The effect of anthropogenic aerosols on lightning is one of the least understood aspects of human-induced climate change. Global aerosol clearly diminished during the COVID pandemic by 7.6%. A pronounced decrease in global lightning activity in the range 3.0%-5.8% is identified from various detection systems during this natural experiment. The Maritime Continent lightning chimney shows the largest reduction of 7.0% in aerosol accompanied by a lightning drop of 15%. The COVID period in 2020 also experiences a transition from pre-COVID El Niño to a strong and sustained La Niña. Compensation for ENSO forcing of lightning activity is implemented to disclose the distinct responses of three global lightning chimneys to competing thermodynamic and aerosol effects. Our observational findings indicate a marked influence of aerosol on a global scale by virtue of the extraordinary COVID-induced aerosol alteration.