Major heat wave in the North Atlantic had widespread and lasting impacts on marine life.

Abstract

Marine heat waves (MHWs) are increasing in frequency and intensity, but wider effects are unexamined in the North Atlantic, and there are uncertainties regarding the spatial scale, magnitude, and persistence of MHWs' impacts on ecosystems. We show that a sudden and strong increase in the frequency of MHWs in and after 2003 was linked to widespread and abrupt ecological changes. This upheaval spanned multiple trophic levels, from unicellular protists to whales. Every examined region showed a reorganization from species adapted to colder, ice-prone environments to those favoring warmer waters and the event's impacts altered socioecological dynamics. This review provides evidence for large-scale connectivity across ocean basins. However, it reveals that the magnitude of ecological impacts seems to vary among events highlighting key knowledge gaps for predicting ecosystem responses to MHWs. Understanding the importance of the subpolar gyre and air-sea heat exchange will be crucial for forecasting MHWs and their cascading effects.