Hallegatte, Stéphane

Person:
Hallegatte, Stéphane

Climate Change Group, The World Bank

Author Name Variants

Hallegatte, Stephane, Hallegatte, Stéphane

Fields of Specialization

Green growth, Climate change, Urban development

Last updated: June 26, 2025

Biography

Stéphane Hallegatte is Chief Climate Economist 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 resilient low-emission development, the monitoring and measurement of climate policies on jobs, incomes, poverty, and quality of life; the inclusion of climate change and natural disasters in macroeconomic models and poverty assessments; and exploring the political economy of policies and their robustness to uncertainty. 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 reports Shock Waves: Managing the Impacts of Climate Change on Poverty , Unbreakable: Building the Resilience of the Poor in the Face of Natural Disasters , and Lifelines: the Resilient Infrastructure Opportunity. 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 80

The Macroeconomic Implications of Climate Change Impacts and Adaptation Options: A Modeling Approach
(Washington, DC: World Bank, 2025-05-29) Abalo, Kodzovi; Boehlert, Brent; Bui, Thanh; Burns, Andrew; Castillo, Diego; Chewpreecha, Unnada; Haider, Alexander; Hallegatte, Stephane; Jooste, Charl; McIsaac, Florent; Ruberl, Heather; Smet, Kim; Strzepek, Ken
Estimating the macroeconomic implications of climate change impacts and adaptation options is a topic of intense research. This paper presents a framework in the World Bank's macrostructural model to assess climate-related damages. This approach has been used in many Country Climate and Development Reports, a World Bank diagnostic that identifies priorities to ensure continued development in spite of climate change and climate policy objectives. The methodology captures a set of impact channels through which climate change affects the economy by (1) connecting a set of biophysical models to the macroeconomic model and (2) exploring a set of development and climate scenarios. The paper summarizes the results for five countries, highlighting the sources and magnitudes of their vulnerability --- with estimated gross domestic product losses in 2050 exceeding 10 percent of gross domestic product in some countries and scenarios, although only a small set of impact channels is included. The paper also presents estimates of the macroeconomic gains from sector-level adaptation interventions, considering their upfront costs and avoided climate impacts and finding significant net gross domestic product gains from adaptation opportunities identified in the Country Climate and Development Reports. Finally, the paper discusses the limits of current modeling approaches, and their complementarity with empirical approaches based on historical data series. The integrated modeling approach proposed in this paper can inform policymakers as they make proactive decisions on climate change adaptation and resilience.
Decarbonization Investment Strategies in an Uncertain Climate
(Wiley Periodicals LLC on behalf of American Geophysical Union, 2025-06-26) Bauer, Adam Michael; McIsaac, Florent; Hallegatte, Stéphane
The Paris Agreement established that global warming should be limited to “well below” 2 °C and encouraged efforts to limit warming to 1.5 °C. Achieving this goal presents a challenge, especially given (a) adjustment costs, which penalize a swift transition away from fossil fuels owing to, for example, skilled labor scarcity, and (b) climate uncertainty that complicates the link between emissions reductions and global warming. This paper presents a modeling framework that explores optimal decarbonization investment strategies with adjustment costs and climate uncertainty. The findings show that climate uncertainty impacts investment in three ways: (a) the cost of policy increases, especially when adjustment costs are present; (b) abatement investment is front-loaded relative to a scenario without uncertainty; and (c) the sectors with the largest changes in investment are those that are “hard-to-abate”, such as heavy industry and agriculture, each of which have high investment costs and annual emission rates. The longer learning about climate uncertainty is delayed, the more these impacts are amplified. Each of these effects can be traced back to the carbon price distribution inheriting a “heavy tail” when climate uncertainty is present. The paper highlights how climate uncertainty and adjustment costs combined lead to heightened urgency for near-term investments in decarbonization.
Global Socio-economic Resilience to Natural Disasters
(Washington, DC: World Bank, 2025-05-22) Middelanis, Robin; Jafino, Bramka Arga; Hill, Ruth; Nguyen, Minh Cong; Hallegatte, Stephane
Most disaster risk assessments use damages to physical assets as their central metric, often neglecting distributional impacts and the coping and recovery capacity of affected people. To address this shortcoming, the concepts of well-being losses and socio-economic resilience—the ability to experience asset losses without a decline in well-being—have been proposed. This paper uses microsimulations to produce a global estimate of well-being losses from, and socio-economic resilience to, natural disasters, covering 132 countries. On average, each $1 in disaster-related asset losses results in well-being losses equivalent to a $2 uniform national drop in consumption, with significant variation within and across countries. The poorest income quintile within each country incurs only 9% of national asset losses but accounts for 33% of well-being losses. Compared to high-income countries, low-income countries experience 67% greater well-being losses per dollar of asset losses and require 56% more time to recover. Socio-economic resilience is uncorrelated with exposure or vulnerability to natural hazards. However, a 10 percent increase in GDP per capita is associated with a 0.9 percentage point gain in resilience, but this benefit arises indirectly—such as through higher rate of formal employment, better financial inclusion, and broader social protection coverage—rather than from higher income itself. This paper assess ten policy options and finds that socio-economic and financial interventions (such as insurance and social protection) can effectively complement asset-focused measures (e.g., construction standards) and that interventions targeting low-income populations usually have higher returns in terms of avoided well-being losses per dollar invested.
