More than one reason, of course. I would never expect you to buy into a statement that sea level is rising only because of green house gasses.
A lot of things are changing not just the sea level. If you search the topic mid-year you won’t find things on EPA and NOAA sites like you would have last year. Our President and his advisers don’t understand the science and have an many cases call it all a hoax. Some things still exist. Yes, there are different reasons for a rise the relative sea level in different locations. But if you study this graph I just retrieved from NOAA you can see some factors.
Take a close look and you see a black line showing changes in sea level. It’s not in meters is in a much smaller measurement using rather accurate instruments. Focusing on 10 years. (most of the date, after 2012 is hidden from access at this point for some reason).
We know that as water is warmed it expands. But don’t forget a point of water freezing it expands. Oh yea that changes its density and ice floats. But its not melting alone, if its above sea level and melts or runs into the ocean it increases sea level. So NOAA has done the math and is showing you in the graph where the water came from to cause sea level to be higher.
I would say the thermal expansion is from warming the oceans water.
I would also say that warmer air will add to melting of ice.
I will go a step further and say, that black carbon settling on ice and snow will cause it to absorb more solar energy from a photon of sun. Presto, it warms faster and is more likely to melt and run off to the sea, or lets say flow into the sea increasing sea level.
In recent years we put more emphasis in education on deductive reasoning and with the know facts I stated you might now be able to reach a conclusion or educated understanding of what is happening thanks to science.
The chart was retrieved Jun 6, 2017 from https://www.climate.gov/news-features/understanding-climate/climate-change-global-sea-level If that page remains unaltered it contains the full references for the data.
Please post your conclusion: