You know you are in a special part of the country when you spot a herd of reindeer out on the hillside, or when a man sweeps past on his dog-sleigh. This is the Cairngorms, Britain's largest National Park. Up here in the Highlands of Scotland, the landscape is more like Greenland than Kent. The Cairngorms has more mountain birds, animals and plants than anywhere else in the country. It is at once the highest, wildest, coldest, snowiest, and some think the most dramatically beautiful part of Britain. And it is changing before our eyes.
For most of us, global warming hasn't affected the view from our windows. We see the same trees and wild flowers. The same birds visit the nut-feeder. Even the south coast doesn't yet look like Madeira. But if you doubt whether global warming has arrived in Britain, take a winter holiday in the Cairngorms.
For the Cairngorms are slowly, but increasingly surely, looking less and less like the Cairngorms. The area used to have our most alpine scenery, with snow-streaked mountain sides above the ancient pines and spring-green birch woods. But it has grown significantly warmer and wetter in recent years. In winter, rain is more likely than snow. Spring arrives a week earlier. The summers are slightly warmer and often a good deal drier. And autumn 2006 was virtually snowless.
In the end it's all about snow - and the average snow cover has decreased by a third. But even that kind of statistic disguises the fact that the snow is also melting faster. Alan Stewart runs Britain's only sled-dog adventure centre, based at a traditional Highland cottage not far from the local ski slopes. "We had just three days of continuous snow last year," he says. "There was a time when I could take the dogs out over the high tops to Ben Macdui and stay there for several days. You can't do that now. The snow melts too quickly. I have to take the dogs to the Alps to race them."
It is already too late for Alan to take visitors on sleigh rides, alpine-style. Instead, his dogs pull them along in a specially designed wheeled cart. Even that concession to the climate is getting problematical. "One minute it's cold enough, and the next it's too wet. The tracks rarely freeze up for long and soon flood with liquid mud. And on the occasions when it does snow, it's often violent and blocks the roads."
It's much the same story on Scotland's premier ski slopes. The 2003-04 season f was a disaster for the National Park's two ski companies. Every month from November 2003 until the following September had a mean temperature above the 1961-90 average. At the Glenshee Ski Centre near Braemar, downhill skiing was restricted to a short run on artificial snow. Having lost £1m in two years, the company was forced to sell its other centre at Glencoe, and by May it had gone bankrupt.
The larger Cairngorm Ski Centre, near Aviemore, has changed its name to Cairngorm Mountain Ltd to signify its switch from a winter attraction to an all-year one. The company has overcome a potentially fatal reliance on snow by building a controversial funicular railway conveying visitors up the mountain to Britain's highest café near the summit.
"The past 10 years certainly haven't been as good for us as they were in the Seventies and Eighties," says Bob Kinnaird, Cairngorm Mountain's chief executive. "It's becoming self-evident that providing skiing facilities in Scotland is increasingly difficult to sustain, and that any skiing area that has not been able to diversify will always have serious problems."
You can still get good snow for downhill skiing. Last winter was better than average at Cairngorm with a big January snowfall enabling most runs to stay open until mid-March. For a week or two there was better snow than at some alpine resorts. And a hard winter has been forecast for the coming months. But the predicted rise in the average temperature of the Cairngorms of perhaps 1.5 degrees centigrade by the mid-century will be more than enough to end any prospect of commercial skiing.
In fact, the Cairngorms of the near future may look less like mountains and more like unusually elevated moorland. A temperature rise of one degree is enough in effect to lower the height of the high tops by 200m. A two-degree rise will permanently reduce the amount of lying snow by up to 90 per cent. If the railways are still functioning by the mid-century you might be able to travel across the Highlands in midwinter from Edinburgh to Inverness and see no snow at all.
This is very bad news for the wildlife and scenery of the high tops; possibly the worst news since the last Ice Age. For one way or another nearly all the special species of the Cairngorms - the winter-white ptarmigan, the tundra-nesting dotterel and snow bunting, the alpine flowers and dwarf shrubs, even microbes and fungi living in the soil - depend on snow. And plenty of it.
This might seem unlikely. On the face of it, snow is a cold, useless substance. You can't eat it, you can't grow on it, and unless you are a polar bear, you can't live in it. Snow is more or less inert. But it works the landscape in subtle ways. In the windy, arctic conditions of the Cairngorms, snow blows around. It rarely remains long in a deep, even blanket. The wind sweeps it from the frosty ridges and piles it up in hollows or against cliffs. But far from acting as a deep freeze, the settled snow is a kind of thermal blanket, protecting the ground beneath and keeping it moist and relatively warm.
You can tell where the snow has lain even in high summer. Snow beds are marked by oases of moss and alpine plants. The lower ones are lush with blaeberry (the English bilberry), club mosses and other dwarf shrubs rooted in a thick carpet of moss. On the tops, the snow beds form crimson and green carpets of mosses and liverworts full of exquisite alpine species rarely seen in the Home Counties. They are also the home of "Britain's smallest tree", the "least willow", all of half an inch high; technically, these patches of thumbnail willows are miniature woods.
