Extreme drought threatens Scottish habitats, say NatureScot

But as the weeks passed streams began to run dry, reservoir levels dropped and crops began to wither in the field and what had started out as a pleasant stretch of sunny weather began to take on serious implications, with fish stocks suffering and some parts of the Scotch Whisky industry having to temporarily halt production as water levels continued to fall.

As the unbroken sunshine continued it became evident that a succession of dry winters and higher than average temperatures, combined with low summer rainfall, had plunged the country into drought.

For those of a certain age it evoked memories of 1976, when tarmac melted and standpipes appeared in the street, and more recently that sizzling spell in 2003 when the 32.9C recorded at Greycrook in the Borders became Scotland’s highest ever official temperature

In a country renowned for its wet climate, the occasional hot, dry summer seems like little cause for concern, but that would be to underestimate the seriousness, because according to new research published by NatureScot the risk of extreme drought is set to rise rapidly within the next two decades as a result of climate change. 

Scotland’s nature agency has concluded that, instead of happening once every 20 years, incidence of drought could rise to one in three years, with dry spells potentially enduring for two to three months longer than in the past, and if that happens there could be serious implications for agriculture, wildlife and the environment.

At most risk says the agency is the east coast and the ‘hotspots’ of the Borders, Aberdeenshire, Caithness, Orkney and Shetland, but even though the west coast is set to remain wetter, it too will experience extreme drought.

Earlier this week, on World Wetlands Day (February 2), NatureScot revealed that many of Scotland’s wetland habitats, and the species they support, could be affected by this changing weather pattern. 

These ecosystems are adapted to continual or frequent high water levels and they play an important role in the landscape, filtering nutrients, slowing the flow of water and absorbing carbon.

Under frequent drought conditions these habitats would become stressed and may lose their ability to help regulate the environment.

The imminent nature of this threat may come as a surprise, but Francesca Osowska, NatureScot Chief Executive, says: “The findings of this innovative research are stark and demonstrate the urgency of the task before us if we are to ensure a nature-rich future for Scotland.”

And it is not just nature that is under threat, agriculture and people too will feel the effects of a drier climate.

From forestry plantations, to livestock production, cereal crops and seed potatoes, the impact on land use of prolonged water shortages, are complex and in Aberdeenshire and the Highlands, where 30,000 and 40,000 people respectively depend on wells, domestic water supplies could be affected by prolonged and frequent lowering of the water table. 

Extreme water shortages could also be felt in the Central Belt. Knowing what the threat is and where it is likely to felt most severely is essential if steps are to be taken to mitigate its effects.

Osowska says:“Enhancing and protecting nature is a key part of the solution to the climate emergency, and by identifying areas that may be at most risk we can focus conservation efforts to increase resilience and protect ecosystems.”

“At NatureScot we are already working to ensure that some of our most precious landscapes are more resilient to drought. Our Peatland ACTION project for example has put more than 25,000 hectares of peatland on the road to recovery since 2012 with funding provided by the Scottish Government.

“We will continue to focus on these kinds of nature-based solutions that are so essential in tackling the climate emergency facing us all and look forward to working with land managers, Scottish Water and SEPA in developing this work.”

The research was undertaken by Fairlie Kirkpatrick Baird, one of NatureScot’s graduate placement staff, who previously worked on peatland restoration and was interested in potential threats to Scotland’s important wetlands.

“When we think of extreme climate events in Scotland, we usually think of flooding and storms, but droughts are increasing here too. As in the drought over the summer of 2018, we are already seeing the negative impacts that can have on human and ecological environments.”

The standout finding of the research, says Fairlie, is not just that more droughts will occur, but the speed at which they are set to happen. 

“This study clearly shows that an increase in extreme droughts, with wide-ranging implications, is likely and not just in the distant future, but over the next 20 years or so and while that is concerning, it provides us with vital knowledge that can help us address the climate and biodiversity emergencies.

“By predicting which areas in Scotland may be most affected, we 
can start to take targeted mitigation action and try and reduce any potential damage.”

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Wetland sites throughout the country are at risk

The temperate rainforests of Scotland’s west coast are an internationally-recognised habitat, filled with rare species that thrive in the wet and mild conditions.

The bryophytes, lichens and other epiphytes that form a key part of this ecosystem are especially sensitive to dry conditions and can be damaged by even small decreases in water.

And they are not the only habitats that are at threat from drought. Many of the substantial number of designated wetland sites throughout the country occur in the eastern areas projected to be most at-risk. These includes Sites of Special Scientific Interest (SSSIs) on Orkney and Shetland, in Inverness-shire and in the Cairngorms, and Special Areas of Conservation (SACs) in the Borders, such as Whitlaw Moss and Branxholme. 

Increases in drought could also potentially have serious impact in the Flow Country, the 400,000 hectares of internationally important blanket bog covering much of Caithness and Sutherland that includes Caithness and Sutherland Peatlands SAC. 

When peatland dries out sections of it can crack or collapse, leaving it more vulnerable to the effects of heavy rain. Drier soil is also more likely to erode and the loss of plant growth could allow more nutrients to enter rivers and streams.

Not only that, but degraded peatland habitats risk losing their ability to sequester and store carbon, adding to climate change, and they hold less rainfall too, adding to more water entering the system and potentially causing flooding further downstream.

And when wetland areas shrink, the wildlife that relies on these habitats is under threat. Fairlie Kirkpatrick Baird says: “Huge numbers of dragonflies live in peat bogs and these need pools of water to reproduce.”

Meanwhile the breeding success of lapwing, redshank and snipe can suffer when surface water pools dry out, reducing the availability of invertebrates for their chicks, and frequent drought periods have been linked to population declines of great crested newts.

And as peatlands dry up, the types off vegetation they support also change, with sphagnum disappearing to be replaced by non-peat forming species, threatening the long term future of the habitat.

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Why restoring peatland is vital

Peatlands cover one fifth of Scotland’s land mass and they are one of the most effective ways of locking up carbon. However when peatland is degraded it releases carbon instead of storing it, which is one of the reasons why in 2012 NatureScot launched the Peatland ACTION project.

Since then it has helped to restore 25,000 hectares of damaged peat, working with landowners, volunteers, conservation bodies and Scotland’s national parks to safeguard this important habitat.

In Aberdeenshire, 1,500 hectares of peatland within the River Ugie catchment area have been restored and around Sandy Loch on Shetland, from where Scottish Water supplies 12,000 customers with drinking water, sphagnum has been replanted in order to stabilise the soil and prevent erosion.

A total of 70% of all Scotland’s drinking water is sourced from peatlands and where these are in good condition they assist with the filtration process, meaning that the water needs only minimal treatment. 

However because of historic drainage and burning, which was used to strip peat of its vegetation, as much as 600,000 hectares are in poor condition.

At Dryhope in the Borders the Peatland ACTION project has been working with the Phillipshaugh Estate to improve blanket bogs in the river Tweed catchment. 

Restoring the water-holding qualities of the peat to prevent flash flooding will reduce the risk of fish ova being swept away, which would cause a decline in salmon and trout within the Tweed and its tributaries.

On the Hope’s Estate in East Lothian, the project has helped to dam fast-running ditches in order to ‘rewet’ the peat and hold more moisture on the bog and similar measures are being carried out across 1,500 ha of peatbog in the Cairngorm, where erosion had been taking place.

This work is proving effective in restoring degraded peatlands and in 2020 the Scottish Government announced funding of £250 million over ten years for further restoration.

This article was brought to you in partnership with NatureScot as part of The Herald's Climate For Change campaign