The ocean floor may be sinking under the weight of heavier oceans as a result of climate-change-induced glacier melting and sea level rise, according to a new study. Scientists at Delft University of Technology in the Netherlands discovered that the deforming impact of a heavier ocean on the seafloor is too large to be accurately measured using traditional satellite altimeters. This means that measurements of sea level rise based on the assumption of a static seafloor may be inaccurate.
Researchers suspected that traditional sea level measurement methods might be off. “We have had tide gauge sea level rise measurements for more than a century,” Delft University of Technology geoscientist and study Thomas Frederikse told Earther. “You put an instrument at the sea bottom and see how far sea level changes relative to the bottom. Satellites orbiting the Earth measure sea level from space. We wanted to see how large is the difference.” After modeling and analysis of new data, the team determined that, as a result of sea level rise and climate change, the ocean floor had been sinking on average by about 0.1 mm/year between 1993-2014, or 2.1 mm in total. This relatively small change can have a big impact on the accuracy, or inaccuracy, of sea level measurements if not taken into account.
In their study recently published in Geophysical Research Letters, researchers determined that traditional satellite measurements are underestimating sea level rise by about four percent. Now that this disparity is known, corrections can be made. “The effect is systematic and relatively easy to account for,” wrote Frederikse and his co-authors.
Over the course of the study, the researchers uncovered some unexpected impacts of heavier oceans, including a slight ocean floor rise in areas most impacted by sea ice and glaciers, such as Greenland and the Arctic. The small but significant change in our measurements of sea level is a reminder of all that we still do know about climate change and its impacts on every part of this planet. “The Earth itself is not a rigid sphere, it’s a deforming ball,” said Frederikse, according to Earther. “With climate change, we do not only change temperature.”