“Rising sea levels” is among the most common phrases one reads and hears whenever discussions of climate change- particularly anthropogenic climate change – occur. But on a planet where oceans cover over seventy percent of the surface, just how is sea level measured? And for that matter, given changes in technology, as well as in the recent increase in interest in shifting baselines and how they may affect historical data in many of the biological and Earth sciences, have the ways sea level has been measured in the past changed?
