28th July, 2020
This report details research findings on the historical changes in snow depth and number of days of snow on Cairngorm Mountain and how snow may respond under climate change. It is an extension to the report ‘Snow Cover and Climate Change in the Cairngorms National Park: Summary Assessment’ produced by ClimateXChange in 2019.
Key Findings: Observed changes
- There has been a decrease in the observed maximum and average snow depth since the beginning of records (1983-84 winter). Maximum snow depth has declined by c. 10cm and the average by c. 3cm.
- There has been an observed decrease in the number of days when snow depth exceeds specific amounts. The largest decreases have occurred for shallower depths (>2<5, >5<10 cm) of c. 10 days since 1983.
- The mean snow depth per month has decreased in January and February since 1983. Depth per month has been highly variable but the observed trend has been downwards. Other months have different trends: March has had a slight decrease whilst November has been consistent and December a slight increase.
- For all months there is a clear increasing warming trend in observed maximum and minimum temperature between 1960 and 2019. The largest increases have occurred in April. The main snow fall months of January and February have had a relatively small increase in temperature.
- There has been an increasing trend of mean monthly precipitation amount for November, December and January since 1960, whilst March’s amount has decreased.
- There has been an increase in mean monthly solar radiation (MJ m2 day-1) in February, March and April since 1994, implying greater heat energy input at the ground surface.
Key Findings: Future projections
- Likely to be a decline in snow cover days per year from the 2030s for Aviemore, the Cairngorm Chairlift meteorological station and Ptarmigan Restaurant on Cairngorm Mountain. This trend will continue through to the 2080s.
- There will be large variation between years and there are likely to still be some years comparable with past amounts of snow cover, but these will be less frequent.
- These findings are in line with results from the UK Meteorological Office and Inter-governmental Panel on Climate Change.
- Temperatures are projected to continue increasing, with a higher probability of having more days when the temperature is above a threshold of 2°C for snow formation.
- There is an increasing probability of more heat energy input on ground surfaces with an increasing snow melting affect.
- Snow is complex to model and project in the future, especially in temperate regions like Scotland with its strong maritime (Atlantic Ocean) climatic influence. Changes in seasonal variability will depend on how air flow over the UK (e.g. location of the jet stream) is affected by global scale ocean-atmosphere circulation processes. Our findings are a good indicator of future trends, but there remain substantial uncertainties at Cairngorm Mountain that need to be considered in making this a more detailed assessment of future snow cover.
Warming will continue meaning snow cover and depth is likely to decrease on Cairngorm Mountain from the 2030s. There are likely to be some years with snow comparable to the past but overall there will likely be a decrease.