"Since the start of the 20th century, global-mean sea level has risen faster than over any prior century in at least the last 3,000 years, and the rate of increase is accelerating," warns 'Surging Seas in Warming World' - a new United Nations (UN) report on the current and future impacts of sea level rise. Sea level is the measurement of the sea's surface height. Between the 1800s and early 1990s, tide gauges attached to structures such as piers measured global sea level, as research organization the Smithsonian Institution explains. Now satellites carry out this task by bouncing radar signals off the ocean's surface. The global sea level has risen by about 21cm since records began in 1880. While measuring in centimetres or even millimetres might seem small, these rises can have big consequences. This is particularly true where storm surges sweep further inland than they would have previously. Two main factors cause sea level rise. These are melting ice from glaciers, and seawater...
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