The rate of global mean sea-level rise (~3 mm/yr; SLR) has accelerated compared to the mean of the 20th century (~2 mm/yr), but the rate of rise is locally variable. Factors contributing to SLR include decreased global ice volume and warming of the ocean. On Greenland, the deficiency between annual ice gained and lost tripled between 1996 and 2007. On Antarctica the deficiency increased by 75%.