A little Egret flies over the Campsie Hills vineyard.
At the Royal Botanic Garden in Edinburgh, Geoffrey Harper hesitates by a Chinese witch hazel, its frizzy yellow catkins brightening a grey winter morning. Normally the shrub flowers between December and February; in the botanic garden, these raggedy little blooms first started opening on 5 October.
"We have a number of shrubs like this which used to be spring flowering but which are now winter or even autumn flowering," remarks Professor Harper, as a grey squirrel prances among these premature signals of spring. A long-time volunteer at the RBGE, he walks the garden most days of the year, checking 100 different plant species, as part of the garden’s Edinburgh Phenology Project, charting their flowering times as indicators of seasonal shift.
The popular imagination can hardly be blamed for swithering between imminent ice age or global warming; but consistently rising temperatures, the increasing early flowering of plants, the arrival of exotic bird species and a worrying increase in river flow and water levels are the indicators being taken very seriously indeed by scientists.
Back at the Botanic Garden, Harper points to a scattering of emerging snowdrops and bright yellow clumps of aconite: "Most of the spring bulbs are also very responsive to temperature. We have results for three years now and in every case they’re flowering earlier each year. It may be just a fluke, but it’s good anecdotal information in suggesting that something’s happening."
Something is indeed happening. The RBGE has one of the longest records of flowering of any botanical garden in the world, going back to records kept in the 1850s. As Harper patrols the garden, Professor Roy Thompson, of Edinburgh University’s School of Geosciences, was in Australia, analysing the flowering data from the RBGE with Professor Malcolm Clark of Monash University, Melbourne. Thompson and Clark predict that by the end of the century, all the fruit trees, bulbs, garden flowers and shrubs involved in the study will be flowering as much as 50 days earlier. "Temperature-sensitive plants will modify their behaviour in many parts of the world as climate warming sets in," says Thompson, "but the largest changes in flowering times and plant development will occur in these parts of the world with oceanic climates - that is in climates exactly like Scotland’s."
While such a prospect may be welcomed by fruit-growers, a milder climate may increase the risk of disease among the plants, while late frosts could damage flowers that are too far ahead of their season. We may savour the idea of warmer summers; however, the reality may be rising sea levels, increased winter flooding, and unmanageable insurance bills, against a global backdrop of a million lost species by 2050 and the appalling social impact of widespread drought, flooding and famine.
Meanwhile, the climate changes threatening some upland species are already having their effect on Scotland’s ski industry, with Glenshee Chairlift Company, which owns Glencoe and Glenshee resorts, putting them on the market, following losses of £1 million over the past two years, due to lack of snow. Earlier this week, Adam Watson of the Centre for Ecology and Hydrology in Banchory, Aberdeenshire, suggested that the industry may have no more than 20 years left.
There are some consolations however. Earlier this month Dr Gregory Jones, a climatologist at Southern Oregon University with an interest in viniculture, speculated that Scotland might well be able to support vineyards, most probably for white wines, within the current century. By 2050, he said, Mediterranean classics including Chianti, Rioja and Cava will no longer be able to grow in the soon-to-turn arid ground of Italy and Spain, driving vineyards to higher ground. Scotland, with its increase in temperature, will be able to accommodate them.
Less appealing will be an extension of the midge season - something that is already happening, with midges occurring in October.
A vocal few remain unconvinced. Harvard astrophysicists Willie Soon and Sallie Baliunas, for example, argue that current rates of global warming were matched and possibly even exceeded during the Middle Ages. But Dr David Viner of the Climatic Research Unit at the University of East Anglia says: "OK, we had a cold snap and temperatures dropped in Scotland, I think, about minus five or minus six, and that was associated with a very cold wind, but we don’t have to go back very far, to the late 1970s early 1980s when we were getting minus 20, minus 25. It shows how much the climate has changed, if a short and not really cold snap is seen as unusual."
