How is climate change affecting nature?

Climate change presents one of the largest threats to birds and other wildlife. But as our understanding of the species struggling from climatic changes increases, so too does our toolkit for identifying solutions. As COP26 draws to a close, today's blog highlights the latest research from our team of scientists, working on understanding the impacts of climate change.

Upland species

Amongst the species most likely to be detrimentally impacted by climate change are those that inhabit mountainous areas. Faced with a changing climate, the general expectation is that species will move their ranges to higher latitudes or altitudes, tracking suitable climatic conditions. But, specialists of mountain environments often do not have that option, as they already occur at the highest altitudes, and thus cannot move to higher altitudes to track favourable climatic conditions.

RSPB is conducting research to better understand the impacts of climate change of some of the UK’s specialist mountain species. For example, the dotterel is one of only very few truly montane-breeding bird species in the UK, and RSPB research has found that that this species has declined by 57% in Britain since the late 1980s, with its distribution also having shifted uphill by 50m. As yet, however, we have been unable to identify any specific mechanism through which climate change has adversely affected dotterel.

A male dotterel on a nest at around 850m in the Drumochter hills © Steven Ewing

Mountain butterfly

Another mountain species that RSPB has invested research effort in is the mountain ringlet, the UK’s only montane butterfly, restricted to parts of the Lake District and central Highlands of Scotland.

Like the Dotterel, research by the University of York has shown that the distribution of Mountain Ringlet has shifted to higher elevations in recent decades due to the disproportion loss of low-lying colonies. RSPB research has provided for the first time detailed information on this species habitat preferences as a requisite basis for then developing a more mechanistic understanding of climate change impacts.

Female mountain ringlets, like this specimen, are more sedentary than the males (c) Steven Ewing

Furthermore, a particularly potent impact of climate change on mountain species is influencing the occurrence and duration of snow cover, and we are also working with academics at the University of Edinburgh to retrospectively model long-term changes in snow cover at Scottish montane sites to understand potential biological impacts on a range of montane specialists.

In our oceans

We know much about how climate change is impacting wildlife and ecosystems. Many of the best-studied examples come from terrestrial systems, but some of the earliest and most dramatic impacts are happening in our oceans. Sea temperatures, salinity, water density and acidity are all changing.

Species are moving towards the poles, plankton is blooming earlier, coral reefs are bleaching and dissolving, and fish communities are changing. And of course, the charismatic and important seabirds and sea mammals at the top of the food chain are also affected.

Kittiwakes

Research shows that changes within our oceans, driven by our changing climate, are linked to breeding failure and declines in some of the UK's seabird colonies. For example, kittiwakes have experienced population declines of 29% across the UK over the last two decades and RSPB-led research shows climate change is making it harder for them to raise chicks.

Work led by Dr Matthew Carroll used a unique multi-colony tracking dataset to identify the foraging areas used by eleven kittiwake colonies throughout the UK and Ireland. This research looked at three key oceanographic variables (sea surface temperature, stratification strength, stratification onset) and found that higher productivity was associated with lower sea surface temperature, and weaker, later stratification.

Kittiwakes have been shown to be susceptible to climate change (c) Paul Turner (rspb-images.com)

By quantifying this relationship, the authors were able to predict what would happen to kittiwake productivity in response to future climate change. Climate change projections indicated that rising sea surface temperatures could drive further declines in kittiwake productivity by up to 43% by the late 21st Century. Rather than climate change directly affecting the birds, indirect mechanisms, through changing oceanographic conditions affecting their food supply, were thought to be the key threat.

Impact on colonies

Recently published work led by Dr Ian Cleasby, in partnership with colleagues at BTO, has investigated climate-projected changes in the at-sea distribution of seven seabird species breeding in Western Scotland and Northern Ireland. Seabird distributions were primarily influenced by predicted changes in the relative size of different breeding colonies due to shifts in their demography in response to climate change.

The work predicted declines in the number of kittiwakes, guillemots, razorbills, sandwich and Arctic terns across the region. In contrast, shag and common tern populations were projected to increase.

Climate change is unlikely to have a uniform impact across seabird colonies and this could alter UK-wide seabird distributions as some colonies grow, or remain stable, while others decline. Birds may also have to adjust their foraging behaviour, targeting new areas or ranging further afield.

This needs to be considered carefully when we are managing the marine environment, whether through marine protected areas, effective spatial planning or measures to sustainably manage and conserve forage fish populations. Such measures are an essential part of the conservation toolkit to improve the resilience of our seabird populations to climate change.

Continue reading

• Rare breeding birds and climate change
• A trio of climate change papers hit the press
• The heat is on - how bird populations respond to climate warming

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