Climate Policies are Path-Dependent: Implications for Policy Sequencing and Feasibility
(Washington, DC: World Bank, 2025-03-31) Mealy, Penny; Ganslmeier, Michael; Hallegatte, Stephane
Although the feasibility of introducing climate policies underpins global efforts to curb climate change, there has been limited analysis estimating the likelihood of introducing specific policies in different country contexts. Drawing on a dataset of climate policies introduced globally over the past 50 years, this paper explores patterns in climate policy adoption to quantify policy feasibility across countries. In constructing a ‘Climate Policy Space’ network based on the co-occurrence of policies across countries, the paper shows that climate policy adoption is path-dependent: countries are significantly more likely to introduce policies that are related to their prior climate policymaking experience. Exploiting this finding, the paper constructs empirically validated ‘Climate Policy Feasibility Frontiers’ which identify policies that are likely to be more feasible and could also increase the probability of the adoption of other policies. Complementing traditional cost-benefit analysis, feasibility frontiers can inform more realistic and strategic climate policy prioritization across countries.
Within Reach: Navigating the Political Economy of Decarbonization
(Washington, DC: World Bank, 2023-11-16) Hallegatte, Stéphane; Godinho, Catrina; Rentschler, Jun; Avner, Paolo; Dorband, Ira Irina; Knudsen, Camilla; Lemke, Jana; Mealy, Penny
Despite global commitments made through the Paris Agreement in 2015 to combat climate change, their translation into national policies has been slow, raising concerns about the feasibility of achieving climate targets. While policies face many obstacles, the political economy is one of the primary impediments to climate action, and urgency to reduce emissions makes slow and gradual approach increasingly insufficient. The report attempts to identify key political economy barriers and explore options to address them through the 4i Framework, considering how institutions, interests, ideas, and influence affect the political economy. The report offers a practical guide to help countries address political economy barriers when implementing climate policies with three prongs: (1) Climate Governance: governments can adapt their institutional framework, in ways that fit with the pre-existing political economy and moving from opportunistic and unstable to strategic and stable climate institutions. Establishing strategic climate governance institutions – such as climate change framework laws, long-term strategies, or just transition frameworks - can alter the political economy, set clear objectives, improve coordination across actors, and improve the ability to monitor progress and hold decisionmakers accountable. (2) Policy Sequencing: policies can be prioritized and sequenced based on dynamic efficiency, considering not only the economic costs and benefits, but also their feasibility and long-term impact on the political economy. The Climate Policy Feasibility Frontier tool can help identify policies that can overcome short-term political economy obstacles, and at the same time improve capacities and change the political economy to facilitate further climate action. (3) Policy Design and Engagement, considers the effective implementation of climate reforms by tactically navigating political economy constraints. This involves engaging citizens to create process legitimacy and reducing and managing distributional effects, not only across but also within income groups.
The Timing versus Allocation Trade-off in Politically Constrained Climate Policies
(Washington, DC: World Bank, 2024-11-18) Bauer, Adam Michael; Hallegatte, Stéphane; McIsaac, Florent
When leaders face political economy constraints, is it best to delay all decarbonization initiatives until a sectorally coordinated strategy can be implemented, or is it preferable to implement an approach where sectors’ decarbonization strategies are uncoordinated This question underscores a crucial trade-off – here coined the “timing versus allocation” trade-off – for politically constrained climate policymakers: (i) to sacrifice the optimal timing of climate policies to preserve the optimal allocation of emissions across economic sectors, or (ii) to preserve the optimal timing of abatement investment to the detriment of the allocation of emissions across sectors. This paper systematically explores this trade-off by presenting a modeling framework that elucidates the economic implications of various sub-optimal policy approaches to decarbonization that involve relaxing or delaying decarbonization efforts in a subset of sectors or economy-wide. The paper shows that the cost difference between an economy-wide, coordinated decarbonization strategy and an uncoordinated approach with heterogeneous carbon prices is smaller than the cost of delaying action and implementing a coordinated policy in the future. This implies that it is preferable to implement some policy in each sector, insofar as this is politically feasible, with less politically challenged sectors compensating with a marginal increase in policy ambition. The paper further elucidates how sectors with high annual emission rates, such as energy, are more costly to delay in comparison to their mid- to low-emission counterparts, such as industry, despite these sectors being nominally more costly sectors to decarbonize.
Natural Disasters, Poverty and Inequality: New Metrics for Fairer Policies
(Taylor and Francis, 2021-10-28) Walsh, Brian; Hallegatte, Stephane
