www.merseyforest.org.uk green infrastructure for climate change adaptation - the role of spatial...
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www.merseyforest.org.uk
Green Infrastructure for Climate Change Adaptation
- the role of spatial planning
Dr Susannah [email protected]
www.merseyforest.org.uk
Climate change context
• Our climate is changing– Warming of the climate system is
unequivocal– Coherent changes in many aspects of the
climate system not just temperature
• Changes go beyond natural variability– Temperature change in last 50 years is very
likely (>90% chance) due to increase in anthropogenic greenhouse gas concentrations
IPCC (2007)
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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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Average Summer Maximum TemperatureScenarios for the North West
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Average Summer Precipitation Scenarios for the North West
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Average Winter Precipitation Scenarios for the North West
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Climate Change Management
Smit et al (1999)
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Mitigation – the role of GI
• Reducing greenhouse gas emissions and concentrations now impacts on the magnitude of future climate changes
• Limited but important role of GI– Carbon sequestration & storage– Direct fossil fuel substitution– Material substitution– High quality landscapes near to where
people live reducing, alternative routes to travel - reducing the need to travel by car
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Adaptation – the role of GI
• Changes over next 30-40 years already determined by historic emissions
• Crucial role of GI– Moderating temperature extremes,
especially in urban areas– Reducing volume and slowing rate of
rainwater runoff• Flood management• Soil erosion
– 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
Climate Change Impacts in the Built EnvironmentClimate Change Impacts in the Built Environment
• Built environment is distinctive– High building mass and low
greenspace cover leads to urban heat island
– Surface sealing increases rate and volume of rainfall runoff
• Climate change strengthens this distinctiveness
• Urban greenspace helps to moderate these impacts
• BUT climate change will also impact on functionality of urban greenspace
• Built environment is distinctive– High building mass and low
greenspace cover leads to urban heat island
– Surface sealing increases rate and volume of rainfall runoff
• Climate change strengthens this distinctiveness
• Urban greenspace helps to moderate these impacts
• BUT climate change will also impact on functionality of urban greenspace
Greater Manchester UMT MapGreater Manchester UMT Map
Evapotranspiring Surfaces Evapotranspiring Surfaces
‘Urban’ Tree Cover‘Urban’ Tree Cover
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’?
Summary of Research FindingsSummary of Research 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
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The role of spatial planning
• GI planning has an important role to play in climate change (especially adaptation)
• Functional importance of GI must be reflected in planning policy
GI functions for climate change…
Mitigation AdaptationBiofuels 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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All levels of spatial planning
• National – PPS– PPS1 supplement– Climate Change Adaptation by Design (TCPA,
2007)– Adapting to Climate Change – a checklist for
development (GLA, 2005)– Guidance for Local Authorities on Implementing
the Biodiversity Duty (Defra, 2007)• Regional – RSS• Local – LDF• Also important – Sub-Regional & non-
planning documents
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LDF
• GI Plan within LDF
• Climate change mitigation and adaptation functions a crucial part of this
• Developer contributions towards delivering GI Plan
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GI Plan• What is there and what functions is it providing?• Protect - Where it is critical environmental capital
– Urban centres, flood plains, private gardens on high infiltration soils
• Create - Where there is a need / functionality is lacking– High density residential and built up areas, low green
space cover with human vulnerability• Enhance - Where management changes could
improve functionality– Water storage capacity, wildlife corridors, SuDS
• Maintain - So that it continues to provide that function– Overall green space cover, times of water stress
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Example policies…• Sheffield City Council proposed green roof policy
– Required on all medium and larger developments (more than 15 dwellings / over 1000 m2 gross internal floor space)
– Encouraged on all other developments– Must be compatible with other design and conservation
considerations– Must cover at least 80% of the total roof area
• Hull City Council proposing development control & policies to reduce flooding impact & flood-proof new development– Remove permitted development rights to control loss of
private gardens– Lower development densities and higher green space &
public open space requirements – Flood proofing built into any new development
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Conclusion
• Our climate is changing• Need to mitigate and adapt
– Mitigation role of GI limited but important– Adaptation role of GI substantial
• Spatial planning has an important role to play in climate change adaptation– Planning policy must reflect the functional
importance of GI at all levels
• Need to know what we have and how it functions in order to protect, create, enhance, and maintain