green infrastructure and climate change

www.merseyforest.org.uk

Green Infrastructure and Climate Change

Dr Susannah Gill

The Mersey Forest

susannahgill@merseyforest.org.uk

www.merseyforest.org.uk

Overview

• Green infrastructure• Climate change• Green infrastructure for adaptation in

urban areas• Policy relevance in the UK• North West Climate Change Action Plan• Conclusions

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Green Infrastructure

• Life support system – the network of natural environmental components and green and blue spaces that lie within and between our cities, towns and villages and provide multiple social, economic and environmental benefits

• http://www.greeninfrastructurenw.org.uk

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Our Climate is Changing

(source: IPCC, 2007)

• Warming of the climate system is unequivocal

• Coherent changes in many aspects of the climate system not just temperature

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Changes go beyond natural variability

Temperature change in last 50 years is very likely (>90% chance) due to increase in anthropogenic greenhouse gas concentrations

(source: IPCC, 2007)

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Global climate change projections

(source: IPCC, 2007)

(rel

ativ

e to

198

0-99

)

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What does this mean for the UK?

• UKCIP02– 4 emissions scenarios– 3 time slices– 50 km outputs (some 5 km)

• UKCIP08– Probabilistic scenarios– 25 km output– Due October 2008

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UK Climate Changes• Average temp increases• High temp extremes increase in frequency• Low temp extremes decrease in frequency• Sea-surface temp warms• Thermal growing season lengthens• Winter precipitation increases• Winter precipitation intensity increases• Greater contrast between summer & winter• Snowfall decreases• Summer soil moisture decreases• Sea-level rises

UKCIP02 High Confidence Levels

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Greater Manchester Average Maximum Summer Temperature

Data from the UK Met Office and UKCIP02

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Greater Manchester Summer Precipitation

Data from the UK Met Office and UKCIP02

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Greater Manchester Winter Precipitation

Data from the UK Met Office and UKCIP02

Baseline (1961-90)

2050s Low emissions

2050s High emissions

2080s High emissions

Manchester(Mean Annual Temp)

Slide courtesy of Mark Broadmeadow

Baseline (1961-90)

2050s Low emissions

2050s High emissions

2080s High emissions

Manchester(monthly mean temp, diurnal temp range & precipitation)

Slide courtesy of Mark Broadmeadow

Matt Cardy/Getty Images

Source: The Guardian website

Daniel Berehulak/Getty Images

Kate Gillon/Getty Images

Source: Stott et al, 2004

June-Aug temp anomalies (relative to 1961-1990 mean)

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Climate Change Management

Smit et al (1999)

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Mitigation Role of GI

• Carbon sequestration & storage

• Direct fossil fuel substitution

• Material substitution

• Local food production

• Reducing need to travel

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Adaptation Role of GI

• Moderating temperature extremes

• Decreasing rate and volume of rainwater runoff

• Providing wildlife corridors

• Providing recreation spaces e.g. high capacity, less sensitive landscapes

Key Stakeholders

Town & Country Planning Association (Chair)

Association of British Insurers

Environment Agency

North West Climate Group

Office of the Deputy Prime Minister

Royal Town Planning Institute

South East Climate Group

http://www.k4cc.org/Members/Claire/BKCC-Results-Publication.pdf

ASCCUE MethodologyASCCUE Methodology

• Two case study areas– Greater Manchester – Lewes, Sussex

• Three exposure units– Integrity of the built

environment– Human comfort– Urban greenspace

• Two case study areas– Greater Manchester – Lewes, Sussex

• Three exposure units– Integrity of the built

environment– Human comfort– Urban greenspace

Urban GreenspaceUrban Greenspace

• Urbanisation alters – Micro-climate – increased temperatures – Hydrology – increased rate & volume of surface

runoff

• Climate change alters temperature & rainfall patterns

• Urban greenspace can moderate ‘urban heat island’ effect and reduce rate & volume of runoff

• Therefore urban greenspace has potential to adapt cities to climate change

• Urbanisation alters – Micro-climate – increased temperatures – Hydrology – increased rate & volume of surface

runoff

• Climate change alters temperature & rainfall patterns

• Urban greenspace can moderate ‘urban heat island’ effect and reduce rate & volume of runoff

• Therefore urban greenspace has potential to adapt cities to climate change

Urban Morphology TypesUrban Morphology Types

Urban CharacterisationUrban Characterisation

Greater Manchester Urban Morphology TypesGreater Manchester Urban Morphology Types