Conventional risk assessments underestimate the human and macroeconomic costs of disasters, leading to inefficient risk management strategies. This happens because conventional assessments focus on asset losses, neglecting important relationships between vulnerability and development. When affected by a hazard, poor households take longer to recover from disasters and are more likely to face long-term consequences. Forced to manage trade-offs between essential consumption and reconstruction, these households are more likely to face persistent health or education costs. This chapter proposes a review of existing research into the natural disaster-poverty-inequality nexus and the various metrics that can be used to measure disaster impacts, such as recovery times, economic (income or consumption) losses, poverty incidence, inequality, and welfare or well-being losses. Each of these metrics provides a different perspective on disaster costs and suggest different spatial and sectoral priorities for action. Focusing on the concepts of well-being losses and socioeconomic resilience, this chapter shows how more comprehensive accounting of disaster impacts can better inform disaster risk management and climate change adaptation strategies and support their integration into development and poverty-reduction policies.
How Delayed Learning about Climate Uncertainty Impacts Decarbonization Investment Strategies
(Washington, DC: World Bank, 2024-03-29) Bauer, Adam Michael; McIsaac, Florent; Hallegatte, Stéphane
The Paris Agreement established that global warming should be limited to “well below” 2°C and encouraged efforts to limit warming to 1.5°C. Achieving this goal presents a challenge, especially given (i) economic inertia and adjustment costs, which penalize a swift transition away from fossil fuels, and (ii) climate uncertainty that, for example, hinders the ability to predict the amount of emissions that can be released before a given temperature target is exceeded. This paper presents a modeling framework that explores optimal decarbonization investment strategy when both adjustment costs and climate uncertainty are present. The findings show that climate uncertainty impacts investment in three ways: (i) the cost of policy increases, especially when adjustment costs are present; (ii) abatement investment is front-loaded relative to the certainty policy; and (iii) the sectoral allocation of investment changes to favor declining investment pathways rather than bell-shaped paths. The latter effect is especially pronounced in hard-to-abate sectors, such as heavy industry. Each of these effects can be traced back to the carbon price distribution inheriting a “heavy tail” when climate uncertainty is present. The paper highlights how climate uncertainty and adjustment costs combined result in a more aggressive least-cost strategy for decarbonization investment
Does Global Warming Worsen Poverty and Inequality? An Updated Review
(Washington, DC: World Bank, 2024-02-08) Trinh, Trong-Anh; Dang, Hai-Anh H.; Hallegatte, Stéphane
This paper offers an updated and comprehensive review of recent studies on the impact of climate change, particularly global warming, on poverty and inequality, paying special attention to data sources as well as empirical methods. While studies consistently find negative impacts of higher temperature on poverty across different geographical regions, with higher vulnerability especially in poorer Sub-Saharan Africa, there is inconclusive evidence on climate change impacts on inequality. Further analysis of a recently constructed global database at the subnational unit level derived from official national household income and consumption surveys shows that temperature change has larger impacts in the short term and more impacts on chronic poverty than transient poverty. The results are robust to different model specifications and measures of chronic poverty and are more pronounced for poorer countries. The findings offer relevant inputs into current efforts to fight climate change.
Counting People Exposed to, Vulnerable to, or at High Risk From Climate Shocks: A Methodology
(World Bank, Washington, DC, 2023-12-04) Doan, Miki Khanh; Hill, Ruth; Hallegatte, Stephane; Corral, Paul; Brunckhorst, Ben; Nguyen, Minh; Freije-Rodriguez, Samuel; Naikal, Esther
Based on global datasets, 4.5 billion people were exposed to extreme weather events (flood, drought, cyclone, or heatwave) in 2019, an increase from 4 billion in 2010. Among exposed people in 2019, 2.3 billion people lived with less than $6.85 per day and about 400 million lived in extreme poverty (on less than $2.15 per day). This paper presents a methodology to estimate the number of people who are at high risk from extreme weather events, defined as the people who are exposed to these events and highly vulnerable to them. Vulnerability is proxied by a set of indicators measuring (1) the physical propensity to experience severe losses (proxied by the lack of access to basic infrastructure services, here water and electricity) and (2) the inability to cope with and recover from losses (proxied by low income, not having education, not having access to financial services and not having access to social protection). Estimates from 75 countries for which data on all indicators are available suggest that, in 2019, 42 percent of the total population (and 70 percent of people exposed) are at high risk from extreme weather shocks, if one indicator is enough to be considered as highly vulnerable. If high vulnerability is defined based on being vulnerable on two dimensions or more, then 12 percent of the total population (and 20 percent of people exposed) are at high risk from extreme weather shocks. The trend between 2010 and 2019 can be explored in a subset of countries covering 60 percent of the world population. In these countries, even though the population exposed to extreme weather events has been increasing, the number of people at high risk has declined. The exception is Sub-Saharan Africa where the number of people at high risk has increased between 2010 and 2019.