Is the extinction of Pacific Islands species inevitable due to climate change?

A team of researchers from the Ecology, Systematics and Evolution laboratory (ESE – Université Paris-Saclay, CNRS, AgroParisTech) conducted a study to measure the impact of climate change on these unique island ecosystems. Island biodiversity is likely to disappear by 2050 if no specific measures are taken to preserve it, particularly in six Pacific archipelagos.

Ever seen a Pacific flying fox - a large bat with a reddish coat? Or a babyrousa from the warthog family - with pleated skin? Probably very few people, because these mammals come from the Pacific Ocean islands, a very restricted geographic area. This is called insular endemism. Like thousands of other island species, these endemic mammals contribute to global terrestrial biodiversity. This exceptional biodiversity is now threatened by climate change. In the next 30 years, ecosystems and islands will undergo rapid change, causing a sharp decline in the diversity of local species. The vulnerability of island ecosystems must be assessed so that strategies for the preservation of species - particularly endemic - can be developed.

Despite the growing number of studies assessing the impact of climate change on biodiversity, few focus on island ecosystems. Those that do are limited to the impact of climate change, and do not investigate the reaction of organisms and ecosystems to environmental change. For example, given the geographic isolation of island species, they are unable to migrate to another place with more appropriate living conditions, for more food or a warmer climate for example. This considerably reduces their capacity to adapt to the threat of climate change. To increase the understanding of this threat and assess the potential impact, researchers from the Ecology, Systematics and Evolution laboratory (ESE – Université Paris-Saclay, CNRS, AgroParisTech) studied island vulnerability with over 850 endemic mammals.

Increased vulnerability in the Pacific Islands

In 2007, the IPCC (Intergovernmental Panel on Climate Change) established a vulnerability criterion to classify species and identify the most vulnerable. Vulnerability depends on a specie’s level of exposure to the threat, its sensitivity or resistance to climate change, and its adaptive capacity.
Based on 2050 climate predictions, ESE researchers measured the vulnerability of over 300 islands based on 873 endemic mammal species. The study predicts that by 2050, all the islands and archipelagos will be suffering from a certain degree of vulnerability to climate change, but with spatial differences. For example, the most vulnerable regions are in the Pacific Ocean, particularly in the New Hebrides, the Bismarck Archipelago, the Malay Archipelago, New Caledonia, the Solomon Islands and the island of Sulawesi.

The difference in vulnerability is explained by the high sensitivity and low adaptive capacity of endemic ecosystems and mammal species. Their special diets and long generation make them less adaptable to climate change. Climate change menaces these species with extinction.

Once again, this study highlights the alarming future for terrestrial ecosystems due to climate change. Without a major conservation strategy, several island species are likely to disappear within 30 years. Yet less carbon fooprint and more preserved areas could lead to quite a different outcome. Is there hope for the Pacific flying fox and the babyrousa?
 

Référence :
Leclerc, C., Courchamp, F., & Bellard, C. Future climate change vulnerability of endemic island mammals. Nature Communications, 11, 4943 (2020).