Has sea level changed in the past?
Sea leval has varied by over 100 metres during glacial-interglacial cycles as the major ice sheets have waxed and waned. Sea level was about 4 to 6 metres above present day values during the last interglacial period, when Greenland was about 3C warmer than today. The rate of sea level rise over the last 20 years in 25 per cent faster than any rate during the previous 115 years, almost twice as fast as the average over the twentieth century, which was in turn an order of magnitude larger than the rate of rise over the two millennia prior to the eighteenth century. Why is sea level rising? The two major reasons for sea level rise are thermal expansion of ocean waters as they warm and an increase in the ocean mass, principally from land-based sources of ice (glaciers and ice caps and the ice sheets of Greenland and Antarctica). Global warming from increasing greenhouse gas concentrations is a significant driver of both contributions. Projections of future sea level change During the twent
