It is renowned as the UK’s most “durable” snow patch – a covering that, most years, remains right through the summer months.

But, in the latest sign of climate change, the Sphinx in the Cairngorms has melted away. Experts believe it is only the eighth time this has happened in three centuries.

Each year, a number of patches can be expected to survive until the first falls of winter. The Sphinx is the most famous of them all. But the feature, which is located on remote Braeriach, has disappeared more frequently during the past 18 years.

Snow patch expert Iain Cameron said climate change was a likely factor. He added: “How ironic and prescient it is that our longest-lasting patch of snow melted for the third time in five years, right on the eve of COP26. Before 2000 it had melted only three times in the last 150 years.”

According to records, the Sphinx previously melted fully in 1933, 1959, 1996, 2003, 2006, 2017 and 2018. Before 1933, it is thought to have last melted completely in the 1700s. The Sphinx had shrunk to the size of an A4 piece of paper in recent weeks before finally disappearing in mild weather.

Mr Cameron, who is based in Stirling, has been studying snow patches in Scotland for 25 years and is author of the book The Vanishing Ice. He worked alongside the late Dr Adam Watson, a biologist dubbed Mr Cairngorms because of the many years he spent studying the mountains.

READ MORE: Dramatic pictures of Scotland's disappearing snow fields

Some of Dr Watson’s research on the Sphinx drew on information handed down by generations of people who worked and visited the area.

From the 1840s, the Scottish Mountaineering Club began noting the fortunes of the patch and, more recently, scientists and ecologists have also gathered data.

Mr Cameron said that, historically, the Sphinx was the UK’s “most durable” snow patch. But he warned: “That is being challenged because it is disappearing more often.”

Mr Cameron said warmer weather due to climate change “seemed to be the logical” explanation for the increased rate of melting. He added that the conditions were affecting snowy areas high on other Scottish mountains, including in the Ben Nevis range in Lochaber. Aonach Beag, near Ben Nevis, also has a patch of snow that has often survived from one winter to another. But Mr Cameron said: “What we are seeing from research are smaller and fewer patches of snow.” He added: “Less snow is falling now in winter than in the 1980s and even the 1990s.”

READ MORE: Cairngorms snow patch disappears in new global warming alert

Separately from Mr Cameron’s research, a report, commissioned by Cairngorms National Park Authority and published last year, said declining snow cover had been observed on Cairngorm mountain since the winter of 1983-84. Researchers also noted a trend for increasingly warmer weather since the 1960s, and suggested that, by the 2080s, there would be some years with very little or no snow at all on Cairngorm.

Lauren McCallum, of international climate change campaign group Protect Our Winters, said the Cairngorms – and the wider world – needed to be protected from further temperature rises. “We have to maintain a healthy temperature for our ecosystems and communities to survive,” she added.

The Sphinx lies in Garbh Choire Mor, a hollow known as a corrie that was formed by ice or a glacier during the last ice age. It is located on the 4,252ft-high Braeriach. Garbh Choire Mor is also described as Scotland’s snowiest corrie because of the amount of snow it can hold even through summer months.