Person:
Hallegatte, Stephane

Climate Change Group

Fields of Specialization

Green growth, Climate change, Urban development

ORCID

0000-0002-1781-4268

Departments

Climate Change Group

Last updated January 31, 2023

Biography

Stéphane Hallegatte is a lead economist with the Global Facility for Disaster Reduction and Recovery (GFDRR) at the World Bank. He joined the World Bank in 2012 after 10 years of academic research in environmental economics and climate science for Météo-France, the Centre International de Recherche sur l’Environnement et le Développement, and Stanford University. His research interests include the economics of natural disasters and risk management, climate change adaptation, urban policy and economics, climate change mitigation, and green growth. Mr. Hallegatte was a lead author of the 5th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). He is the author of dozens of articles published in international journals in multiple disciplines and of several books, including Green Economy and the Crisis: 30 Proposals for a More Sustainable France, Risk Management: Lessons from the Storm Xynthia, and Natural Disasters and Climate Change: An Economic Perspective. He also co-led the World Bank reports Inclusive Green Growth: The Pathway to Sustainable Development, published in 2012 and Decarbonizing Development in 2015, and was member of the core writing team of the 2014 World Development Report Risk and Opportunity: Managing Risks for Development. Most recently, he led the World Bank report Shock Waves: Managing the Impacts of Climate Change on Poverty, published in 2015 just before the Paris conference on climate change. He was the team leader for the World Bank Group Climate Change Action Plan, a large internal coordination exercise to determine and explain how the Group will support countries in their implementation of the Paris Agreement. Mr. Hallegatte holds engineering degrees from the Ecole Polytechnique (Paris) and the Ecole Nationale de la Météorologie (Toulouse), a master's degree in meteorology and climatology from the Université Paul Sabatier (Toulouse) and a Ph.D in economics from the Ecole des Hautes Etudes en Sciences Sociales (Paris).

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Publication Search Results

Now showing 1 - 10 of 71

Marginal Abatement Cost Curves and the Optimal Timing of Mitigation Measures

(Elsevier, 2013-12-04) Vogt-Schilb, Adrien ; Hallegatte, Stéphane

Decision makers facing abatement targets need to decide which abatement measures to implement, and in which order. Measure-explicit marginal abatement cost curves depict the cost and abating potential of available mitigation options. Using a simple intertemporal optimization model, we demonstrate why this information is not sufficient to design emission reduction strategies. Because the measures required to achieve ambitious emission reductions cannot be implemented overnight, the optimal strategy to reach a short-term target depends on longer-term targets. For instance, the best strategy to achieve European's −20% by 2020 target may be to implement some expensive, high-potential, and long-to-implement options required to meet the −75% by 2050 target. Using just the cheapest abatement options to reach the 2020 target can create a carbon-intensive lock-in and make the 2050 target too expensive to reach. Designing mitigation policies requires information on the speed at which various measures to curb greenhouse gas emissions can be implemented, in addition to the information on the costs and potential of such measures provided by marginal abatement cost curves.
An Exploration of the Link between Development, Economic Growth, and Natural Risk

(World Bank, Washington, DC, 2013-05-05) Hallegatte, Stéphane

This paper investigates the link between development, economic growth, and the economic losses from natural disasters in a normative analytical framework with an illustration on hurricane flood risks in New Orleans. It concludes that under broad conditions it is optimal for (1) the probability of disaster occurrence to decrease with income; (2) the capital at risk—and thus the economic losses in case of disaster — to increase faster than economic growth; and (3) the average annual losses to grow faster than income at low levels of development and slower than income at high levels of development. Increasing risk-taking reinforces economic growth; improving protections transfers risks from frequent low-intensity events to rare high-impact events.
Green Industrial Policies : When and How

(World Bank, Washington, DC, 2013-10) Hallegatte, Stephane ; Fay, Marianne ; Vogt-Schilb, Adrien

Green industrial policies can be defined as industrial policies with an environmental goal -- or more precisely, as sector-targeted policies that affect the economic production structure with the aim of generating environmental benefits. This paper provides a framework to assess their desirability depending on the effectiveness and political acceptability of price instruments. The main messages are the following. (i) Greening growth processes to the extent and with the speed needed cannot be done without industrial policies, even if prices can be adjusted to reflect environmental objectives. (ii) "Sunrise" green industrial policies are needed because they support the development of critical new technologies and sectors, bring down costs, and allow for reduced emissions in the short term even in the absence of carbon pricing. (iii) "Sunset" green industrial policies and trade policies may be needed in conjunction with safety nets to make carbon pricing politically or socially acceptable. They can help mitigate the impact of a carbon price on competitiveness and unemployment and smooth the transition by helping industries adjust to the new conditions. (iv) Green or not, industrial policy requires carefully navigating the twin dangers of market and governance failure. The viability of supported technologies and sectors is difficult to assess through a market-test given their dependence on continued environmental policies or pricing -- such as a carbon price. Particular attention must be paid to avoid potential unintended negative effects, such as rebound effects (especially if prices are inappropriate), misallocation of capital, or capture and rent-seeking behaviors.
How Capital-Based Instruments Facilitate the Transition Toward a Low-Carbon Economy : A Tradeoff between Optimality and Acceptability

