Escalating climate change impacts on species prompt new review
Amajor paper co-authored by the International Union for Conservation of Nature (IUCN) published recently reviews the relatively new ield of assessing species’ vulnerability to climate change, as experts warn that time is running out for many species. The paper, “Climate change vulnerability assessment of species”, was published in the journal WIREs Climate Change.
The paper also provides guidance on carrying out rigorous assessments, which take into account the broad range of ways in which climate change may become a threat to species. This work will help better integrate climate change threats into the IUCN Red List of Threatened SpeciesTM. The paper is authored by eighteen leading scientists, all of them members of the IUCN SSC Climate Change Specialist Group.
The impacts of climate change on species range from rising sea levels destroying habitats to shifts in the availability of food, as in the case of many seabirds. The authors stress that assessments should identify the full range of pressures that plants, animals and fungi face from a changing climate, and then choose suitable assessment methods.
There is growing evidence of the increasing likelihood of extinctions due to climate change, with the irst documented extinction, of the Bramble Cay mosaic-tailed rat, recorded in 2016. Anthropogenic climate change already affects species at most latitudes and in most habitat types, including coral reefs, forests, tundra, deserts, grasslands and wetlands, according to the paper. Climate change is listed as a threat for almost a ifth of species threatened with extinction on the IUCN Red List.
To date, climate change vulnerability assessments have tended to overlook species that have small distributions, such as many sub-Saharan amphibians, and to underestimate risk for those declining in number or distribution, according to the paper. This is of particular concern as these types of species are also at greatest risk of extinction, the authors warn.
The authors contributed expertise from their work across six continents, most ecosystems, from oceans to deserts, and a broad range of species groups, from mammals to plants and insects. The guidance they present is based on consensus developed through work on the IUCN SSC Guidelines for Assessing Species’ Vulnerability to Climate Change.
According to the Introduction to the SSC Guidelines, changes have already been observed in a wide range of components of the Earth’s climate system, and ongoing changes are predicted, including in long-term climate patterns and trends, the magnitude and frequency of acute extreme weather events, and secondary impacts such as loss of sea ice and sea-level rise. Increases in atmospheric carbon dioxide concentration and ocean acidiication accompany them. These changes are having farreaching impacts on biodiversity, including at organismal, subpopulation, species and ecosystem levels. For some species, the net impacts have been positive, but for many more, the speed, magnitude and rate of change are having negative itness consequences for individuals which can lead to local or even global extinction of species. IPCC projections show that even under the most optimistic emissions scenarios, climate change impacts on biodiversity will be increasingly severe over the next century and beyond.
Climate change impacts may manifest directly, such as through the physiological stress experienced when ambient summer temperatures exceed organisms’ tolerances. Direct impacts typically include changes in behaviour, phenology and reproduction, and ultimately in survival of the organism and potentially its subpopulation and species. Other impacts occur indirectly through effects on interactions with other species including prey, predators, competitors, parasites or hosts, or on a species’ habitat, as well as through interactions with other threatening processes such as habitat loss. Humans’ reactions and responses to climate change (e.g., shifting agricultural areas, building dams and seawalls, migration) may also have marked impact ‘on species’ survival and capacity to adapt to climate change. It is likely that some mechanisms of climate change impacts on species are yet to be discovered.
According to the IUCN, climate change is one of the most pressing environment and development challenges confronting humanity today. Healthy ecosystems such as forests, oceans and wetlands make a critical and well-known contribution to climate change mitigation by absorbing and storing carbon. They also help vulnerable communities, especially those who depend on natural resources, to better adapt and become more resilient to the adverse effects of climate change. At the same time, they provide a number of other valuable economic, social and environmental beneits.
The Global Climate Action Summit (Sept. 13-14, 2018) and associated events provided a selfdescribed, “launchpad for deeper worldwide commitments and accelerated action from countries supported by all sectors of society - that can put the globe on track to prevent dangerous climate change and realise the historic Paris Agreement.”
An important naturebased solution for all levels of government, the private sector, civil society and international organisations, communities and others, offering the largest and most cost effective potential to mitigate climate change, is forest landscape restoration (FLR).
A frequent concern for both governments and companies that are considering adopting FLR as a climate solution is the cost. Saint-Laurent allayed such concerns by pointing to an evergrowing body of evidence on the economic benefits of FLR. Some of these benefits can be perceived in the short term, such as through jobs and income generated from ecotourism or nurseries, others in the medium term such as soil retention and improved productivity for farmers, and still others are long-term like the restoration of ecosystem services.