Cities: IPCC Special
Report on Global Warmingof 1.5oC
A call to action
Debra Roberts
IPCC Co-Chair Working GroupIIFour system transitions“….require rapid and far-reaching transitions
in energy, land, urban and infrastructure(including transport and buildings), andindustrial systems.”
Rapid. Far-reaching. Unprecedented

A global scale opportunity“…. urban systems can harness the megatrends of urbanisation, digitalisation,
financialisation and growing sub-national
commitment to smart cities, green cities, resilientcities, sustainable cities and adaptive cities, forthe type of transformative change required by
1.5oC-consistent pathways”.

Urbanisation megatrend• World population is rising especially in mediumsized cities in low- and moderate-income
countries. Most affected people live in low andmiddle income countries.
• Urban population projected to increase by ~2billion by 2050
• 70 million additional urban residents per year until
mid-century• ~360 million people live in urban coastal areas• ~3 billion people will live in slums and informal
settlements by 2050

Jason Florio / Aurora Photos

Urbanisation megatrend
Transformational potential because of theconcentration:• economic activity• social networks• human resources• infrastructural investment• nimble local governments• connection to rural and naturalenvironments• Innovation
This transformation will involve both
ambitious mitigation and adaptation
Jason Florio / Aurora Photos

Cities at risk

5Cities – Increased risks• Climate change risks concentrate in cities• heat stress, flooding, vector-borne diseases,
air pollution, water scarcity, landslides, fire

• These risks could expose and amplify preexisting stresses• Poverty, exclusion, governance• Especially in African and Asian countries
where urbanisation rates are highest• Urbanisation leads to increased
consumption, environmental degradationand vulnerability
Jason Florio / Aurora Photos

Cities - Heat
• Urban heat island (UHI) effect increases
heat related health impacts in cities• Up to 30% increase of heat island effect fora doubling of CO2• Heat island effect amplified by greater
population and city size

• Twice as many megacities become heatstressed at 1.5°C than today• >350 million more people exposed to deadly
heat by 2050 (midrange population growth)• Even holding temperature to well below 2oC +UHI could result in a substantial increase indeadly heatwaves in cities
Jason Florio / Aurora Photos

Cities – Flooding and drought• Increased flooding and damage ofinfrastructure from extreme events• Compound flooding (from multiple drivers)in coastal cities• likely to increase with further development andsea level rise at 1.5°C and 2°C• 31-69 million people exposed to coastal
flooding at 1.5°C; 32-79 million at 2°C• Urban populations exposed to drought• 350.2 (±158.8) million at 1.5°C, 410.7 (±213.5)
million at 2°C
Jason Florio / Aurora Photos

Cities - Sea level rise
• 136+ megacities (> 1 million in 2005) at riskof sea level rise
• Salinization of groundwater• Localized subsidence causing greater
relative sea level rise

• Effect of storms amplified by sea level rise
• Dike height under no-mitigation scenario is2m higher in 2300 compared to scenarioswith mitigation, at 1.5°C or 2°C• ‘Coastal squeeze’: ocean and human activity
encroach on coastal ecosystems
Jason Florio / Aurora Photos

Cities – Poverty• Poverty and climate change• Climate change is a poverty-multiplier that makes
poor people poorer• >100 million people could be forced into extreme
poverty• Reduces incomes, widens inequality, reshapes
global economy• Most severe impacts projected for urban areasand some rural regions in sub-Saharan Africa andSoutheast Asia affected
Jason Florio / Aurora Photos

Responding throughadaptation

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Cities - Adaptation• 1.5°C pathways require action in all cities
and urban contexts• Cities are at the frontline of adaptation• Disaster risk reduction and management• Flood and drought early warning systems• Improving water storage and use• Regional differences in adaptation spending• Developing cities spend more on health andagriculture-related• Developed cities spend more on energy andwater
Gerhard Zwerger-Schoner / Aurora Photos

Cities - Adaptation• Adaptation activities lagging in emerging
economies• Major centres of population growth• Face complex interrelated investmentpressures in health, housing and education• In rapidly growing African and Asian cities,
poverty undermines adaptive capacity

Gerhard Zwerger-Schoner / Aurora Photos

Cities – Urban planning• Can address adaptation and mitigationneeds• Effective urban planning can reduce GHG
emissions from transport by 20 - 50%• Benefits of reduced air pollution, congestion,
fatalities and promote social cohesion• Consider implications of extreme events inurban design• Building codes and standards• Improved enforcement of codes• Maladaptation: Potential for industry interests
to undermine transformation of codes andprevent evolution of buildings or land use
Gerhard Zwerger-Schoner / Aurora Photos

Cities – Urban land use• Influences risk exposure, adaptive capacity• Investing in infrastructure and buildings
reduces risk
• Adaptation plans: reduce exposure to flood,heat stress, fire and sea-level rise

• Consider justice, equity, and broad
participation to avoid negative impacts on
poor
Gerhard Zwerger-Schoner / Aurora Photos

Cities – Sustainable Water• Sustainable water resource
management through waste-water
recycling and storm water diversion• Urban design to mediate run off,encourage groundwater recharge andenhance water quality.
• Water-energy-food nexus can support
policy coherence

Gerhard Zwerger-Schoner / Aurora Photos

Cities – Green Urban Infrastructure andEcosystem Services
Green infrastructure

Adaptation benefits

Mitigation benefits

Urban trees planting,urban parks

Reduced heat island effect,
psychological benefits

Less cement, reduced airconditioning

Permeable surfaces

Water rechargeLess cement in city, some biosequestration, less water pumping

Forest retention, urban Flood mediation, healthy
agricultural landlifestyles

Air pollution reduction

Wetland restoration,
riparian buffer zones

Reduced urban flooding, Low Some bio-sequestration, Less
skilled local work, Sense ofenergy spent on water treatment
place

Biodiverse urban
habitat

Psychological benefits, inner- Carbon sequestrationcity recreation

Governance for action

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Cities - Governance• Urban governance is critical to ensuring that thenecessary urban transitions deliver economic
growth and equity• Local governments can be powerful agents ofclimate action• Urban governance is enhanced when it
involves:•••multiple actors
supportive national governments
sub-national climate networks• Climate resilient development pathways
Ashley Cooper/ Aurora Photos

AR6 Chapter 6 – Cities, settlements
and key infrastructure• Changes in the international policy architecture
for settlements since AR5 (including SDGs)• Interactions of climate risks with urban and ruralchange processes including food-energy-waterhealth nexus (e.g., air quality)• Risk-reducing infrastructure and services(including ecological and social), their deficits,
and implications for vulnerability, exposure andadaptation, particularly in the context of extreme
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AR6 Chapter 6 – Cities, …
• Detection and attribution of observed impacts
and responses and projected risks from climatechange under alternative scenarios for cities andsettlements, and related infrastructure• Adaptation options, adaptive capacity,responses and outcomes, including equity
considerations, and links to mitigation• Institutional, financial, and governancestructures that enhance resilience of and enable
adaptation in settlements, cities and key
infrastructure• Lessons from case studies
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Thank you

Q&A