Energy-intensive adaptation partially offsets climate-driven labour productivity losses but at rising welfare costs

Technical Summary: Energy-intensive adaptation partially offsets climate-driven labour productivity losses but at rising welfare costs

Problem Statement
Climate change poses a significant threat to the global labour force, as rising temperatures undermine work capacity and health, leading to reductions in labour productivity and increases in heat-related morbidity. While existing literature has established the magnitude of heat-induced productivity losses, particularly in outdoor sectors like agriculture and construction, and separately documented the rising demand for cooling energy as an adaptation strategy, a critical gap remains. Previous studies have generally treated these two channels in isolation: heat impacts are analyzed without closing the loop to the energy system, and cooling demand is often modeled without linking it back to aggregate economic output and productivity. Consequently, the feedback mechanisms between temperature extremes, endogenous energy consumption for adaptation, and long-term economic welfare remain underexplored. This study addresses the need to understand how energy-intensive adaptation (specifically air conditioning) interacts with climate-driven labour losses, assessing whether such adaptation effectively offsets damages or leads to rising welfare costs and potential maladaptation.

Methodology
The authors develop a unified modelling framework based on the WITCH Integrated Assessment Model (IAM), extending it to 2100 to explicitly integrate three endogenous mechanisms:

1. Labour Productivity Shocks: Temperature extremes (Cooling Degree Days above 18°C, CDD18, and Heating Degree Days below 18°C, HDD18) are linked to total factor productivity (TFP). The model distinguishes between high-exposure (outdoor) and low-exposure (indoor) labour sectors. Empirical estimates derived from a country-year panel dataset (1970–2019) calibrate the relationship between temperature, energy use, and productivity, revealing that adaptation energy mitigates losses primarily in low-exposure sectors.
2. Endogenous Energy Demand: The model simulates autonomous and planned adaptation where households and firms increase energy consumption for cooling. This is modeled through both an "intensive margin" (increased usage of existing technology) and an "extensive margin" (adoption of new technology, e.g., purchasing AC units).
3. Adaptation Costs and Feedback: The framework accounts for the capital accumulation of air-conditioning stock and the associated energy and investment costs. These costs are subtracted from GDP, allowing the model to assess the net welfare impact of adaptation.

The study evaluates three adaptation scenarios (Low, Medium, High) reflecting varying levels of adaptive capacity and income-driven technology adoption, comparing them against an Impact Scenario (IS) where cooling capital is held at historic levels.

Key Contributions

1. Integrated Assessment: The paper provides a unified dynamic modelling framework that simultaneously assesses sector-specific heat impacts (distinguishing outdoor vs. indoor labour) and the role of non-residential cooling energy in offsetting these losses, a departure from studies that analyze these channels in isolation.
2. Non-Residential Projections: By explicitly modelling capital accumulation in cooling technologies alongside sectoral energy demand, the study offers long-term projections of non-residential cooling needs and their economic role, extending beyond the residential sector focus of previous literature.
3. Net Welfare Quantification: The study quantifies the net effect of climate-induced heat stress on aggregate GDP, assessing the extent to which energy-based adaptation mitigates losses while accounting for the rising costs of adaptation investment and energy consumption.

Results

• Climate-Driven Losses and North-South Divergence: Under a moderate (SSP2) warming scenario, climate-induced labour impacts generate substantial losses. By 2100, global GDP is projected to fall by 2.9% annually relative to the baseline. The Global South faces severe losses (average -5.9% GDP by 2100), particularly in outdoor-intensive economies like India (-11.65%) and Sub-Saharan Africa (-8.78%). Conversely, high-income regions in the Global North, benefiting from reduced cold penalties (negative Net Thermal Balance), experience productivity gains (average +1.8% GDP).
• Role of Economic Structure: The magnitude of losses is not solely determined by thermal exposure but by economic structure. Economies with a higher share of outdoor labour convert the same thermal balance into larger productivity losses because outdoor workers lack a cooling adaptation channel.
• Partial Offset by Adaptation: Energy-intensive adaptation partially reverses these losses. In the Global South, adaptation offsets 18–40% of the gross productivity loss depending on the scenario. However, the global productivity remains negative even under high adaptation.
• Diminishing Returns and Maladaptation: The study identifies a concave, saturating response curve for adaptation.
  • Global North: In cold-relief dominated regions, additional cooling energy yields diminishing marginal returns. Because the protective effect saturates (around 5–10 GJ per capita) while costs accumulate, high adaptation levels can actually reduce net GDP compared to low adaptation in these regions (e.g., Canada, EU).
  • Energy-Rich South: A similar saturation occurs in hot but energy-rich Southern economies (e.g., MENA). Despite high heat exposure, these regions operate on the flat arm of the response curve; further energy deployment adds cost without proportional productivity gains, leading to potential maladaptation.
  • Energy-Poor South: In heat-exposed, energy-poor regions (e.g., Sub-Saharan Africa), the marginal return on cooling energy remains high, but access is the binding constraint.
• Inequality: Adaptation reshapes the distribution of impacts. While it narrows the North-South GDP gap slightly, it does not eliminate the divergence. The "cost-effective frontier" of adaptation is region-specific, lying at lower intensity in the North and higher intensity in the South, but bending back in energy-rich Southern outliers.

Significance and Claims
The paper claims that energy-intensive adaptation delivers real but bounded and unevenly distributed relief. It never fully neutralizes the underlying climate signal. The study argues that the effectiveness of adaptation is governed less by the need for cooling and more by where a region sits on a saturating response curve.

The authors conclude that the North-South divide in climate impacts is "doubly regressive": the energy-poor South is denied high-return adaptation it desperately needs, while the energy-rich North may afford adaptation whose marginal returns have already vanished. Consequently, the paper posits that cooling energy should be understood not as a universal solution but as a targeted instrument with a region-specific optimal dose. Policy implications suggest that a "one-size-fits-all" push for adaptation energy would be regressive; instead, efforts should focus on energy access for the heat-exposed, energy-poor South where marginal productivity returns are highest, coupled with specific strategies for outdoor labour that space cooling cannot protect.