About 250 million years ago, when the Earth had no ice caps and the water around the equator was too hot for reptiles, sea level still rose and fell over time. Now, an international team of researchers has developed a way to track sea-level rise and fall and to tease out what caused the changes in the absence of ice sheets.

“Today’s models suggest .3 to 2.5 meters (1 to 8 feet) of sea-level rise during the 21st century, mainly due to ice sheet melting and thermal expansion,” said Mingsong Li, postdoctoral fellow in geoscience, Penn State. “However, we know that sea level fluctuated even during times when there were no ice sheets on Earth. The question is, what caused the fluctuation?”

The researchers reported in a recent issue of Nature Communications that the effects of the Earth’s tilt on the amounts of water in the oceans and in groundwater account for the changes in sea levels during this period, the Early Triassic.

Source: Connection of sea level and groundwater missing link in climate response