About 71 percent of the Earth is covered by water, so measuring sea level changes around the world is no small feat. Up until now, scientists believed they knew how much global sea level had risen during the 20th century. This number has hovered around 0.6 inches per decade since 1900, according to the National Oceanic and Atmospheric Administration, and has been partly driven by warming ocean temperatures.
By Sarah Emerson | MOTHERBOARD
But a new study, published this month to Geophysical Research Letters, found evidence to suggest that historical sea level records have been off—way off in some areas—by an underestimation of 5 to 28 percent. Global sea level, the paper concluded, rose no less than 5.5 inches over the last century, and likely saw an increase of 6.7 inches.
The reason for this discrepancy was uncovered by earth scientists at NASA’s Jet Propulsion Laboratory and the University of Hawai’i at Mānoa. By comparing newer climate models with older sea level measurements, the team discovered that readings from coastal tide gauges may not have been as indicative as we thought. These gauges, located at more than a dozen sites across the Northern Hemisphere, have been a primary data source for estimating sea level changes during the last several decades.