Download Community Forests and the Climate Change Agenda

Green Infrastructure for
Climate Change Adaptation
- the role of spatial planning
Dr Susannah Gill
[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)
www.merseyforest.org.uk
UK Climate Changes
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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 Temperature
Scenarios 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
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Smit et al (1999)
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
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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
www.merseyforest.org.uk
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
www.merseyforest.org.uk
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 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
Greater Manchester UMT Map
Evapotranspiring Surfaces
UMT
‘Urban’ Tree Cover
remnant countryside
disused & derelict land
distribution & storage
offices
manufacturing
town centre
retail
hospitals
schools
low density residential
medium density residential
high density residential
cemeteries & crematoria
refuse disposal
water storage & treatment
energy production & distribution
river, canal
rail
airports
major roads
allotments
informal open space
formal open space
formal recreation
mineral workings & quarries
woodland
0
2
4
6
8
10 12 14 16 18 20 22 24 26 28 30
Percentage of all 'urban' tree cover
Maximum Surface Temperatures
For a day occurring on
average twice per summer
Residential ± 10% green cover
High density residential
Max surface temp (°C)
40
35
current form
30
-10% green
25
+10% green
20
15
1970s
2020s
Low
2020s
High
2050s
Low
2050s
High
Time period and scenario
2080s
Low
2080s
High
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
(Manchester Evening News, 2006)
Occurrence of Drought for Grass
Months/year when grass water
stressed
Adaptation 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 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 Capacity
A case for
‘Conservation
Areas’?
Summary 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
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
www.merseyforest.org.uk
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
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 & nonplanning documents
www.merseyforest.org.uk
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
www.merseyforest.org.uk
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
www.merseyforest.org.uk
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
www.merseyforest.org.uk