UMT Surface CoverUMT Surface Cover

‘Evapotranspiring’ Surfaces ‘Evapotranspiring’ Surfaces

‘Urban’ Tree Cover‘Urban’ Tree Cover

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

woodlandmineral workings & quarries

formal recreationformal open space

informal open spaceallotments

major roadsairports

railriver, canal

energy production & distributionwater storage & treatment

refuse disposalcemeteries & crematoria

high density residentialmedium density residential

low density residentialschools

hospitalsretail

town centremanufacturing

officesdistribution & storage

disused & derelict landremnant countryside

UM

T

Percentage of all 'urban' tree cover

Surface Cover and Residential DensitySurface Cover and Residential Density

Modelling environmental functionsModelling environmental functions

• Use surface cover data as one input into surface temperature and runoff models

• Series of model runs– Current urban form

• Baseline and future climate

– ‘Development scenarios’• Baseline and future climate

• Use surface cover data as one input into surface temperature and runoff models

• Series of model runs– Current urban form

• Baseline and future climate

– ‘Development scenarios’• Baseline and future climate

Maximum Surface TemperaturesMaximum Surface Temperatures

For a day occurring on average twice per summer

Residential ± 10% green coverResidential ± 10% green cover

High density residential

15

20

25

30

35

40

1970s 2020sLow

2020sHigh

2050sLow

2050sHigh

2080sLow

2080sHigh

Time period and scenario

Max

su

rfac

e te

mp

(°C

)

current form

-10% green

+10% green

High density residential

15

20

25

30

35

40

1970s 2020sLow

2020sHigh

2050sLow

2050sHigh

2080sLow

2080sHigh

Time period and scenario

Max

su

rfac

e te

mp

(°C

)

current form

-10% green

+10% green

If grass does not evapotranspire…If grass does not evapotranspire…

• Maximum surface temperatures increase by– 4.7-5.7°C in high

density residential areas

– 13.8-15.6°C in schools

• Maximum surface temperatures increase by– 4.7-5.7°C in high

density residential areas

– 13.8-15.6°C in schools

(Manchester Evening News, 2006)

Occurrence of Drought for GrassOccurrence of Drought for Grass

Months/year when grass water stressed

Adaptation in the Public RealmAdaptation in the Public Realm

Surface temperature in tree shade here was 13°C cooler than in sun – large mature tree canopies provide more shade

Surface RunoffSurface Runoff

56% more rain results in 82% more runoff

For a precipitation event occurring on average one day per winter, with normal antecedent moisture conditions

Infiltration CapacityInfiltration Capacity

A case for ‘Conservation

Areas’?

Climatic adaptation via the green infrastructureClimatic adaptation via the green infrastructure

Corridor

Patch

Matrix

Corridor Patch Matrix

Flood storage

• • • • • •

Infiltration capacity

• • • • • •

Evaporative cooling

• • • • • •

Shading • • • • • •

Functional importance of urban greenspace needs to be reflected in plans, policies, strategies

Summary of FindingsSummary of Findings

• Greenspace moderates temperatures through evaporative cooling & shading– Mature trees critical for shading

• Most effective in regulating surface runoff on high infiltration soils

• Increase rainwater storage

• Opportunity to use for irrigation in times of drought

• Greenspace moderates temperatures through evaporative cooling & shading– Mature trees critical for shading

• Most effective in regulating surface runoff on high infiltration soils

• Increase rainwater storage

• Opportunity to use for irrigation in times of drought

Policy ImplicationsPolicy Implications

• Work across administrative boundaries & disciplines

• Protect critical environmental capital• No net loss of green cover• Creative greening• Take opportunities in new development /

restructuring• Ensure water supply

• Work across administrative boundaries & disciplines

• Protect critical environmental capital• No net loss of green cover• Creative greening• Take opportunities in new development /

restructuring• Ensure water supply

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Increasing Policy Relevance

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NW Climate Change Action Plan

• “Undertake scoping studies to assess future regional risks, opportunities and priorities for the potential for green infrastructure, including regional parks, to adapt and mitigate for climate change impacts and commence implementation of findings”

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GI functions for climate change

Mitigation Adaptation

Biofuels production

Timber production

Food production

Carbon storage

Recreation

Green travel routes

Shading from sun

Evaporative cooling

Shading from sun

Evaporative cooling

Water storage

Water interception

Water infiltration

Soil stabilisation

Storm protection

Habitat for wildlife

Corridor for wildlife

Recreation

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Conclusion

• Climate change mitigation role limited but important

• Climate change adaptation role substantial

• GI is a good adaptation strategy as it has other functions and benefits

• To maximise this need strategic planning at all levels, with functionality in mind

• Protect, create, enhance, and maintain