Climate vulnerable fish communities are also most exposed to human pressures

The climate crisis has far-reaching consequences on the health and integrity of ecosystems1. More specifically, warming causes shifts in species distributions and interactions, ultimately altering the structure and functioning of ecosystems2–4. The response and sensitivity of marine organisms to climate change have commonly been assessed using temperature-based indices5–8. However, the exclusive focus on temperature overlooks other key environmental stressors affecting marine life, such as deoxygenation and freshening9–11. Here we assess the sensitivity of marine organisms to multiple environmental factors by estimating the single and cumulative Environmental Safety Margins (ESM) of marine fish communities throughout the North Atlantic and Northeast Pacific over the past 30 years. We find ESMs and their underlying stressors to differ between ocean provinces with generally unsafe conditions in lower latitudes and estuarine systems. Furthermore, we demonstrate regional differences in the relative importance of environmental stressors, with temperature, oxygen limitation and low salinities constraining species and communities differently across provinces. The areas deemed most unsafe to climate change are also facing the highest cumulative pressures from fishing, shipping and land-based stressors. These results highlight that climate vulnerable fish communities are also most exposed to human pressures revealing an urgent need for improved conservation efforts.