Normally, two-thirds of sea level rise is due to melting ice from mountain glaciers and Greenland and Antarctic ice caps, and one-third from the thermal expansion of the oceans.
Last year, the hottest year on record, this was reversed, with warmer water accounting for two-thirds of the sea level rise of 0.59cm (0.23in) – considerably more than the 0.43cm scientists were expecting. Nasa, the US agency that produces the figures from its satellite data, believes that the mixing of hotter surface waters with cooler sea at depth during an El Niño year may have caused this unexpected blip, although more violent winds could also have been a contributing factor.
