2019 Yearbook

R E V I E W A N D A N A L Y S I S 25 CLIMATE CHANGE SKARA BRAE and SCOTLAND’S DYNAMIC COAST MAIRI H DAVIES O UR CLIMATE is changing at an extraordinary rate. The last century has been characterised by increasing temperatures, altering patterns of precipitation and increased frequency of unpredictable and extreme weather events. In Scotland, since the early 1960s, annual precipitation levels have increased by over 20 per cent, average annual temperatures are 1° celsius warmer, the growing season has been extended by over a month and sea level rise has accelerated to over 3mm a year. The broad future trend is anticipated to be towards warmer, wetter winters and hotter, drier summers, with sea levels continuing to rise. This has implications for the historic environment, with changing climatic conditions having potential to alter and accelerate decay processes of historic monuments and archaeological sites. Sea levels around the UK have risen by 15–20cm since 1900 and the latest sea level projections (UKCP18) are around 30 per cent higher than previous projections (UKCP09). The extent of sea level rise depends on where one is in the UK, and our future success in adhering to international agreements on the reduction of greenhouse gas emissions. However, the Met Office anticipates that sea level will continue to rise beyond 2100, even if globally we achieve a substantial reduction in emissions. In Orkney, sea level within the Bay of Skaill is expected to be up to one metre higher within our children’s lifetimes if emissions continue as they are at present. Inevitably rising sea levels will increase the rate and extent of coastal erosion, with the extent also influenced by wave height and coastal sediment supply. This will further exacerbate coastal flooding, leading to loss of, and damage to, many heritage assets. While in the past, some of Scotland’s coasts have been protected by the continuing process of isostatic uplift following the last ice age, evidence now indicates that sea level rise is outstripping this. Historic Environment Scotland (HES) and its predecessor organisations have been managing the impacts of coastal erosion for decades. Sites we look after have had sea defences in place for many years and range from prehistoric sites like Skara Brae to early modern fortifications such as Fort George. In many cases, these defences have been very effective but, of course, require A neolithic house at Skara Brae in its coastal setting, showing the survival of drystone-built furniture (Photo: Laurence Winram)