At the Stirling headquarters of the Scottish Environment Protection Agency, Dr James Curran is blunt: "We’re convinced [climate change] is the greatest environmental threat facing all of us. The UK is one of the leading nations in the world for undertaking this kind of computer modelling and all the evidence we’ve looked at convinces us it’s a man-made effect and it’s with us already."
So far as Scotland is concerned, says Curran, current predictions are for our temperatures to increase by between 2.5 and 3ºC by 2080. "But because the temperature increases, the atmosphere will be warmer and holding more water vapour, so you can expect more energetic storms, and more and heavier rainfall, particularly given our location, with storms coming in off the Atlantic. All the evidence we have is for an upward trend in rainfall and river flow across Scotland over about the last 50 years, with average increases in flow of 20-30 per cent not unusual."
That anecdotal evidence is backed by rainfall records, with rivers flowing higher in the wetter winters. So far as summers are concerned, he adds, "if anything, the evidence is that they are going to get drier and all of that fits in with climate change predictions from global models."
By 2080, Curran goes on, Scotland could be looking at increases in winter rainfall of up to 30 per cent, while in summer, particularly in the east, we might be seeing a 20 per cent reduction in rain. "It’s a double whammy - we’re maybe going to get possibly three times more flooding of rivers than at present, but also more droughts. And we’ve got to start preparing for that."
That’s just the rivers. Curran believes we could experience something like a 50cm rise in average sea level by 2080 - nothing to do with melting Polar ice caps, but because seas, globally, are warming and expanding. "Even if emissions were drastically reduced today, these levels will continue to rise for many centuries to come, perhaps to around 0.7 metres in 600 years, but under a much more realistic scenario of continuing emissions and continued global and oceanic warming, the expected sea level rise around Scotland will be around 50cm by 2080. We reckon that by 2080 there could be up to ten times more coastal flooding than we have now.
"And the other downer," he grins wryly, "is a predicted increase in storminess and wind speed, perhaps only 3 to 4 per cent, which doesn’t sound very much, but figures produced by insurance companies show that a 3 per cent increase in wind speed means a 30 per cent increase in damage."
But while we humans try to cope with changing climatic conditions, what of Scotland’s other inhabitants? Organisations such as Scottish Natural Heritage and the RSPB are particularly concerned at the effect of climate change on montane species such as the mountain hare and the dotterel, snow bunting and ptarmigan, which will find themselves forced northwards and their range reduced by rising temperatures. Saxifrages, trailing azalea and moss campion are among the plants threatened. "We’re talking now about decades, rather than centuries," stresses SNH’s strategic science adviser, Dr Noranne Ellis. "We are very concerned: we’re likely to see these species disappearing from Scotland within this century."
Northern species whose "climate space" will be reduced include the red-throated diver and the Scottish primrose, while there are fears for the Scottish crossbill, the only bird unique to the United Kingdom and also liable to be the only bird in the UK liable to become extinct, as the only suitable environment it could move to as temperatures rise would be Iceland, which is almost certainly too far away for it to migrate.
Conversely, rising temperatures have seen an increasing number of exotic arrivals. It shouldn’t be too long before the avocet is breeding here; another wader, the little egret, once a vagrant visitor to England from the Continent, is now breeding there and is seen north of the Border, while the nuthatch, already spotted in Edinburgh, is expected to become a familiar sight. Less appealing will be an extension of the midge season as a result of warmer, damper summers.
However, all these predictions presuppose rises in temperature. There remains an even more alarming scenario - that within just decades, Scotland could find itself plunged into a "mini ice age". Researchers from the government’s Marine Laboratory in Aberdeen, along with Norwegian and Faroese colleagues, are monitoring the apparent slowing of the circulating currents in the north Atlantic which bring us the North Atlantic drift, or "Gulf Stream", which gives us more temperate climes compared to other areas at similar latitudes.
There are fears that with north Asia and the Arctic warming, greatly increased input of fresh water into the oceans from north-Asian rivers will interfere with the system of circulating currents which ultimately powers the North Atlantic Drift. Without it, our climate could very quickly become Siberian.
• The UK Phenology network encourages the public to note flowerings and other seasonal changes at
www.phenology.org.uk