Monday, June 18, 2012

Sea level rise hidden impact on Biodiversity and Habitat loss

A new scientific study published in Global Change Biology raises alarm bells about global climate change and the secondary impact of sea level rise on habitat loss and species biodiversity, especially in the Asian and Pacific regions.

We already know that Climate change and habitat loss threaten biodiversity with the extinction rate underestimated and that Biodiversity is a crucial climate change buffer for ecosystem and cultural diversity. Scientists have warned that biodiversity is declining rapidly throughout the world, describing the loss of species as the 6th mass extinction event on the earth. Tropical insects may already be an extreme risk of extinction with just moderate increases in temperature. Now the secondary effects of sea level rise could also have a devastating impact on biodiversity.

With sea levels forecast to rise 1 to 2 metres this century, this will have a primary impact on coastal habitat and biodiversity. But as human populations also migrate to higher ground, there will be some substantial changes in land use resulting in impacts on habitat loss and biodiversity. In more populated regions the secondary impacts on habitat and species biodiversity may be equal to or larger than the primary impacts.

The study by researchers from the Konrad Lorenz Institute of Ethology of the University of Veterinary Medicine, Vienna and Ecoinformatics and Biodiversity Group of Aarhus University, Denmark looked at the impact of sea level rise on more than 1200 islands in the Southeast Asian and Pacific regions. The researchers assessed that:
  • between 3 and 32 percent of the coastal zone of these islands could be lost from primary effects depending upon the sea level rise scenario
  • around 8 to 52 million people could become flood refugees
  • Secondary range loss effects may equal or even exceed primary effects for at least 10-18 percent of the sample mammals in a moderate scenario and for 22-46 percent in a maximum scenario.
  • species in Oceania are more vulnerable to primary effects
  • species in Indo-Malaysian islands - which may be affected by 7 to 48 million sea-level rise refugees - are more at risk from secondary effects.
"Our findings suggest that to accurately identify ecologically vulnerable regions and species, it is crucial to consider secondary effects of sea-level rise," said Florian Wetzel from the Konrad Lorenz Institute of Ethology. "We are aware that we are dealing with projections, and that this is a controversial topic, but we are convinced that assessments of sea-level rise should incorporate such secondary effects, or else risk under-estimating the consequences of global climate change on biodiversity and ecosystems" said Dustin Penn from Aarhus University, Denmark.

Image caption: The Indonesian island of Pulau Bintan in a simulated sea-level rise (SLR) scenario of 3 meters. Blue stripes: flooded area; Red: densely populated or intensive agricultural area; Green: potential habitat of the Rajah Spiny Rat (Macromis rajah; Graphics by Vetmeduni Vienna/Beissmann/Wetzel)

The study - Future climate change driven sea-level rise: secondary consequences from human displacement for island biodiversity - says in part in the article abstract:

we assessed the consequences of primary and secondary SLR effects from human displacement on habitat availability and distributions of selected mammal species. We estimate that between 3-32% of the coastal zone of these islands could be lost from primary effects, and consequently 8-52 million people would become SLR refugees. Assuming that inundated urban and intensive agricultural areas will be relocated with an equal area of habitat loss in the hinterland, we project that secondary SLR effects can lead to an equal or even higher percent range loss than primary effects for at least 10-18% of the sample mammals in a moderate range loss scenario and for 22-46% in a maximum range loss scenario. In addition, we found some species to be more vulnerable to secondary than primary effects. Finally, we found high spatial variation in vulnerability: species on islands in Oceania are more vulnerable to primary SLR effects, whereas species on islands in Indo-Malaysia, with potentially 7-48 million SLR refugees, are more vulnerable to secondary effects. Our findings show that primary and secondary SLR effects can have enormous consequences for human inhabitants and island biodiversity, and that both need to be incorporated into ecological risk assessment, conservation, and regional planning.

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