Persistent inequality in economically optimal climate policies.

Area of Science:

• Climate economics
• Integrated assessment modeling
• Socioeconomic impacts of climate change

Background:

• Benefit-cost analyses of climate policies often yield conflicting results.
• Existing integrated assessment models (IAMs) inadequately address regional heterogeneity and inequality, critical factors for social welfare.

Purpose of the Study:

• To develop and utilize a comprehensive benefit-cost model incorporating regional heterogeneity and country-level economic damages.
• To compare self-interested versus cooperative behavior of nations under various socioeconomic and climate scenarios.

Main Methods:

• Developed a multi-region (50+) benefit-cost model calibrated with emissions and mitigation cost data from detailed-process IAMs.
• Incorporated country-level economic damages and analyzed scenarios with varying socioeconomic development, climate impacts, and intertemporal/inequality preferences.

Main Results:

• Without international cooperation, global temperature increases, though less than in typical reference scenarios.
• Cooperative behavior stabilizes global temperature within the Paris Agreement goals (1.80°C by 2100).
• Significant economic inequality persists, with the top income decile's ratio to the bottom decile increasing by 117% compared to a no-climate-impact scenario, even under optimal pathways.

Conclusions:

• International cooperation is crucial for mitigating climate change and achieving temperature goals.
• Climate policies, even when economically optimal, may exacerbate existing economic inequalities without specific interventions.
• Future research should focus on integrating inequality reduction measures into climate policy frameworks.