Is worldwide sea level rise occurring?

Sea level has been rising continuously at a rate of approximately 2.2 mm/year during the 20th century and the last decades accelerated to 3.4 mm/year. While the past century the rise was dominated by thermal expansion of the oceans (ocean waters getting less dense due to surface warming, hence increasing in volume), the last decades the signal becomes dominated by the loss of glacier ice, melting of the Greenland ice sheet and mass loss from the Antarctic ice sheet.