Building resilient and sustainable cities
StĂŠphane Hallegatte World Bank and Meteo-France
Urban planning faces many policy goals Urban forms matter for greenhouse gas emissions and energy consumption
Urban forms matter for climate-change vulnerability (urban heat island, flood vulnerability,…) Urban development competes with other category of landuse (e.g., agriculture, natural areas) Urban development is crucial for economic development, and is a factor of social and spatial inequalities. Building sustainable cities create unprecedented decision-making issues
Urban forms and energy consumption
Lower energy consumption in Barcelona because of: 1 - Shorter travel distance; 2 – Easier use of public transport:
Source: Alain Bertaud
Urban forms and vulnerability
Temperatures are higher in cities than in rural areas, especially at night. Example of the 2003 heat wave in Paris.
Source: CNRM, MĂŠtĂŠo-France (V. Masson, G. Pigeon, A. Lemonsu, C. Marchadier)
The major economic role of cities in economic development City
Brussels Budapest Lisboa
Mexico City
New York
Paris
Seoul
Sydney
Percent of land
2.3
0.8
3.2
0.1
0.1
0.5
0.6
0.02
Percent of population
10
25.3
26.3
23.9
7.8
21.2
25
24.4
Percent of GDP
44.4
45.6
38
26.7
8.5
27.9
48.6
23.5
Sources: Land: Klein Goldewijk and Van Drecht, 2006; population: UN, 2006; and GDP: OECD, 2006.
Urban development and spatial inequality
Actions need to be assessed along several dimensions Reducing energy consumption
Accelerating economic development
Alleviating poverty
Reducing urban risks
Limiting competition for land availability
It is crucial to look for synergies between these different policy goals. It is the objective of the Green Growth Strategies, on which the WB is preparing a report (available March 2012).
A complement to economic analyses
Adaptation & incertitude
Resilient urban planning means anticipation Adaptation will require technical know-how and substantial funding. Adaptation requires also anticipation, especially in sectors with longterm investments: – Water management infrastructure (lifetime: up to 200 years); – Energy production and distribution infrastructure (up to 80 years); – Transportation infrastructure (50 to 200 years) ; – Natural disaster protections (50 to 200 years); – Urbanism, housing and architecture (25 years to centuries). These infrastructures represent more than 100% of GDP. In most developing countries, cities and infrastructures are currently being built and it is urgent to take climate change into account.
e.g., the Bouregreg Valley Project.
One possible future climate‌ Climate analogues in 2070, Hadley Centre Model, SRES A2
A new building in Paris needs to be adapted to the current climate of Paris, and to the future climate of Paris, i.e. the current climate in Cordoba.
… and another Climate analogues in 2070, Météo-France Model, SRES A2
A new building in Paris needs to be able to cope with any of the possible future climates…
IPCC, 2007
Uncertainty in sea level rise Source: IPCC (2007)
Rahmstorf (2007)
Public action for sustainable cities
Five domains of public action Creating and distributing information – Information production and diffusion to the population – Early detection of climate change signals Coordinating private-actor actions – Need for cooperation between private and public actors – Role of norms and regulations (e.g., building norms, insurance) – Regional and urban development plans Avoiding negative consequences of adaptation actions – Change in water use (e.g., irrigation) – Air conditioning and energy consumption Preserving equity and alleviating poverty – A fraction of the population cannot afford adaptation investment and need support Direct investment actions – Transport, water management, public buildings, etc.
Looking for robustness Traditional approach:
Learn
Act
Robust decision-making:
Learn
Act
Learn and revise strategies
It is critical to select strategies that can be revised over time, as a function of new information and knowledge.
Looking for robustness Selecting no-regret strategies that bring benefits even in absence of climate change, and for most climate scenarios: – Most Disaster Risk Reduction Actions; – Improvement in building norms; Favoring reversible strategies over irreversible ones (avoid lock-ins): – More restrictive land-use plans; Investing in low-cost “safety margins”: – Drainage infrastructures in Copenhagen. Reducing investment lifetimes: – Housing building quality and lifetime in flood-prone areas (“Building strong”?) Favoring financial and institutional (“soft”) adaptation over “hard adaptation”: – Early warning, evacuation and insurance vs. sea walls and dikes.
Conclusions When uncertainty is large, the main objective is to avoid lockins in vulnerable situations, and to keep the possibility of adjust in case pessimistic scenarios reveal correct.
There are many suboptimal situations that can be corrected, creating “no-regret” opportunities. Uncertainty cannot justify inaction.
But uncertainty requires using different decision-making methods. It is dangerous to implement an « optimal » strategy, designed for only one scenario. Strategies should be designed to increase robustness and resilience, and account for many scenarios.
Several definitions for adaptation « Development »
Current risk level
No climate change
« optimal » risk level
Adaptation gap reduction 1 Current situation
2
Constantlevel adaptation
Time
With climate change
« Strict » adaptation
3
« Optimal» adaptation
And it is not a two-stage process, but a dynamic process!
4
Plan National d’Adaptation en France Première phase (2008-2009): Sélection de 2 scénarios climatiques et économiques Approche participative pour identifier les impacts du changement climatique – Gouvernement, autorités locales, employeurs, syndicats de travailleurs, ONG Seconde phase (2010): Approche participative pour identifier des mesures d’adaptation Evaluation participative, à l’aide de méthodes simples, avec 6 métriques (urgence, coût et bénéfice monétaire, santé, biodiversité, qualité de vie, impact redistributif), et des critères de robustesse. Evaluation détaillé des mesures: – Cohérence avec les autres objectifs politiques – Robustesse à l’incertitude climatique & économique – Si possible et nécessaire, analyse économique et financière détaillée Définition d’indicateurs de succès Suivi: Revue et révision tous les 5 (?) ans
Un moyen de fixer des prioritĂŠs
Pertes liées aux inondations à Mumbai
L’adaptation peut réduire les pertes en deçà de leur niveau actuel Ces actions sont « sans regret » Pourquoi ces actions n’ont-elles pas été mises en place? – Contraintes financières? – Fragmentation institutionnelle? – Manque de volonté politique et faible poids politique des populations touchées?
Pertes dues à la crue centennale dans différents scénarios d’adaptation