Andrea Dutton, a University of Wisconsin-Madison geologist, recalled researchers cataloging fossil corals in Papua New Guinea, only to find their study site uplifted by a sudden earthquake, which jumbled the geological record of historic sea levels. Aside from shifting coastlines, gravitational forces can distribute water unequally across the planet.
“That’s why it’s so important to look at many sites,” Dutton said. “They all have different stories, yet clearly one thing must have happened in terms of global sea level.”