The North Atlantic Oscillation (NAO) has contributed to the cooling of the subpolar North Atlantic over the past century. The NAO intensifies surface winds, leading to heat loss from the ocean, which cools the region by 0.26 degrees per century. This explains 67% of the observed cooling trend. Changes in atmospheric circulation, including the NAO and the East Atlantic Pattern, account for 44% of the cooling trend, alongside ocean circulation changes.