The Norwegian coastline spans from 58°N to 71°N and exhibits an environmental gradient with decreasing temperatures from south to north. The great scallop (Pecten maximus) is distributed along the Norwegian coastline up to 67°N, where the distribution is documented through monitoring by underwater video and scientific diving. Since the mid-2000s, monitoring has revealed a northward shift, where small populations of great scallops have established themselves beyond the previous distribution boundaries along the coastline and in the mid-western part of the Lofoten Islands at 68°N. The northward expansion of the great scallops’ distribution is believed to be limited by low temperatures. However, over the past 15 years, coastal water temperatures have increased by approximately 1°C. Although a 1-degree temperature increase may seem modest, it reduced the time during winter with temperatures below 4°C from three to one month at the coastal station Skrova at 68°N. As the great scallop’s preference for warm water is widely documented, and the timing of the northward shift seems to occur at the same time as the warmer waters are observed, we believe that the temperature increase is the main explanation for the observed northward shift on established populations of P. maximus.