December - storms
In recent years we have experienced more frequent severe winds and larger mean wave heights in western and northern Scotland.
Weather patterns in the North Atlantic are influenced by the North Atlantic Oscillation (NAO), a pattern of opposing low-pressure systems off Iceland and high-pressure systems in the south around the Azores. Large differences in pressure lead to stormier conditions, but how much of the observed recent trend in the NOA towards stormier conditions, which is unique in its history, is due to increases in greenhouse gases is still debatable.
Mean wave heights, especially in the North Atlantic to the west and north of Scotland, have been increasing by about 2% per year over the last 50 years or so. During the same period there has been an increase in the occurrence of strong winds over the UK, leading to more severe storms. How much these changes are due to global climate change or simply natural variation is still unclear.
What is beyond dispute is that increasing storminess is leading to greater risk of damage to property and infrastructure including causeways, aquaculture installations, etc. It is also leading to a greater threat of coastal erosion and in particular the loss of low-lying habitats such as the sand dunes and machair of the Western and Northern Isles. Coastal ground and cliff nesting birds also run a greater risk of their nests being destroyed by storms.
