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More losers than winners for Southern Ocean marine life in a warmer future.

A study of the marine invertebrates living in the seas around Antarctica reveals there will be more ‘losers’ than ‘winners’ over the next century as the Antarctic seafloor warms. The results are published in the journal Nature Climate Change.

A team at British Antarctic Survey (BAS) examined the potential distribution of over 900 species of shelf-dwelling marine invertebrates under a warming scenario produced by computer models. The authors used the known distributions of 963 benthic species with ≥20 records, from <1,000 m depth, from south of 40 °S. The records came from the SCAR Biogeographic Atlas of the Southern Ocean & OBIS. The climate models used were an ensemble of 19 different models from the CMIP5 database of mean seafloor temperatures for 2099 under the IPCC RCP8.5 scenario (the most extreme of all the scenarios where emissions continue to rise throughout the 21st century).

Southern Ocean seafloor water temperatures are projected to warm by an average of 0.4 °C over this century with some areas possibly increasing by as much as 2°C. The team conclude that, while some species in some areas will benefit, within the current century, warming temperatures alone are unlikely to result in wholesale extinction or invasion affecting Antarctic seafloor life. However, 79% of Antarctica’s endemic species do face a significant reduction in suitable temperature habitat (an average 12% reduction). Their findings highlight the species and regions most likely to respond significantly (negatively and positively) to warming and have important implications for future management of the region.

Reference: Griffiths, Huw J., Andrew JS Meijers, and Thomas J. Bracegirdle. "More losers than winners in a century of future Southern Ocean seafloor warming." https://www.nature.com/articles/nclimate3377.