CLIMATE CHANGE AND WATER RESOURCES: GLOBAL AND LOCAL IMPACTS 1.

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 don’t 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 change4

Population demand for water

River flows ; groundwater quality

Wealth; equity access

Measures of stress5

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 future6

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 policy7

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?

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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 amount9

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

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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)

Evaporation and transpiration

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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

Changes in average annual runoff

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Importance? Depend on changes in temp and

precipitation Global message of increased

precipitation does not translate into regional increases in water availability

Natural variability?14

Will not go away Water supplies can change dramatically,

and for extended periods, even without anthropogenic climate change

Temperature, snowpack, and runoff

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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

Coastal zones16

IPCC (2001): sea-level rise1. Lowland inundation and wetland

displacement2. Altered tidal range in rivers and bays3. Changes in sedimentation patterns4. Severe storm surge flooding5. Saltwater intrusion into estuaries and

freshwater aquifers6. Increased wind and rainfall damage in

regions prone to tropical cyclones

Water quality17

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

Water storage18

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

Water demand19

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 warming in defining the state of global water systems to 202

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

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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

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 droughts26

Climate may already have had an impact on floods

Droughts affect: Rain-fed agriculture production Water supply for:

Domestic Industrial Agricultural purposes

Other impacts27

Climate change is killing US forests Mortality rates increased at an

average of 3% yearly

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Latest news29

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 quality30

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…31

http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter3.pdf

Status of Med32

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 change33

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 Mediterranean http://www.iucn.org/places/medoffice/Docu

mentos/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.

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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 US$300 million (according to the Government sources).

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Saudi Arabia37

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

Egypt: Nile Delta38

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

Egypt39

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

Latest IPCC report40

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."

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 an

d 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 Gr

owth

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

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Homework42

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