Building resilient and sustainable cities

Stéphane 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 land-

use (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, Météo-France (V. Masson, G. Pigeon, A. Lemonsu, C. Marchadier)

City Brussels Budapest LisboaMexico

City

New

YorkParis Seoul Sydney

Percent of

land2.3 0.8 3.2 0.1 0.1 0.5 0.6 0.02

Percent of

population10 25.3 26.3 23.9 7.8 21.2 25 24.4

Percent of

GDP44.4 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.

The major economic role of cities

in economic development

Urban development and spatial inequality

Reducing energy consumption

Reducing urban risks

Limiting competition for land availability

Alleviating poverty

Accelerating economic

development

Actions need to be assessed

along several dimensions

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 long-

term 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

Rahmstorf (2007)

Source: IPCC (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

Learn Act

Learn ActLearn and revise

strategies

Traditional approach:

Robust decision-making:

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 lock-ins 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

Current risk level « optimal » risk level

No climate

change

With climate

change

Adaptation gap reduction

« Optimal»

adaptation

1 2

3 4

Constant-

level

adaptation

« Strict »

adaptation

Current situation

And it is not a two-stage process, but a

dynamic process!

Time

« Development »

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 priorités

Pertes liées aux inondations à Mumbai

Pertes dues à la crue centennale dans

différents scénarios d’adaptation 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?