Over the past decade there have been predictions from scientists associated
with EPA's Office of Sea Level Rise and with various universities of a rate
of sea level rise globally up to 10 mm per year.  There is probably more of
a consensus around a 5 mm per year figure.  In some areas, land sinking
(known formally as subsidence) can increase the effect.  Subsidence is the
major reason why some parishes in coastal Louisiana are losing land to the
Gulf of Mexico at the rate of 50 feet (horizontally) per year.  As noted
earlier, volcanic islands tend to sink, which is how atolls develop in
areas where coral reefs grow.
 
The cause of our rising sea level is almost certainly the greenhouse
effect, which causes global warming, which in turn causes an increase in
melting of snow and icepack.  Hence, this is the opposite of an ice age,
which is a time when more of the earth's water budget becomes tied up in
solid form on land, causing sea level to drop.