Climate Change and Nature Blog Series No 3
by Colin Beale
Continuing our recent theme of climate change impacts on nature, this month we’ll turn to one of the most obvious impacts of climate change: changes in distributions – or where and how widely different species actually live in the UK.
As the climate changes we’ve seen how the timing of biological events change, and how climate change impacts population dynamics. Many of these changes are rather tricky to actually observe: you have to be paying very close attention to notice frogspawn arriving a few days earlier, or a change in birth rates.
As these changes accumulate, however, they can lead to distribution shifts. One example of this distribution shift is when climate change can make previously unsuitable places (where mortality rates were too high to sustain a population of a species) become more suitable. Subsequently, individuals dispersing beyond the usual breeding areas can establish new populations of a species in places that they were previously unknown. Around my hometown of York, for example, we’ve gained Nuthatches and Brown Argus butterflies in the last few years, species previously restricted to warmer parts of southern England. Indeed, because the UK is a fairly northern country, many species previously restricted to southern counties have been moving north, at an average rate of about 20 km per decade, and we’ve gained entirely new breeding bird species in these islands, like Black-winged Stilt and Glossy Ibis. All the colonisations are signs of wildlife successfully adapting to changing environmental conditions by shifting northwards.
The flip side of distribution shifts, however, are the losses: species like the Scotch Argus butterflies are restricted to the cool uplands and are retreating ever further up the mountains. With nowhere further north to go, such northern species as Dotterel, mountain ringlet and Iceland purslane are likely to be driven to extinction in the UK. This presents a conundrum for conservationists: in the UK these are very rare and highly threatened species, obvious priorities for conservation. However, if the species is common elsewhere where it is facing less of a threat from climate change, do we continue conservation actions in the UK, or do we prioritise scarce conservation funding on species with a better long-term chance of survival? And what about the Scotch Argus, which is actually a European priority species for which the UK has internationally important populations?
Further challenges for conservation arise from the observation that different species are showing different distribution changes in response to climate: some seem more sensitive to rainfall changes, others to temperature while others seem largely indifferent. This means that new communities of species are coming together that have no recent history of coexistence. We have little insight into how novel communities may function: could one species harbour a disease to which another is highly susceptible, for example, or will different upland plant communities be better or worse at storing carbon? Nor is the conservation community prepared to respond to wholesale community shifts: many conservationists still remain fixed on the mistaken (and unchristian) belief that our aim should be to restore some mythical pre-human or pre-industrial baseline.
Overall, and thanks to our northern location, the UK looks set to see more ‘winners’ than ‘losers’ from climate change-driven range shifts, but this is only thanks to our northern location. And it may be only short-lived. Although the current distribution changes we see are signs that many species are successfully adapting to changing climates, a key question is whether they can continue to move at a rate sufficient to keep up with ever increasing rates of climate change? This is surely easier for birds and insects than many plants.
Facilitating distribution shifts and welcoming novel communities provide interesting challenges for conservation today. Do you have views on how the conservation community, and A Rocha UK within it, should be responding? Do let us know via the comment function.
About the author: Colin is Reader in Ecology at the University of York, where he leads a group of researchers studying spatial patterns in ecology and conservation biology in the UK and globally. He previously worked for A Rocha Portugal and A Rocha Lebanon and is now a trustee of A Rocha UK. As a member of his local parish church, Colin also advises the Diocese of York on environmental matters.
This blog was written for A Rocha UK’s Wild Christian email, April 2021. Sign up here to receive future Wild Christian emails