From the mossy snowbeds high in the hills, little rills fringed with saxifrages and other alpine flowers run between the boulders to join the burns far down in the glen. Without the snow providing a slow steady stream of meltwater fanning out down the hillside to sustain these high headwaters, an entire alpine habitat will be lost. It is the water from melting snow that sustains plant life in the gravelly cold desert of the Cairngorms plateau.
It is not only plants that depend on snow. Take that archetypal bird of the high tops, the snow bunting. This pretty white, black and brown-coloured bunting nests among the boulder fields near the mountain summits. To feed its chicks it needs a reliable supply of protein-rich insect food. But flying insects f can be in short supply up there in the wind and clouds. So where does it find them?
With the help of snow, says Professor Des Thompson, principal uplands advisor to Scottish Natural Heritage and an authority on upland birds. "Snow acts as a trap for flying insects. They are blown along by the wind and deposited on the sticky wet white surface, where, of course, they are very conspicuous. You can watch the snow buntings working the snow patches, picking off the stranded flies and returning to their nests with a beak full."
Another rich source of bird food is provided by the spring meltwater dripping from the edge of the snow. "As the snow retreats it triggers a big burst of life," says Professor Thompson. "Craneflies, whose larvae feed in the soil, emerge in vast numbers, as do other flying insects like midges and beetles." These natural larders are frequented by dotterel, wheatear, golden plover and other hill birds which need food at this time of year to feed their broods.
It is this synchronicity between nesting and insect emergence that has sustained the hill birds of the Cairngorms for thousands of years. But suddenly, says Professor Thompson, "the birds and their food may be going out of sync". The snow is melting earlier and faster. "The risk now is that the craneflies have responded by emerging earlier too, and by the time the birds are feeding their chicks the mass-emergence of insects will be over." The environmental fine-tuning that timed their brood to coincide with the greatest availability of food will break down.
The ptarmigan, whose plumage turns white in the winter, faces another problem. With no snow they are as conspicuous to a passing fox or eagle as a cue ball on a snooker table.
Professor Thompson compares the calamity that awaits the hill birds with a train crash. "The birds are being buffeted about: the snow isn't there where it used to be, the insects aren't emerging as expected, the whole hillside's not looking the way it used to. It might seem tranquil enough to us, but the birds are experiencing this huge dislocation in their lives. Nothing will be the same as it was."
There is the same sense of collision further down, in the upper edges of the pine forests where black grouse and capercaillie live. Both birds are already suffering serious declines. Overgrazing, deer fences (into which birds are wont to crash) and predation by resurgent numbers of foxes have pitched populations into something close to free-fall. The last straw may be the present run of wet springs.
According to Professor Thompson, the sequence of this train-crash may run as follows: in the increasingly wet springs, the hen bird spends more time with her chicks to keep them warm and dry. Spending longer with the brood instead of feeding means the mother loses condition. Losing condition means she is more likely to fly into a fence. Or get run over by a speeding 4x4. Or snapped up by a fox. Mother dies, the chicks starve. And there's another downward statistic in the gloomy record of the black grouse.
There are other knock-on effects of climate change that leave wildlife worse off. One of them is the rise of blood-sucking beasties like midges, horseflies and ticks. For the first time, walkers in the Cairngorms in summer are being advised to take midge repellent with them. Milder winters and wetter springs are being blamed for the sudden clouds of midges that were formerly associated with the boggier hills of the west. And since midges also bite deer, f they are driving the animals up the hill to spend longer on the high tops where they graze on sensitive alpine vegetation.
Ticks, which have always been present in relatively low numbers, have also increased. And they are active for longer. Stewart's sled dogs now catch ticks as late as November, whereas they used to be most bothersome in early summer. Despite their knack of finding embarrassing places to bite us, ticks are no joke. They can transmit Lyme Disease to humans. They also transmit the Louping-Ill virus to sheep and other domestic animals, as well as to grouse chicks. A bad infection of ticks can ruin the value of a grouse shoot. A scapegoat has been found in an animal that shares the same moors: the mountain hare. On some estates in the Cairngorms area there are reports of mass-shootings of mountain hare in a panicky attempt to preserve the grouse stocks. This is bad news not only for the hare. It will have knock-on effects on the golden eagle for whom this animal is an important source of food.
If ticks, disease and wet springs were not enough, heather-moor owners also face a drastic increase in the heather beetle. This tiny blackish beastie has an insatiable appetite for heather. Its grubs chew their way through shoots and leaves, stripping the plants back to the wood, leaving bare, brownish patches up to an acre in size. Whatever used to keep the heather beetle in check is clearly failing in its useful task. There have also been plagues of moth caterpillars causing the heather to lose water and go brown. It seems to be another case of nature out of sync - bugs that, with the help of climate change, have managed to turn the tables on their predators.
