Guest post from Rachel Warren, Reader in Integrated Assessment of Climate Change, Tyndall Centre for Climate Change Research, University of East Anglia
We have just published the first global scale analysis of impacts of climate change on the climatic ranges of 50,000 widespread and common animal and plant species in Nature Climate Change. The main finding is that if no action is taken to reduce the emissions of greenhouse gases that cause climate change, over half the plants (57±6% ) and one third of the animals (34±7% ) that we studied would lose more than half their climatic range by the 2080s.
The climatic range is the area of land on the earth’s surface that has a climate suitable to live in. The area in which a species actually lives, its geographic range, isn’t necessarily the same because there will be many habitats within the climatically suitable range, some of which might not be suitable, and humans will have modified the landscape, making some other areas also unsuitable. But if climatic ranges are reduced so much, many common and widespread species will disappear from many of the places where they are currently found.
Many other species of plants and animals for which we had no data will also be affected. These range losses are not offset by the small percentage of species projected to gain more than 50% of their climatic range (4% of the animals and none of the plants).
Proportion of species losing 50% or more of their range by the 2080s under different emissions scenarios: Red = SRES A1B; Green = emissions peak 2030; Blue= emissions peak 2016
If there’s no action to reduce the emissions of greenhouse gases that cause climate change, it’s quite likely that global temperatures could rise by 4°C, relative to pre-industrial times by 2100. If emissions were reduced rapidly and promptly, temperature rise by 2100 could be limited to 2°C above pre-industrial levels, and would then stop rising. This would reduce the range losses by 60% if emissions peak in 2016 or by 40% if emissions peak in 2030.
It’s harder to avoid so many of the range losses if emissions don’t peak until 2030. The fastest rate that economists think emissions could be reduced is about 5% annually, and if emissions don’t peak until 2030, even if you reduce emissions at 5% annually, you can’t get that 60% avoidance of range loss that you can get if emissions peak in 2016.
Reducing emissions reduces the amount of climate change, so that species lose less of their ranges. Also, it slows climate change down, so that biodiversity has up to four more decades of time to adapt to the same amount of change in temperatures and rainfall patterns.
Without emission reductions, the climate becomes particularly unsuitable for plants and animals in sub-Saharan Africa, Central America, Amazonia, Australia, North Africa, Central Asia, and south-eastern Europe. Biodiversity losses are reduced worldwide if emissions are reduced, and the benefits are highest in these regions.
Our study takes in account the ability of species to adapt to climate change by moving, by using observed rates of movement of species that are already responding to climate change. Plants, amphibians and reptiles are more sensitive to climate change than birds or mammals, due to their lower ability to move. Amphibians are most at risk with 50±7% of species losing over 50% of their climatic range by the 2080s. Examples of animals projected to lose more than half their range include lion, meerkat, harlequin frog and Tokay gecko; whilst examples of plants include cacao, coffee, teak and pineapple.
Many other studies have looked at the effects of climate change on species, but have tended to focus on species with small ranges that are likely to go extinct as a result of climate change, or have looked at single regions of the world. Until now, little was known about how much reducing greenhouse gas emissions could reduce the impacts of climate change on biodiversity, particularly for common and widespread species.
Even small declines in common and widespread species can significantly disrupt functions that ecosystems perform for humans. These are things like nutrient cycling, air and water purification, flood prevention and control, conservation of soil and erosion prevention, provisioning of food and fuel, pollination, recreation, and ecotourism. The large range losses in many species that we found in the study imply a substantial loss of these ecosystem services, which are important to agriculture and to human health and wellbeing by the end of this century. Prompt and stringent reduction of greenhouse gas emissions would substantially reduce range losses and preserve these services that the biodiversity provides.
Actual species declines might be larger due to habitat loss due to land use change, man-made barriers to species movement (eg roads, intensively farmed areas), and complex scientific issues which could not be included in our study, such as interactions between species, and the effects of floods, droughts, pests and diseases, all of which are themselves affected by climate change.
In this study I enjoyed collaborating with a great team of people, including Dr. Jeff Price at the Tyndall Centre, UEA where I also work, and with Dr. Jeremy Vanderwal at James Cook University, in Australia. We used data from the Global Biodiversity Information Facility (GBIF) for the 50000 species.