(World Bank, Washington, DC, 2013-09) Rozenberg, Julie ; Vogt-Schilb, Adrien ; Hallegatte, Stephane

This paper compares the temporal profile of efforts to curb greenhouse gas emissions induced by two mitigation strategies: a regulation of all emissions with a carbon price and a regulation of emissions embedded in new capital only, using capital-based instruments such as investment regulation, differentiation of capital costs, or a carbon tax with temporary subsidies on brown capital. A Ramsey model is built with two types of capital: brown capital that produces a negative externality and green capital that does not. Abatement is obtained through structural change (green capital accumulation) and possibly through under-utilization of brown capital. Capital-based instruments and the carbon price lead to the same long-term balanced growth path, but they differ during the transition phase. The carbon price maximizes social welfare but may cause temporary under-utilization of brown capital, hurting the owners of brown capital and the workers who depend on it. Capital-based instruments cause larger intertemporal welfare loss, but they maintain the full utilization of brown capital, smooth efforts over time, and cause lower immediate utility loss. Green industrial policies including such capital-based instruments may thus be used to increase the political acceptability of a carbon price. More generally, the carbon price informs on the policy effect on intertemporal welfare but is not a good indicator to estimate the impact of the policy on instantaneous output, consumption, and utility.
Long-Term Mitigation Strategies and Marginal Abatement Cost Curves : A Case Study on Brazil

(World Bank, Washington, DC, 2014-03) Vogt-Schilb, Adrien ; Hallegatte, Stephane ; de Gouvello, Christophe

Decision makers facing abatement targets need to decide which abatement measures to implement, and in which order. This paper investigates the ability of marginal abatement cost (MAC) curves to inform this decision, reanalysing a MAC curve developed by the World Bank on Brazil. Misinterpreting MAC curves and focusing on short-term targets (e.g., for 2020) would lead to under-invest in expensive, long-to-implement and large-potential options, such as clean transportation infrastructure. Meeting short-term targets with marginal energy-efficiency improvements would lead to carbon-intensive lock-ins that make longer-term targets (e.g., for 2030 and beyond) impossible or too expensive to reach. Improvements to existing MAC curves are proposed, based on (1) enhanced data collection and reporting; (2) a simple optimization tool that accounts for constraints on implementation speeds; and (3) new graphical representations of MAC curves. Designing climate mitigation policies can be done through a pragmatic combination of two approaches. The synergy approach is based on MAC curves to identify the cheapest mitigation options and maximize co-benefits. The urgency approach considers the long-term objective (e.g., halving emissions by 2050) and works backward to identify actions that need to be implemented early, such as public support to clean infrastructure and zero-carbon technologies.
Economic Resilience : Definition and Measurement

(World Bank, Washington, DC, 2014-05) Hallegatte, Stephane

The welfare impact of a disaster does not only depend on the physical characteristics of the event or its direct impacts in terms of lost lives and assets. Welfare impacts also depend on the ability of the economy to cope, recover, and reconstruct and therefore to minimize aggregate consumption losses. This ability can be referred to as the macroeconomic resilience to natural disasters. Macroeconomic resilience has two components: instantaneous resilience, which is the ability to limit the magnitude of immediate production losses for a given amount of asset losses, and dynamic resilience, which is the ability to reconstruct and recover. Welfare impacts also depend on micro-economic resilience, which depends on the distribution of losses; on households' vulnerability, such as their pre-disaster income and ability to smooth shocks over time with savings, borrowing, and insurance, and on the social protection system, or the mechanisms for sharing risks across the population. The (economic) welfare disaster risk in a country can be reduced by reducing the exposure or vulnerability of people and assets (reducing asset losses), increasing macroeconomic resilience (reducing aggregate consumption losses for a given level of asset losses), or increasing microeconomic resilience (reducing welfare losses for a given level of aggregate consumption losses). The paper proposes rules of thumb to estimate macroeconomic and microeconomic resilience based on the relevant parameters in the economy. It also provides a toolbox of policies to increase macro- or micro-economic resilience and a list of indicators that can be used to build a resilience indicator.
Transition to Clean Capital, Irreversible Investment and Stranded Assets

(World Bank, Washington, DC, 2014-05) Rozenberg, Julie ; Vogt-Schilb, Adrien ; Hallegatte, Stephane

