Estimating countries' additional carbon accountability for closing the mitigation gap based on past and future...

Area of Science:

• Climate Science
• Environmental Economics
• International Relations

Background:

• Global carbon budget allocation for climate change mitigation is complex.
• Existing methods struggle to quantify fair national shares of remaining emissions.
• Historical emissions and future pathways are key factors in determining responsibility.

Purpose of the Study:

• To introduce and apply a novel indicator, "additional carbon accountability," for quantifying national responsibility in climate mitigation and CO2 removal.
• To assess countries' contributions to closing the global mitigation gap beyond their own targets.
• To analyze the impact of historical emissions (carbon debts) and future emission pathways on national accountability.

Main Methods:

• Developed the "additional carbon accountability" indicator.
• Utilized an equal cumulative per capita emissions approach.
• Calculated carbon debts since 1990 and future claims based on emission pathways.
• Assessed accountability for countries with a positive total excessive carbon claim.

Main Results:

• The global carbon budget for limiting warming to 1.5°C (50% probability) is exceeded by 576 Gigatonnes of fossil CO2.
• The United States and China show the highest overall additional carbon accountability.
• The United Arab Emirates and Russia have the highest per capita additional carbon accountability.
• Assumptions regarding carbon debts significantly influence country-specific results.
• Financial capacity for accountability differs, with challenges for Iran, Kazakhstan, and BRICS+ members compared to G7 nations.

Conclusions:

• Additional carbon accountability provides a framework for fairer distribution of climate mitigation and CO2 removal responsibilities.
• The indicator highlights significant disparities in national contributions and capacities to address the climate crisis.
• Policy implications include the need to consider historical responsibility and future emission trajectories in international climate negotiations.