by Alexander Birk

Island biodiversity is of paramount importance on a global scale. The islands of the world contain twenty percent of all terrestrial plant and animal species. In addition the rate of endemic species on islands is much greater than on main lands, and island species are facing many threats. Over half of the most recent extinctions on the planet come from species inhabiting islands. In addition one third of all terrestrial species that are currently threatened with extinction are island-dwelling species (Couchamp et al. 2014).

The threats to island biodiversity have not gone unnoticed, there are increasing island conservation efforts in place today. Most of these efforts consist of conservation of habitat, and also include invasive species removal, but the threat of sea level rise has not be as thoroughly considered, even though it is one of the most widely accepted effect of climate change. With the current rates of climate change sea levels are expected to rise anywhere from 0.26 to 2.3 meters by 2100, some islands will endure dramatic habitat change. Up to 19 percent of 4,500 island biodiversity hotspots could be completely submerged. This would mean that up to 300 endemic species would be threatened with extinction. There are currently 604 islands that have ongoing projects to help support endangered species survival. It is predicted that twenty six of those islands would be completely submerged if sea level rose one meter. This would not only inevitably wipe out a great number of island species, but it would also render all of the previous conservation efforts meaningless.

Islands becoming completely submerged is not the only issue as sea levels rise. The islands that do not become completely submerged will surely become smaller. This will push the native species closer together, which will in turn create more competition and possibly more extinctions. Areas inhabited by humans will be pushed inward as well, constricting even more space for native species. One option for protecting these island species would be translocation. However so many species are specifically adapted to their island environment it would be a challenge to find another place for them to thrive (not to mention the consequences of island species invading and disrupting other ecosystems). If the decision is not to move them, then the risk becomes losing even more island species to extinction.

Franck Courchamp, Benjamin D. Hoffmann, James C. Russell, Camille Leclerc, Céline Bellard. 2014. Climate change, sea-level rise, and conservation: keeping island biodiversity afloat. Trends in Ecology & Evolution. doi:10.1016/j.tree.2014.01.001

http://www.sciencedirect.com/science/article/pii/S0169534714000147

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