The earth has been in a long-term warming trend for 20,000 years, since the end of the last ice age. There are other cycles (30-yerar, 1000-year) superimposed on this 100,000-year ice age cycle. During the last 20,000 years sea levels have risen about 300 feet, or an average of 18 inches per century. All from natural causes of course. This will continue until the world temperatures start dropping prior to the next ice age, probably within the next few thousand years.
Currently the rate of rise is less than that, indicating that humans have not really changed the equation. Long term temperature vs. CO2 graphs indicate that CO2 concentrations react to changes in temperature more than the other way around.