Upload
cmi-marseille
View
226
Download
1
Tags:
Embed Size (px)
DESCRIPTION
http://cmimarseille.org/cmiarchive/_src/UD2_wk2/UD2_wk2_Hallegatte.pdf
Citation preview
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?