CHAPTER 1 - WEATHER AND CLIMATE

Abstract

Atmospheric weather and climate interact with the ocean on short and long timescales, respectively. They affect the circulation, temperature and salinity of the ocean and consequently have an effect on marine ecosystems. Central England Temperature (CET) has increased by approximately 1 °C since the beginning of the 20th century, as have annual mean air temperatures over Wales, Northern Ireland and Scotland. The warmest year in CET since records began in 1659 was in 2006. The phase of the North Atlantic Oscillation (NAO) can affect the weather and climate of the UK and varies on periods of days to years. Over the past five years, the NAO has been in a positive phase, which leads to stronger winter westerly winds. The average number of storms in October to March recorded at UK stations has increased significantly over the past 50 years. However, the magnitude of storminess had similar values at the start and end of the 20th century. There remains a tendency towards wetter winters in north and west Scotland. Two out of the five wettest UK summers since records began in 1766 occurred in 2007 and 2008. Global surface temperature (assessed using a combination of changes in air temperatures over land and sea surface temperatures) has increased by about 0.75 ± 0.2 °C since the late 19th century. All ten warmest years (globally) since records began in 1850 have occurred in the 12-year period 1997–2008. Over the 21st century: all areas of the UK are predicted to get warmer, and the warming is predicted to be greater in summer than in winter; there is predicted to be little change in the amount of precipitation that falls annually, but it is likely that more will fall in the winter, with drier summers, for much of the U.K.