCC Freshwater resources and their management.
  • 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

IPCC Impacts on hydrology and water impacts
  • 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

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

Surface waters and runoff generation
  • Changes in river flows, lake and wetland levels
    depend on (climatic factors)
  • Changes in volume, timing and precipitation
  • 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
  • Lake size
  • Decreased due to human water use climatic
    factors (Lake Chad)

Leaf 'sweat glands (stomata) to worsen future
  • 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

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

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

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

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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.

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

Be sure to read
  • http//

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.

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

Climate change and water resources in the
  • http//
  • Status of fresh water resources in the
  • 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.

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.

  • 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
  • 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).

Saudi Arabia
  • Depletion of water resources due to climate
  • 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

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
  • 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

  • For graphics see http//
    nile_delta_potential_impact_o f_sea_level_rise

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

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
  • 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
  • British companies band together to tackle climate

  • 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
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