Impact of Climate Change 1Impact of Climate Change 1

Emilia JinEmilia Jin

Lecture21: Nov 11, 2008

CLIM 101: Weather, Climate and Global Society

IPCC AR4 Working Group II Report IPCC AR4 Working Group II Report "Impacts, Adaptation and "Impacts, Adaptation and

Vulnerability"Vulnerability"• Chapter 3 - Impacts on Fresh Water Resources and their Management

• Chapter 4 - Impacts on Ecosystems, their Properties, Goods and Services

• Chapter 5 - Impacts on Food, Fibre, and Forest Products

Climate and Non-climate Drivers of ChangeClimate and Non-climate Drivers of Change

coping range of climate: the capacity of systems to accommodate variations in climatic conditions

Climate and Non-climate Drivers of ChangeClimate and Non-climate Drivers of Change• Climate drivers: Temperature and precipitation, and their variability on all timescales from days to the seasonal cycle to interannual variations

• Non-climate drivers such as urbanisation and pollution can influence systems directly and indirectly through their effects on climate variables such as albedo and soil-moisture regimes. Socio-economic processes, including land-use change (e.g., forestry to agriculture; agriculture to urban area) and land-cover modification (e.g., ecosystem degradation or restoration) also affect multiple systems.

The SRES global storylines and scenariosThe SRES global storylines and scenarios

The SRES global storylines and scenariosThe SRES global storylines and scenarios

Percentage change in cropland area by Percentage change in cropland area by 20802080

Fresh Water Resources and Fresh Water Resources and their Managementtheir 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.

• Semi-arid and arid areas are particularly exposed to the impacts of climate change on freshwater.

• 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.

• Climate change affects the function and operation of existing water infrastructure as well as water management practices.

• Adaptation procedures and risk management practices for the water sector are being developed in some countries and regions (e.g., Caribbean, Canada, Australia, Netherlands, UK, USA, Germany) that have recognized projected hydrological changes with related uncertainties.

•The negative impacts of climate change on freshwater systems outweigh its benefits.

How human activities affect freshwater How human activities affect freshwater resources (both quantity and quality) and resources (both quantity and quality) and

their management?their management?

• Water is indispensable for all forms of life.• Climate and freshwater systems are interconnected in complex ways.

• There are apparent trends in streamflow volume, both increases and decreases, in many regions.

• The effect of climate change on streamflow and groundwater recharge varies regionally and between scenarios, largely following projected changes in precipitation.

• Peak streamflow is likely to move from spring to winter in many areas due to early snowmelt, with lower flows in summer and autumn.

• Glacier retreat is likely to continue, and many small glaciers may disappear.

• Generally, water quality is likely to be degraded by higher water temperatures.

• Flood magnitude and frequency are likely to increase in most regions, and volumes of low flows are likely to decrease in many regions.

The state of knowledge of climate change The state of knowledge of climate change impactsimpacts

on hydrology and water resources was on hydrology and water resources was presentedpresented

The state of knowledge of climate change The state of knowledge of climate change impactsimpacts

on hydrology and water resources was on hydrology and water resources was presentedpresented

• Globally, demand for water is increasing as a result of population growth and economic development, but is falling in some countries, due to greater water-use efficiency.

• The impact of climate change on water resources also depends on system characteristics, changing pressures on the system, how the management of the system evolves, and what adaptations to climate change are implemented.

• Unmanaged systems are likely to be most vulnerable to climate change.

• Climate change challenges existing water resource management practices by causing trends not previously experienced and adding new uncertainty.

• Adaptive capacity is distributed very unevenly across the world.

Observed Climate-related TrendsObserved Climate-related TrendsCurrent Sensitivity and Vulnerability

Current Vulnerabilities of Freshwater Current Vulnerabilities of Freshwater Resources Resources

and their Managementand their Management

Key Future Impacts and Key Future Impacts and VulnerabilitiesVulnerabilities

•Surface waters

•Groundwater

•Floods and droughts

•Water quality

•Erosion and sediment transport

Changes in Average Annual Runoff: 2050s Changes in Average Annual Runoff: 2050s A2A2

Change in Annual Runoff: 2041-60/1900-70Change in Annual Runoff: 2041-60/1900-70

Annual Diffuse Groundwater Recharge: 2041-2070/1961-90

Change in the Recurrence of 100-year Change in the Recurrence of 100-year DroughtsDroughts

Costs of climate change in Okanagan, Costs of climate change in Okanagan, CanadaCanada

Cross-Scale Issues in the Integrated Water Cross-Scale Issues in the Integrated Water Management of Colorado River BasinManagement of Colorado River Basin

Some adaptation options for Some adaptation options for water supply and demandwater supply and demand

Limits to Adaptation and Adaptive Limits to Adaptation and Adaptive CapacityCapacity

• Physical limit

• Economic constraints to what is affordable

• Political or social limits to the implementation of adaptation measures

• The capacity of water management agencies and the water management system as a whole may act as a limit on which adaptation measures (if any) can be implemented.

