Why are sea levels rising ONLY 2mm per year?
If all the ice in the world melted, the sea level rise would be somewhere around 200 feet or 61,000mm. So far only a tiny portion of the total ice has melted. It looks like a lot in the Arctic, but the ice there is very thin, and it is also floating ice, which doesn’t increase the seal level, as was mentioned above. Most of the ice in the world is in Antarctica, where it is up to two miles thick. That has barely started to melt. The global temperature has only increased around 1.5 deg. C in the last 150 years. Even if it goes up a lot more, it will take hundreds of years for all the ice to melt. The sea level rise might get faster, but it will still only be a few mm per year.
Much of the ice that is melting so far is floating sea ice. When that melts, it doesn’t change the level of water since the ice was displacing the same volume of water as it will add when it melts, and the oceans have huge volumes. When the ice on land in Greenland and Antarctica melts, then really rapid sea level changes will take place. Perhaps as much as several centimeters per year or more. The ice on land is not displacing any ocean water where it is, so when it melts almost 100% of its volume goes towards sea level change or atmospheric water vapor (water vapor is a major greenhouse gas so that would add to the melting, BTW).
