East Asian aerosol cleanup has likely contributed to the recent acceleration in global warming

A new study leveraging Earth System Models indicates that East Asian efforts to reduce air pollution, specifically a 75% reduction in sulfate emissions since 2010, have significantly contributed to the accelerated global warming observed in the past decade. This aerosol cleanup has unmasked greenhouse gas-driven warming, adding approximately 0.07°C to global mean temperatures and accounting for a substantial portion (0.05°C/decade) of the 0.06°C/decade increase in the global warming rate since 2010, with pronounced effects in East Asia and the North Pacific. This highlights an unintended, yet material, climate consequence of regional air quality improvements.

Analysis

A recent scientific study using eight Earth System Models provides compelling evidence that China's successful efforts to reduce air pollution have unintentionally accelerated global warming since 2010. The sustained 75% reduction in East Asian sulfate (SO2) emissions, a pollutant with a known atmospheric cooling effect, has unmasked underlying greenhouse gas-driven warming. This has resulted in a quantifiable global mean temperature increase of 0.07 ± 0.05 °C. The study attributes a warming rate of 0.05 °C/decade to this aerosol cleanup, accounting for a significant portion of the observed acceleration in the global warming rate from 0.18 °C/decade (1980-2009) to 0.25 °C/decade (2010-2023). The geographical pattern of this induced warming is concentrated over East Asia and the North Pacific, which corresponds with observed temperature anomalies and satellite-measured changes in the Earth's radiative balance. As the potential for further SO2 reductions in this region is now limited, this specific driver of accelerated warming is expected to become less prominent, shifting the focus to other factors like greenhouse gas emissions and aerosol changes from other regions.

Key Decisions for Investors

• Investors should update physical climate risk models to account for the now-quantified impact of aerosol reduction, which validates a faster near-term warming trajectory and increases the probability of associated physical risks.
• ESG and sustainable investment frameworks must evolve to assess the complex trade-offs of environmental policies, as this analysis demonstrates that positive actions on air quality can have material, negative consequences for global climate targets.
• Portfolio managers should now focus on greenhouse gas emission trajectories and future aerosol policies, particularly from India and the global shipping sector, as these will become the dominant variables for forecasting warming rates now that the acceleration from East Asian cleanup is likely to plateau.