Guest blog by Dr Mike Morecroft, Principal Specialist, Climate Change at Natural England
This year’s State of UK's Birds report has a special feature on climate change. Why climate change? Put simply, because climate change presents one of the biggest threats to birds and other wildlife and there are things we need to do to reduce that threat and even help some species take advantage of new opportunities. Those of us who work for conservation organisations have a particular responsibility to take a lead in responding to climate change. But let’s look at that this in a bit more detail.
Climate change is real.
The most recent assessment report of the Intergovernmental Panel on Climate Change, published in 2013, concluded that ‘warming of the climate system is unequivocal’ and ‘it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century’. It’s worth reflecting on how much clearer the evidence is now than it was in 1990 when the IPCC published its first major report (and I was a PhD student studying mountain plants!). At the time they could only say that the observed warming at the time was ‘broadly consistent with predictions of climate models, but it is also of the same magnitude as natural climate variability’. A lot has changed since then. Here in the UK, average temperatures have risen by nearly a degree compared to the 1980s. We’ve also seen a trend towards proportionately more rainfall falling in heavy storms and the sea level is rising by about 3mm per year.
But what does it mean for our wildlife?
One of the most rewarding things I’ve done in the last few years has been to chair a group of over 40 scientists reviewing the impacts of climate change on the biodiversity of the UK (Morecroft and Speakman, 2015.) We found plenty of evidence that nature is changing. One of the clearest signs is that species are moving northwards, colonising new places as they become warmer. There are some good examples amongst the birds, for example Dartford warblers have spread far beyond the sites in the far south where they previously just had a toe hold in the UK. Of course that’s good news, but the flip side is that species at the southern limits of their range are struggling and we are starting to see declines in northern species, such as the Mountain Ringlet butterfly. And those species that increase in the UK may well decline further south.
Photo: Some species are moving northwards, colonising new places as they become warmer, Dartford warblers is a good example as they have spread in the south where they previously just had a toe hold in the UK. Photo by Ben Hall (rspb-images.com)
As well as species changing their distribution we are seeing other changes, for example seasonal life cycle events, such as egg laying and budburst of trees are becoming earlier – by nearly two weeks on average. Most of us are cheered by the signs of spring, but there can be problems where different species are affected to different extents. A bird that hatches before it’s insect food species have emerged will face problems, as will a plant that flowers before its pollinator emerges.
Perhaps even more important than the effects of temperature are those of changes in rainfall and sea level. The best climate models show that we can expect more variation in rainfall and proportionately more rain falling in winter, with less in summer. This leads to an increasing risk of both floods and droughts. Whilst some species thrive in a hot dry summer, others suffer and this includes some of our forest tree species, such as beech trees, which have relatively shallow roots. During the 1976 drought there was widespread tree death and a sequence of similar events would change our woodland landscape with consequences for the many species that depend on it. At the coast, rising sea level leads to increased rates of erosion and loss of land area. This is a problem for the people who live there and can also be a problem for natural habitats like salt marsh, especially if they are ‘squeezed’ up against hard flood defences.
So what can we do?
Quite a lot. The situation is by no means hopeless, but we need to act quickly.
First of all, reducing greenhouse gas emissions is essential. It will take time, but it is starting to happen. Conservationists can play their part, not just by our personal decisions (yes, I do have solar panels on my roof) but also by restoring ecosystems like peatlands to reduce emissions. Natural habitats, particularly woodlands, can also help to remove carbon from the atmosphere through photosynthesis.
Nevertheless, the climate is already changing and will continue to do so for some decades under even the most optimistic scenarios for cutting emissions. Adaptation is therefore essential if we are to give our wildlife the best chance in future. Species have an innate capacity to adapt to change and to survive adverse conditions but this resilience is compromised in Britain today by a range of other pressures. By improving our natural environment we can help to rebuild resilience. We know for example that larger wildlife sites in better condition are more likely to allow species to survive an extreme event such as a drought. Larger protected areas also improve the chances that there will be local areas, refugia, where the microclimate is a little cooler, for example on north facing slopes, giving species a better chance of survival.
Photo: Managed realignment projects, such as the RSPB Wallasea Island allow new coastal habitats to form as old ones are lost to the sea. Photo by Andy Hay (rspb-images.com)
Adaptation is not just about building resilience. We also have to recognise where change is inevitable and manage for the best outcome. Those species which can expand their range with climate change, will only be able to do so if there is suitable habitat and any necessary protection. At the coast, managed realignment projects, such as the RSPB’s reserve at Wallasea Island allow new coastal habitats to form as old ones are lost to the sea. Reviewing the need for climate change adaptation is now a standard part of site management planning on our Natural England NNRs.
If you are interested in finding out more about how conservation can adapt to climate change, take a look at the Climate Change Adaptation Manual, published by Natural England and the RSPB http://publications.naturalengland.org.uk/publication/5629923804839936