Climate change: Risk to marine life from contrasting emissions assessed

An evaluation of climate risks faced by nearly 25,000 marine species reveals that almost 90% are at high or critical risk under high emissions scenarios to 2100. The findings, presented in a modelling study in Nature Climate Change, could help prioritize conservation efforts.

Climate change is driving ecological change and biodiversity loss, necessitating strategies to understand risks in order to prioritize responses. For maximum management value, climate risk assessments should be empirically rooted and spatially explicit and consider changing climate conditions, as well as the susceptibility and adaptivity of species.

Daniel Boyce and colleagues evaluate the predicted climate risk of 24,975 marine species worldwide, including animals, plants, chromists, protozoans and bacteria that inhabit the upper 100 metres of oceans. Under high greenhouse gas emission scenarios (IPCC shared socio-economic pathway scenario (SSP) 5-8.5), by 2100, almost 90% of the species are predicted to experience a high or critical risk of not being able to survive in their current habitat across an average of 85% of their geographical distribution. The authors reveal that one-tenth of the ocean has areas of combined high climate risk, endemism (where species are found in few locations) and extinction threat to species. Threats are greatest for larger predator species, especially those harvested for food (such as species of pufferfish, tunas and sharks) and in low-income countries with a high dependence on fisheries. Mitigating emissions (under an SSP1-2.6 scenario) by 2100 could reduce the risk for nearly all species examined, enhance ecosystem stability and disproportionally benefit food-insecure populations in low-income countries, the team predicts.

The authors conclude that these findings could be used to prioritize the conservation of vulnerable marine species and ecosystems as part of climate-oriented management strategies, considering the importance of geographical variation and habitat location.