Sea levels have been rising by about 1.7 mm per year over the past 55 years. However, from 1993 to 2002, coastal sea levels rose faster than the global average. In fact, the rate of coastal sea level rise in the 1990s was higher than in any other decade since 1955. This could be a sign that global sea levels will also rise faster in the future. The researchers used data from tide gauges and altimeters to make these observations.