Ud2 wk2 hallegatte

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  • Building resilient and sustainable cities

    Stphane 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, Mto-France (V. Masson, G. Pigeon, A. Lemonsu, C. Marchadier)

  • City Brussels Budapest LisboaMexico



    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


    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, Mto-France Model, SRES A2

    A new building in Paris needs to be able to cope with any of the possible future


  • 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


    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


    With climate


    Adaptation gap reduction



    1 2

    3 4






    Current situation

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

    dynamic process!



  • Plan National dAdaptation en France

    Premire phase (2008-2009):

    Slection de 2 scnarios climatiques et conomiques

    Approche participative pour identifier les impacts du changement climatique

    Gouvernement, autorits locales, employeurs, syndicats de travailleurs, ONG

    Seconde phase (2010):

    Approche participative pour identifier des mesures dadaptation

    Evaluation participative, laide de mthodes simples, avec 6 mtriques (urgence, cot et bnfice montaire, sant, biodiversit, qualit de vie, impact redistributif), et des critres de robustesse.

    Evaluation dtaill des mesures:

    Cohrence avec les autres objectifs politiques

    Robustesse lincertitude climatique & conomique

    Si possible et ncessaire, analyse conomique et financire dtaille

    Dfinition dindicateurs de succs


    Revue et rvision tous les 5 (?) ans

  • Un moyen de fixer des priorits

  • Pertes lies aux inondations Mumbai

    Pertes dues la crue centennale dans

    diffrents scnarios dadaptation Ladaptation peut rduire les

    pertes en de de leur niveau


    Ces actions sont sans regret

    Pourquoi ces actions nont-elles pas t mises en place?

    Contraintes financires?

    Fragmentation institutionnelle?

    Manque de volont politique et faible poids politique des

    populations touches?