Given the threats to Cairngorm wildlife, the publication of a lavishly illustrated new book on the area is well timed. The Nature of the Cairngorms, a Scottish Natural Heritage (SNH) production edited by Philip Shaw and Des Thompson, celebrates the extraordinary wealth of wildlife found in the mountains, forests and glens of the National Park. The area boasts more than 1,300 rare species, more than any other similarly sized part of Britain. They include not only wild cats, eagles, ospreys and red squirrels but long lists of beetles, moths, lichens, mosses and fungi, many of them dignified only by a Latin name.
Indeed the full extent of the biodiversity of the Cairngorms has been uncovered relatively recently by roving bands of patient, dedicated specialists. Somehow we managed to miss a fungus the size of a horse's hoof projecting from the trunk of old aspen trees. And we thought a fungus called the devil's tooth - from its habit of sweating blood-red droplets - was very rare. In fact, it is quite common. Supposedly extinct mosses have turned up alive and well, in one case within yards of a nature reserve centre.
How much of this glorious diversity will be sucked under by climate change is anyone's guess. About the birds of the high tops, Professor Thompson is not optimistic. He predicts the extinction of the snow bunting as a breeding species by the end of the century. Other arctic birds, such as ptarmigan and dotterel, may survive, but in greatly reduced numbers. Any species that depends on snow - from the strange, iridescent slime-moulds that appear the moment the snow melts to an entire bestiary of arctic bugs - faces a doubtful future. "The speed of change is what is most alarming," says Professor Thompson. "In the mountains, which I like to think of as a sanctuary for wild nature, the reality may be ecological chaos and a widescale loss of species."
When it comes to plant life, Martin Gaywood, SNH's expert on climate change, says that survival may be a matter of dynamics. Do plants have the capacity to move up the hill at the same rate as their "climate space"? No one knows. Unfortunately, they face increased competition from more aggressive plants like bracken, broom and coarse grasses which are able to move in on the warming hillsides. A worst-case scenario cited in The Nature of the Cairngorms predicts the extinction of the entire alpine flora by the end of the century - an eco-catastrophe of the sort we have not witnessed in Britain for 10,000 years.
Is it really that bad? Not necessarily. With intelligent planning, Professor Thompson thinks the situation could be managed to minimise the worst effects on wildlife. While we may lose the snow bunting, other species, such as the black grouse, might be flung a lifeline. A reduction in numbers of those heavy grazers, red deer and hill sheep - something the National Park is able, in theory, to enforce - could see natural woodland regenerating on the slopes and sending tendrils of scrub up the burns almost as far as the plateau. And fewer deer and sheep on the tops should reduce the chances of delicate arctic vegetation becoming overwhelmed by grasses.
Against that will be the danger of wildfires in the predicted warmer, drier summers. The Cairngorms is among potentially the most combustible parts of Britain. Even in a globally warmed climate, the land will take time to recover from a hot fire. And bare, scorched soil and peat will erode quickly in the predicted stormy weather ahead. Fire control will become a major commitment, as it is already on the southern heaths of England.
Perhaps an optimistic scenario for the Cairngorms in a century's time would be as a kind of larger-scale, better-wooded North Pennines. Scots pine, birch and alpine willows will throng the slopes while the high tops will be grassier with patches of windblown heather, and perhaps the odd straggling, wind-bent bush. The hillsides will green earlier, and leaf-fall will be later. What there won't be is much snow. And without snow this will not be the Cairngorms many of us know and love.
If things do not go so well, the Cairngorms circa 2100 could be a mess. Let's be pessimistic for a moment and imagine burnt-out, eroded plains channelled with peat hags, woodland regeneration largely halted by deer and sheep that have grazed the alpine flowers from all but the most inaccessible crags. There would be precious little bird song and not a lot to attract the visitor. The view from the Ptarmigan Igloo restaurant, high on the slopes of Cairngorm Mountain, would be profoundly depressing.
The Cairngorms, then, has the potential to become the worst eco-catastrophe since the drainage of the English Fens, perhaps the worst since the Ice Age. It may happen slowly, so slowly that only those who return to watch the snow buntings in the spring or search for rare mosses by the alpine rills, will notice. Or it may happen suddenly, heralded by mass bankruptcy of the winter-holiday industry. All we know is that climate change has already started. Forget the theoretical models. Forget the Stern Report. Come to the Cairngorms and take a look. But don't forget the midge repellent. E
'The Nature of the Cairngorms' is available from www.nhbs.com or www.tsoshop.co.uk, price £20 plus p&p. Visit www.snh.org.uk for details about Scottish Natural Heritage. See www.sled-dogs.co.uk for details about Cairngorm Sled-Dog Adventure Centre