Implications for Sustainable Implications for Sustainable DevelopmentDevelopment

Millennium Development Goals (MDGs)

Future Climate Change Impacts on Future Climate Change Impacts on FreshwaterFreshwater

Fresh Water Resources and Fresh Water Resources and their Managementtheir 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.

• Semi-arid and arid areas are particularly exposed to the impacts of climate change on freshwater.

• 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.

• Climate change affects the function and operation of existing water infrastructure as well as water management practices.

• Adaptation procedures and risk management practices for the water sector are being developed in some countries and regions (e.g., Caribbean, Canada, Australia, Netherlands, UK, USA, Germany) that have recognized projected hydrological changes with related uncertainties.

•The negative impacts of climate change on freshwater systems outweigh its benefits.

Ecosystems, their Properties, Goods and Ecosystems, their Properties, Goods and ServicesServices

• During the course of this century the resilience of many ecosystems (their ability to adapt naturally) is likely to be exceeded by an unprecedented combination of change in climate, associated disturbances (e.g., flooding, drought, wildfire, insects, ocean acidification) and in other global change drivers (especially land-use change, pollution and over-exploitation of resources), if greenhouse gas emissions and other changes continue at or above current rates.

• Several major carbon stocks in terrestrial ecosystems are vulnerable to current climate change and/or land-use impacts and are at a high degree of risk from projected unmitigated climate and land-use changes.

• Approximately 20 to 30% of plant and animal species assessed so far (in an unbiased sample) are likely to be at increasingly high risk of extinction as global mean temperatures exceed a warming of 2 to 3°C above preindustrial levels.

•Substantial changes in structure and functioning of terrestrial ecosystems are very likely to occur with a global warming of more than 2 to 3°C above pre-industrial levels.

•Substantial changes in structure and functioning of marine and other aquatic ecosystems are very likely to occur with a mean global warming of more than 2 to 3°C above preindustrial levels and the associated increased atmospheric CO2 levels.

• Ecosystems and species are very likely to show a wide range of vulnerabilities to climate change, depending on imminence of exposure to ecosystem-specific, critical thresholds

Major Ecosystems Addressed in this Major Ecosystems Addressed in this reportreport

• 2003

• Heat wave hits

Europe

• 30,000 people die

in Western EuropeobservationsHadCM3 Medium-High (SRES A2)

2003

2040s

2060sT

emp

erat

ure

an

om

aly

(wrt

196

1-90

) °

C

GEC is more acute than everGEC is more acute than ever

Schär et al. 2004

Rebetez et al. 2006 August 2003

Precipitation Max. temperature

• Heat stress• Drought stress• Wildfires

Ecological impacts of the European heatwave 2003

Ecological impacts of the European heatwave 2003

Relationships between the percentage of species loss and anomalies of moisture availability and growing-degree days

Thuiller W. et.al. PNAS 2005;102:8245-8250

Key Future Impacts and Vulnerabilities

• Biogeochemical cycles and biotic feedback

• Deserts: Vegetation response to rainfall variability in the Sahel Grasslands

and savannas

• Mediterranean ecosystems

• Forests and woodlands

• Tundra and Arctic/Antarctic ecosystems: Polar bears - a species in peril?

• Mountains

• Freshwater wetlands, lakes and rivers

• Oceans and shallow seas

• Cross-biome impacts: Crossing biomes: impacts of climate change on

migratory birds

• Global synthesis including impacts on biodiversity

Simulated Net Carbon Exchange Simulated Net Carbon Exchange of All Terrestrial Ecosystemof All Terrestrial Ecosystem

Vegetation Response to Rainfall Variability in the Vegetation Response to Rainfall Variability in the SahelSahel

Polar Bears – a species in perilPolar Bears – a species in peril

Coral reefs: Endangered by Climate Change?Coral reefs: Endangered by Climate Change?

Projected Appreciable Changes in Terrestrial Projected Appreciable Changes in Terrestrial Ecosystems Ecosystems

Compendium of Projected Risks due to Compendium of Projected Risks due to Critical Climate Change Impacts on Critical Climate Change Impacts on

EcosystemsEcosystems

Projected Risks due to Critical Climate Projected Risks due to Critical Climate Change Impacts on Ecosystems and Change Impacts on Ecosystems and

Population SystemsPopulation Systems

Projected Risks due to Critical Climate Projected Risks due to Critical Climate Change Impacts on Ecosystems and Change Impacts on Ecosystems and

Population SystemsPopulation Systems

Projected Risks due to Critical Climate Projected Risks due to Critical Climate Change Impacts on Ecosystems and Change Impacts on Ecosystems and

Population SystemsPopulation Systems

Food, Fibre, and Forest ProductsFood, Fibre, and Forest Products• In mid- to high-latitude regions, moderate warming benefits crop and pasture yields, but even slight warming decreases yields in seasonally dry and low-latitude regions.

