Air Quality Penalty in Southeast Asia Driven by AMOC Slowdown

The Atlantic Meridional Overturning Circulation (AMOC) regulates Earth's climate by redistributing heat and freshwater across the Atlantic Ocean. While accelerating Arctic melt is expected to weaken the AMOC, its implications for atmospheric composition remain poorly understood. Here we present the first global assessment of atmospheric responses to a 60% AMOC decline using a chemistry–climate model. AMOC weakening slows the monsoon system and shifts the Intertropical Convergence Zone, reducing cloud cover and deep convection over Southeast Asia. These changes modify surface radiation, lightning‐produced NO x , and biogenic volatile organic compound emissions, reshaping tropospheric chemistry and increasing surface ozone. Reduced precipitation also decreases wet deposition efficiency, allowing aerosol particles to accumulate and increasing surface . Our findings identify a climate–chemistry pathway through which ocean circulation tipping points can exacerbate air‐quality risks in populated regions.