This paper uses a Ramsey model with two types of capital to analyze the optimal transition to clean capital when polluting investment is irreversible. The cost of climate mitigation decomposes as a technical cost of using clean instead of polluting capital and a transition cost from the irreversibility of pre-existing polluting capital. With a carbon price, the transition cost can be limited by underutilizing polluting capital, at the expense of a loss in the value of polluting assets (stranded assets) and a drop in income. In contrast, policy instruments that focus on redirecting investments -- such as feebates or environmental standards -- prevent underutilization of existing capital, avoid stranded assets, and reduce short-term losses; but they reduce emissions more slowly and increase the intertemporal cost of the transition. The paper investigates inter- and intra-generational distributional impacts and the political acceptability of climate change mitigation policy instruments.
Measuring Natural Risks in the Philippines: Socioeconomic Resilience and Wellbeing Losses

(World Bank, Washington, DC, 2019-01) Walsh, Brian ; Hallegatte, Stephane

Traditional risk assessments use asset losses as the main metric to measure the severity of a disaster. This paper proposes an expanded risk assessment based on a framework that adds socioeconomic resilience and uses wellbeing losses as its main measure of disaster severity. Using a new, agent-based model that represents explicitly the recovery and reconstruction process at the household level, this risk assessment provides new insights into disaster risks in the Philippines. First, there is a close link between natural disasters and poverty. On average, the estimates suggest that almost half a million Filipinos per year face transient consumption poverty due to natural disasters. Nationally, the bottom income quintile suffers only 9 percent of the total asset losses, but 31 percent of the total wellbeing losses. The average annual wellbeing losses due to disasters in the Philippines is estimated at US$3.9 billion per year, more than double the asset losses of US$1.4 billion. Second, the regions identified as priorities for risk-management interventions differ depending on which risk metric is used. Cost-benefit analyses based on asset losses direct risk reduction investments toward the richest regions and areas. A focus on poverty or wellbeing rebalances the analysis and generates a different set of regional priorities. Finally, measuring disaster impacts through poverty and wellbeing impacts allows the quantification of the benefits from interventions like rapid post-disaster support and adaptive social protection. Although these measures do not reduce asset losses, they efficiently reduce their consequences for wellbeing by making the population more resilient.
Investment Decision Making Under Deep Uncertainty : Application to Climate Change

(World Bank, Washington, DC, 2012-09) Hallegatte, Stéphane ; Shah, Ankur ; Lempert, Robert ; Brown, Casey ; Gill, Stuart

While agreeing on the choice of an optimal investment decision is already difficult for any diverse group of actors, priorities, and world views, the presence of deep uncertainties further challenges the decision-making framework by questioning the robustness of all purportedly optimal solutions. This paper summarizes the additional uncertainty that is created by climate change, and reviews the tools that are available to project climate change (including downscaling techniques) and to assess and quantify the corresponding uncertainty. Assuming that climate change and other deep uncertainties cannot be eliminated over the short term (and probably even over the longer term), it then summarizes existing decision-making methodologies that are able to deal with climate-related uncertainty, namely cost-benefit analysis under uncertainty, cost-benefit analysis with real options, robust decision making, and climate informed decision analysis. It also provides examples of applications of these methodologies, highlighting their pros and cons and their domain of applicability. The paper concludes that it is impossible to define the "best" solution or to prescribe any particular methodology in general. Instead, a menu of methodologies is required, together with some indications on which strategies are most appropriate in which contexts. This analysis is based on a set of interviews with decision-makers, in particular World Bank project leaders, and on a literature review on decision-making under uncertainty. It aims at helping decision-makers identify which method is more appropriate in a given context, as a function of the project's lifetime, cost, and vulnerability.
How Inertia and Limited Potentials Affect the Timing of Sectoral Abatements in Optimal Climate Policy

(World Bank, Washington, DC, 2012-08) Vogt-Schilb, Adrien ; Meunier, Guy ; Hallegatte, Stephane

This paper investigates the optimal timing of greenhouse gas abatement efforts in a multi-sectoral model with economic inertia, each sector having a limited abatement potential. It defines economic inertia as the conjunction of technical inertia -- a social planner chooses investment on persistent abating activities, as opposed to choosing abatement at each time period independently -- and increasing marginal investment costs in abating activities. It shows that in the presence of economic inertia, optimal abatement efforts (in dollars per ton) are bell-shaped and trigger a transition toward a low-carbon economy. The authors prove that optimal marginal abatement costs should differ across sectors: they depend on the global carbon price, but also on sector-specific shadow costs of the sectoral abatement potential. The paper discusses the impact of the convexity of abatement investment costs: more rigid sectors are represented with more convex cost functions and should invest more in early abatement. The conclusion is that overlapping mitigation policies should not be discarded based on the argument that they set different marginal costs (`"different carbon prices"') in different sectors.