• The marginal increase in the number of people at risk of hunger due to climate change must be viewed within the overall large reductions due to socio-economic development.

• Projected changes in the frequency and severity of extreme climate events have significant consequences for food and forestry production, and food insecurity, in addition to impacts of projected mean climate.

• Simulations suggest rising relative benefits of adaptation with low to moderate warming (medium confidence), although adaptation stresses water and environmental resources as warming increases.

• Smallholder and subsistence farmers, pastoralists and artisanal fisherfolk will suffer complex, localised impacts of climate change.

• Globally, commercial forestry productivity rises modestly with climate change in the short and medium term, with large regional variability around the global trend.

• Local extinctions of particular fish species are expected at edges of ranges.

• Food and forestry trade is projected to increase in response to climate change, with increased dependence on food imports for most developing countries.

• Experimental research on crop response to elevated CO2 confirms Third Assessment Report (TAR) findings. New Free-Air Carbon Dioxide Enrichment (FACE) results suggest lower responses for forests

Impact of Selected African DroughtsImpact of Selected African Droughts

European Heatwave Impact on the Agricultural SectorEuropean Heatwave Impact on the Agricultural Sector

European Heatwave Impact on the Agricultural SectorEuropean Heatwave Impact on the Agricultural Sector

Climate change and the fisheries of the lower Climate change and the fisheries of the lower MekongMekong

Assumptions about future trends in Assumptions about future trends in climate, food, forestry and fisheries climate, food, forestry and fisheries

Sensitivity of Cereal Yield to Climate ChangeSensitivity of Cereal Yield to Climate Change

Impacts on Grasslands of Incremental Impacts on Grasslands of Incremental Temperature ChangeTemperature Change

Examples of Simulated Climate Change Impacts on Examples of Simulated Climate Change Impacts on ForestryForestry

Impact of Coral Mortality on Reef Impact of Coral Mortality on Reef FisheriesFisheriesCoral reefs and their fisheries are subject to many stresses

in addition to climate change (see Chapter 4). So far,events such as the 1998 mass coral bleaching in theIndian Ocean have not provided evidence of negativeshort-term bio-economic impacts for coastal reef fisheries(Spalding and Jarvis, 2002; Grandcourt and Cesar, 2003).In the longer term, there may be serious consequencesfor fisheries production that result from loss of coralcommunities and reduced structural complexity, whichresult in reduced fish species richness, local extinctionsand loss of species within key functional groups of reeffish (Sano, 2004; Graham et al., 2006)

Observed Climate-related TrendsObserved Climate-related Trends

Impacts of Climate Change and Socio-Economic Develoment Impacts of Climate Change and Socio-Economic Develoment PathsPaths

:: the number of people at risk of hunger in developing the number of people at risk of hunger in developing countriescountries

Key Conclusions and Their Uncentainties, Key Conclusions and Their Uncentainties, Confidence Levels and Research GapsConfidence Levels and Research Gaps

• Projected changes in the frequency and severity of extreme climate events will have more serious consequences for food and forestry production, and food insecurity, than will changes in projectedmeans of temperature and precipitation.• Climate change increases the number of people at risk of hunger (high confidence). The impact of chosen socioeconomic pathways (SRES scenario) on the numbers of people at risk of hunger is significantly greater than the impact of climate change. Climate change will further shift the focus of food insecurity to sub-Saharan Africa.• While moderate warming benefits crop and pasture yields in mid- to high-latitude regions, even slight warming decreases yields in seasonally dry and low-latitude regions.• Experimental research on crop response to elevated CO2 confirms Third Assessment Report (TAR) findings). New Free-Air Carbon Dioxide Enrichment (FACE) results suggest lower responses for forests (medium confidence). Cropmodels include CO2 estimates close to the upper range of new research (high confidence), while forest models may overestimate CO2 effects.• Globally, commercial timber productivity risesmodestly with climate change in the short and medium term, with large regional variability around the global trend.• Local extinctions of particular fish species are expected at edges of ranges.• Food and forestry trade is projected to increase in response to climate change, with increased dependence of most developing countries on food imports.• Simulations suggest rising relative benefits of adaptation with low to moderate warming, although adaptation may stress water and environmental resources as warming increases.

Selected Conclusions for Food, Fibre, Selected Conclusions for Food, Fibre, Forestry, Forestry,

and Ffisheries, by Warming Incrementsand Ffisheries, by Warming Increments

Major impacts of climate change on crop and livestock yields, and forestry production

Selected Findings for Food, Fibre, Forestry, Selected Findings for Food, Fibre, Forestry, and Ffisheries, by Time Incrementsand Ffisheries, by Time Increments

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