FROM dreich to drought in just 70 years. The most detailed-ever study of predicted rainfall and temperatures in Scotland has revealed precisely where climate change is likely to hit hardest.
Scotland's rainfall map for the period 1961-1990
The maps are the first to pinpoint future drought areas in such detail, and show that by 2080, summer rainfall in many parts of eastern Scotland will have tumbled by around 100 millimetres – one eighth of the annual average.
Particularly low-lying areas around cities and towns such as Edinburgh and Perth – which show up as deep orange on the maps – and around the Tay and Moray firths could be even more badly affected, losing up to a quarter of annual rainfall.
Such losses would mean that drinking-water reservoirs are likely to run lower for longer periods, river levels will fall, crops and trees will be more difficult to grow, and there is a greater chance of insect and disease damage.
And the projection for 2080
Conversely, the west of Scotland is expected to get wetter for longer periods.
The maps have been produced by Forestry Research, an arm of the Forestry Commission, which will this week launch a new strategy to help combat the effects of global warming.
Researchers studied three distinct periods in Scotland to draw up a picture of how rainfall patterns might change, using data produced by the UK Government's official Climate Impacts Programme (CIP).
They found that in terms of the average summer rainfall for the period between 1961 and 1990, the amount that fell in Scotland outweighed the amount that evaporated. The more sodden country was depicted in shades of green and blue for the entire summer.
But by 2050, if rainfall declined as predicted under worst-case scenarios produced by the CIP, large sections of the east coast will experience much drier summers, and an increased frequency of these conditions, leading to drought.
On the maps, this shows up as the warmer yellow areas, indicating that evaporation was outpacing rainfall and the emergence of drought-prone areas.
The 2080 map clearly reveals the areas where rainfall has declined to such an extent that water shortages may have serious drought effects.
Duncan Ray, the forest ecologist who produced the maps, said they were an assessment of the areas that would be most prone to drought in the near future.
"In the yellow to orange areas, there will be a reduction in rainfall of around 100 millimetres over the summer period," he said.
"The reservoirs will still fill in the winter but may run lower for longer periods in the summer. The problem will come if there is very little rainfall in the winter, too.
"The very low-lying areas will get less rainfall because they are in the rainshadow of the mountains to the west. The land to the east – around the Forth, the Lothians, parts of Fife, Perthshire and the Moray Firth – may get even less.
"The implications for forestry would be that certain commonly used species – such as Sitka Spruce – might have to be replaced by more drought-resistant species.
"But there are likely to be issues with agricultural crops, too. There may be a need for more irrigation in eastern Scotland."
Ray stressed that the 2080 map was based on a worst-case scenario. "There are two things that could happen," he said. "We could go on burning fossil fuels in a business-as-usual way and then this is what may happen as a result. Or we could gradually use less fossil fuels and the scenario will not be as bad as predicted."
Climate researchers are forecasting that global warming will lead to drier summers and warmer but wetter winters, with more violent storms in Scotland.
Most scientists believe the warming is being caused by concentrations of so-called greenhouse gases, such as carbon dioxide (Co2), produced by the burning of fossil fuels such as coal, oil and gas, in the atmosphere.
The current concentration, which is progressively trapping heat in the Earth's atmosphere, is now higher than at any time in the past 400,000 years and levels are expected to rise through the 21st century.
The resulting rise in global temperatures has, in turn, caused changes in rainfall patterns.
On Tuesday, in Edinburgh, the Forestry Commission will launch a Climate Change Action Plan to help mitigate the effects of global warming.
The Commission, one of Scotland's biggest landowners, will outline plans to create new woodlands to help soak up Co2 emissions and to promote the use of sustainably produced wood for a renewable source of energy and construction.
High pointsTHE long hazy days of sunshine, space hoppers and nostalgia mean that 1976 is widely regarded as being the warmest summer ever.
But Scotland's hottest season actually took place as recently as 2003. On August 9 of that year, the mercury at Greycrook in the Borders soared to 32.9°C, beating the previous Scottish high of 32.8°C in Dumfries, which was recorded in July 1908.
Although the summer was the sunniest on record at most weather-recording stations, the freakishly hot weather lasted for most of the year.
Between April 15 and 18 2003, a heatwave occurred as an anti-cyclone over Scandinavia returned westward and warm southerly winds blew across Scotland.
The temperature reached 26.9°C at Lochcarron on the 17th, setting a new record April high.
The full article contains 899 words and appears in Scotland On Sunday newspaper.
