Snow patches in Scotland

Liz

On 7th October 2022, Iain Cameron, a UK snow patch expert, posted on Twitter: “So there we have it. It is confirmed that Scotland is snow-free yet again. The last patch, the Sphinx, disappeared sometime in the last 24 hours. The Sphinx has now vanished four times in the last six years, having done so only five times in the last 300 years.”

Iain Cameron and a team of volunteers have been exploring the Highlands for over 15 years, keeping an accurate record of snow patches across Scotland. The Scottish snow patch reports are published annually in the Royal Meteorological Society’s journal Weather, and have supported climate scientists in understanding how our changing climate impacts our landscape.

The annual snow patch reports have been published in Weather since 1997. These important climatological articles were first published by the late Dr Adam Watson, who started observing and recording snow patches in the Scottish Cairngorms around the late 1930s. Adam was a renowned ecologist, conservationist and mountaineer and meticulously recorded snow patches for many decades. In the 1970s, Adam developed a scientific method of snow-patch assessment and began a regular survey of the north-east Highlands. He would start surveying the mountains for snow patches each year from July onwards, repeating the study each month until the first significant snowfall, typically falling in October. Adam would record their size and mark their locations on a map.

These snow patch reports provide an important climatological record and are invaluable to scientists in measuring the impacts of climate change and monitoring these changes over many decades.

A snow patch is a partially compacted area of snow that is persistent for longer than the normal seasonal snow cover. Snow patches can either be seasonal, usually melting in late summer, or perennial, persisting for more than two years. Snow patches are typically found in sheltered spots where both the temperature and orographic conditions are favourable for the snow to survive.

Scotland’s longest-lasting snow patches are typically found in the highest parts of the Cairngorm Mountains and the vicinity of the highest mountain in the UK, Ben Nevis.

Some years the snow disappears completely in the Scottish mountains, as was the case in 2022. The first year recording the disappearance of all snow was in 1933. It was 26 years later, in 1959, before it happened again. However, in recent decades the frequency of years when Scotland’s snow patches completely disappear is accelerating, with snow-free years happening in 1996, 2003, 2006, 2017 and 2022.

Snow patches are often given names such as the Sphinx, named after the nearby climbing route located on the slopes of Braeriach in the Cairngorms National Park. The Sphinx is one of the UK’s most persistent snow patches, as it has only disappeared completely on nine occasions in the last 300 years. And 2022 is the fourth time in six years that the Sphinx has melted away completely. The increase in the disappearance rate is due to climate change and rising temperatures that increase the likelihood of snow-free years.

Snow is an important part of Earth’s ecosystem. The surface of our planet has around 18 million square miles covered in snow each winter. The white surface reflects sunlight, helping to cool the planet. As our climate warms the snow cover reduces and darker coloured land is exposed to the sunlight, absorbing the sunlight and causing the land to heat up more than it would if it were covered by snow. This amplifies the warming effect. We can model snow cover in future decades using climate projections and historical temperature, precipitation and snow cover data. A study published in 2019 highlighted a decline in snow cover in the Cairngorm Mountains between 1969 and 2005. The overall decline in snow cover is projected to continue and accelerate in the future.

To learn more about the Scottish snow patches and keep up-to-date with the latest research and advances in weather and climate, become a member of the Royal Meteorological Society, where among the many benefits you will have unlimited access to a portfolio of eight leading journals. See the inside front cover for details of a special offer for readers of The Geographer