A study published in Nature Climate Change (31 August) notes that “high extirpation rates” are particularly expected for tropical species in the Coral Triangle — the recognised centre of global marine biodiversity that spans the waters of Indonesia, Malaysia, Papua New Guinea, the Philippines, Solomon Islands and Timor Leste.
Researchers calculated how the overall distribution of 12,796 marine species and the composition of their communities would change using two climatic models of the Intergovernmental Panel on Climate Change called the representative concentration pathways (RCP) — RCP 4.5 and RCP 8.5.
The RCP 4.5 model assumes that greenhouse gas emissions will reach their maximum point around 2040. In the RCP 8.5 model, they grow constantly until 2100.
The temperatures associated with the RCP 8.5 model would affect more species and have a wider geographical extent than those of RCP 4.5. In the RCP 8.5 scenario, changes would occur for the remainder of the century. Under RCP 4.5, changes would be concentrated in the first half of the century.
In RCP 8.5, the losses are mostly in the tropics, especially in the central Indo-Pacific (Northern Mariana Islands, Philippines, Taiwan and China). Many other marine zones, such as those around 30-40 degrees north and south of the equator, would gain more species than they have lost.
The extinction of some species and the migration of others due to ocean warming would even out the composition of marine communities in different regions.
For Latin America and the Caribbean, the study found clear differences between the two climatic models.
“For 2100, the RCP 4.5 projections indicate net losses of species mainly around Florida and Cuba in the Caribbean, the Central American Pacific coast and the Argentine Atlantic coast. There would be net increases in the rest of the Caribbean and around the South American coast,” says Jorge García-Molinos, marine ecologist at the Scottish Association for Marine Science, and the lead author of the study.
“On the other hand, the RCP 8.5 model predicts net losses of biodiversity in practically the whole of the Caribbean and on the coasts of Central and South America north of Ecuador and northern Brazil,” he adds.
García-Molinos tells SciDev.Net that determining how marine species would redistribute in response to climate change requires detailed studies of each species and each geographical zone, which include temperature change, type of habitat, availability of resources and competition between species.
As species move, they will pass from one country's territorial waters to another. This will require new agreements on joint exploitation and access to fisheries, he says.
Amanda Bates, a researcher at the University of Southampton, United Kingdom, commends the study’s “overall scale of analysis, which includes many different species”.
“This approach allowed the researchers to predict the effect of climate change on marine biodiversity, which will be useful in determining priorities for conservation and for better management and protection of our natural resources,” Bates notes.
>Link to the abstract in Nature Climate Change
This article is based on an article originally published by SciDev.Net's Latin America and Caribbean desk.