Ocean Processes Feeder Report

Abstract

We assess the physical state of the UK’s seas and so provide a context for the clean, healthy, safe, productive and biologically diverse aspects in the other Charting Progress 2 Feeder Reports. UK annual mean temperature has risen by approximately 1°C since the beginning of the 20th Century. 2006 was the warmest year in central England since records began in the seventeenth century. Sea-surface temperature has risen by between 0.5 and 1 degree C from 1871 to 2000. Warming since the mid 1980s has been more pronounced in regions 2, 5 and 6 (southern North Sea, Irish and Hebridean seas). Oceans are acidifying (pH decreasing) as carbon dioxide is absorbed. We have no baseline measurements of pH against which changes in UK waters can be judged, and it will be some time before we can make accurate judgements about the rate of acidification relative to natural annual and inter- annual cycles of pH. Mean sea level around the UK coast rose by about 1.4mm per year during the 20th century. Circulation, suspended particulate matter, turbidity, salinity and waves vary on daily to inter-annual timescales but show no significant trend over the last decade, except for a slight salinity decrease in region 2 (southern North Sea) and a slight increase in salinity in the (northern) regions 1, 7 and 8