How do oxygen isotope measurements provide information about global sea levels?

Question

How do oxygen isotope measurements provide information about global sea levels?

Answer 1

I am pretty sure that there is an indirect relationship between oxygen isotope levels and global sea levels....an oxygen isotope is an oxygen molecule with slightly more or less neutrons then the stable state thus changing its atomic mass....ultimately it is still an oxygen molecule but its called a different species......

if the molecule is slightly larger (by having more neutrons) it will affect the rate of evaporation....so by looking in ice cores and calculating the ratio of oxygen isotopes we can tell if it was warmer (more of the heavier isotopes) or if it was cooler (equal amounts).  This is because a larger molecule (the isotope) will not evaporate as readily as the other species.  So if there is a lot of just the heavier isotope that means that there was warmer temperatures and the other species were evaporated away.  

This means that we can relate the isotope levels to temperature and also global atmospheric conditions and then to sea level.  We are beginning to understand a bit more about the mechanisms behind global sea level rise and fall, so by looking at the isotopes we can go down the line and eventually get to the sea level...(although the further down the line you go the less confident you are in your results)