An increase in the North Atlantic summertime sea surface temperature compared to wintertime over the last five decades has been attributed to a corresponding decrease in anthropogenic sulfur dioxide (SO2) emissions from North America, due to reduced aerosol-radiation shielding. However, the pathways (direct vs indirect aerosol effects) and seasonality of radiative forcing due to sulfate aerosol remain uncertain. In this work, we estimate the climatology of sulfate aerosols over the North Atlantic Ocean (NATL), attributable to changes in anthropogenic SO2 emissions from North America. We use the Community Earth System Model with fixed natural but varying anthropogenic SO2 emissions in the 1970 to 2010 period. We find that a 50% reduction in SO2 emissions from 1970 to 2000 led to a 35% decrease in sulfate aerosol concentrations and burden over the NATL. This decline in sulfate aerosols led to an annual-average surface shortwave heating of ~1.5 W/m² over the NATL, particularly during summer due to a reduction in their peak concentrations. Aerosol-cloud interactions drive most of this heating. Summer forcing is about 2.5 W/m2 compared to 0.5 W/m2 in wintertime.