Long-term observations of increasing snow cover in the western Cairngorms

The authors used photographs collected as part of the ECN monitoring at our Cairngorm site to determine how the duration of snow cover has changed in recent years.

Reference

Andrews, C., Ives, S., and Dick, J. 2016. Long-term observations of increasing snow cover in the western Cairngorms.  Weather 71(7):178-181. DOI 10.1002/wea.2731

Abstract

As part of the UK Environmental Change Network (ECN) long-term monitoring, an automatic repeat-photography camera was installed to record changes in landscape phenology in the Allt a'Mharcaidh catchment, Cairngorms National Park, Scotland. For 13 consecutive winters between 2002 and 2015, the date for the onset of continuous winter snow cover, and subsequent melt, was recorded on slopes of north and north-easterly aspect at altitudes between 450m and 1111m amsl. Results show that the period of time during which snow is continuously present in the catchment has increased significantly by 81 (±21.01) days over the 13-year period, and that this is largely driven by a significantly later melt date, rather than earlier onset of winter snow cover.

Why this research matters

This paper is relevant to the following issues:

• Climate change
• Tourism and the local economy
• Flood risk
• Water regulation

In brief

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In more detail

The duration of snow cover in mountain regions such as the highlands of Scotland is important from both ecological and socio-economic perspectives. For example, it determines the length of the plant growing season and influences large-scale water regulation (e.g. flooding risks), as well as being crucial for snow sports and wider winter tourism.

Changes in the duration of snow cover could, therefore, affect both the ecology and the economy of upland areas.

The Cairngorms National Park in Scotland supports one of the UK’s largest winter sports economies. Whilst the National Park Authority aims to promote sustainable outdoor recreation in the Park and support the local tourism industry, the potential for climate change to impact winter visitor numbers is acknowledged.

At the ECN Cairngorms site, daily and weekly photographs are collected as part of the ECN monitoring programme. The authors of this paper used these images to determine the number of days snow was present in the upper Allt a’Mharcaidh catchment for each winter between 2002 and 2015.

The period of time that snow was present was found to vary between a minimum of 157 days in 2002/2003 and a maximum of 260 days in 2012/2013. Although variable from year to year, the period of time that snow was present was found to have increased significantly over the 13 year period, mainly as a result of melting later in the spring/summer.

This increasing period of persisting snow appears to be primarily driven by small changes in the mean winter/spring temperature, with modest decreases in temperature resulting in longer periods of snow cover.

The reported increase in the duration of snow cover in the Cairngorms may be good news for the local winter recreation economy. However, despite the clear trend for increasing snow presence over the past 13 winters, it would seem unlikely that this increase in snow presence will continue in the long-term.  With high elevation snow cover models predicting reductions in snow cover under all climate scenarios, it is likely this trend will be reversed in the near future.