A recent report published in the journal Nature Conservation has found that sea levels are rising at a higher rate than they have for thousands of years, putting many islands and the species living on them at risk.
Global climate change is negatively affecting the Earth and its oceans in many ways, and these impacts are predicted to be the greatest cause of future species extinctions. The increasing temperature on Earth is melting the sea ice at the North and South Poles, which is increasing the amount of water in the oceans. The temperature of the ocean is also increasing, which raises the volume of the seawater due to the molecules requiring more space to move. “Sea level rise is one of the most certain consequences of global warming, yet it remains the least studied,” the study said. “Potential effects of sea level rise are of considerable interest because of its potential impact on biodiversity and society.”
Of the 180,000 islands on Earth, all low-lying islands are particularly at risk and it is thought that over 10,000 of them could disappear, along with the species that live on them, if the sea level rise predictions are correct. Islands are home to a much higher proportion of endemic species than mainland areas, with the entire population of the Alaotran gentle lemur, New Caledonia blossom bat, Seychelles frog and thousands of other species being found on just one island, or a small group of islands. The submersion of numerous islands will not just impact fauna and flora, with human populations living in coastal areas also being forced to move inland or relocate completely in response to the rising sea levels, and coastal industries being lost.
New Caledonia and French Polynesia are thought to be the islands most at risk of disappearing under water, with islands in the Caribbean and Mediterranean and those in close proximity to Guyana and Madagascar also under threat. The study found that, after a predicted sea rise of between 0.5 and 2.3 metres, more than 30 percent of the totally submerged islands would be in New Caledonia, 30 percent in French Polynesia and 10 percent in the Mediterranean, with the rest occurring in other regions.
The authors of the study said, “Considering their important contribution to global biodiversity and the threat of sea level rise for future biodiversity of some of these islands, there is an urgent need that islands feature prominently in global and regional conservation prioritisation schemes.” Less than 5 percent of the Earth’s land area is represented by islands, although they are home to around 20 percent of the world’s bird, reptile and plant species, as well as other fauna. Of all known extinctions, 80 percent have occurred on islands, and although climate change may be partially to blame, the negative effects of invasive species, deforestation, over-collection and various other threats are more prevalent in island ecosystems than on the mainland and have much greater and more severe impacts on island species.
Find out more about the effects of climate change on animal and plant species
Find out more about the conservation of islands
Hannah Mulvany, ARKive Content and Outreach Officer