Scottish Sphinx snow patch reveals warming climate

It has been revealed that the Sphinx - which is a patch of snow believed to be the longest-lasting in the UK - has now melted for four years on the trot. Citizen scientist, author, and keen walker Iain Cameron - who incidentally also works in the Scotch Whisky industry, ticking another stereotype box! - has spent decades surveying the patch, which is hidden in one of the most isolated parts of the Scottish Highlands…

Iain - Sphinx is a patch of snow. It got its name from a rock climb. Two climbers in the 1940s were pioneering some climbs in remote parts of the Scottish Highlands. The patch lies directly below it. And so there's no real mystery to the name, there's no esoteric similarity between this patch of snow and this Sphinx in Egypt. It's purely because the climb above it was so-called. But it is the most enduring, if you like, patch of snow in all the British Isles. It has been monitored closely since probably the mid 1800s. But there's good anecdotal evidence going back to the 1700s and even beyond

Chris - How big is it?

Iain - Reasonably. So it depends when you go, because it does all depend on winter snow. So if you go there in a snowy year it can be as much as 30, 40, 50 metres even. But some years you go at the end of September, the start of October, it can be a little larger than a dinner plate. And that was the case this year. So it really depends.

Chris - And what got you interested?

Iain - I've been interested in patches of snow since I was a lad, literally a lad nine years old. When I gazed from the bedroom of my parents house that they still live in to this day, in fact. Through onto Scotland's most southern Munro. A Munro is a hill above 3000 feet. And on the southern flank of this hill, there was a large patch of snow, and this was in May. And I found this very curious because all the snow around had melted ages ago. As far as I was concerned. All the snow that I used to go out and play in as a young lad. Here I was looking at this large patch of snow, it looked like a medallion hanging around the neck of this hill. And it just flipped a switch in me. It just triggered an interest, which is endured to this day.

Chris - And how do we know that this patch that we dubbed the Sphinx is genuinely the longest lasting? And there must be other bits because I remember being at the top of Ben Nevis, I was sort of navigating my way through dense fog <laugh>, and I was looking at bits of snow at the top of Ben Nevis. So presumably this is not an isolated example.

Iain - No, it's not. You're right. Ben Nevis is another hill which contains long lasting patches of snow. And in fact Ben Nevis is probably one of the most reliable places to see long lying snow. However, because Scotland is a reasonably small place and the areas of upland that exceed 4,000 feet or 1,220 metres, there aren't that many. And they're quite busy on these hills and they have been for quite a while. So there are quite a lot of people out there and quite a lot of people observing. And so we know that the Sphinx is the longest lasting just because there are very good records going back, you know, well over a hundred years.

Chris - And what's the problem with it?

Iain - It's melting more often than it used to. So it persisted from the 1700s all the way through unmelted. And in 1933 it melted the first time this was a big deal and members of the Scottish Mountaineer Club thought it needed to be recorded. So they wrote The Times and The Times published a letter from there. It was quite closely observed until it melted again in 1959, so 26 years later. Okay, not a biggie, you might think. 1996 was the next time it melted. So there was a third time now in the 20th century. You couldn't say it was a regular occurrence at melting, but it melted again. But then after 1996, things started to change. And it melted again in 2003, 2006, 2017, 2018, 2021, 22, 23, 24. So it's now melted in four consecutive years. So it used to be an isolated incident of it melting. It is now an isolated incident of it surviving. So there's a complete 180 flip.

Chris - Have we got an explanation as to why it's melting? I'm not being facetious, obviously ice melts when the temperature rises, but can we attach this to any kind of particular change in climatic conditions, winds? Is there any particular factor that's doing this or is it just that we think average temperatures are rising year on year and it's intensified the frequency of melting.

Iain - The most important factor for a patch of snow surviving from one year to the other is not summer temperature, but is in fact the amount of snow that falls in winter. So if for example, you have got 20 metres of depth up in an average season, then it's going to take summer a lot less time to get through 20 metres than it is to get through 30 metres of depth. The reason why not as much snow is falling is because the precipitation that used to fall as snow is now falling as sleet or rain at high level. And even the difference of a degree or so in temperature can affect drastically the amount of snow that falls at these locations.

Chris - Indeed, researchers pointed out, I think just this week, that we assume with climate change we're going to see a warming that's going to be evenly spread across the year and across the seasons. But in fact it's not like that. We don't see warmer summers and warmer winters. We may see an asymmetry with the winters getting a lot warmer, but the summer's not much warmer and that could have quite dramatic shifts in the way the weather works.

Iain - Yeah, that's right. I'm hopeful that this period is anomalous and we will go back to a period where Sphinx and others like it survive from one year to the next. I am fearful, but as long as I'm able to, as long as I've strength in my legs, I will keep going back because for me it's a little pilgrimage going to these places and one which I enjoy thoroughly. Not only to see the snow itself, but just to be in the wildest places that Scotland has to offer is a real joy.