Until recently, fingerprint science was restrained by a lack of satellite observations — records only documented the southern tip of Greenland, making it difficult to examine the oceans around it.
The Greenland ice sheet covers almost 80% of the island country and contains enormous quantities of frozen water. The rapid melting of the Greenland ice sheet is responsible for 20% of the current sea level rise globally, and a recent study predicted its disintegration would raise global sea levels by at least 10 inches, even if people stop burning fossil fuels.
This study was possible thanks to new satellite data shared by the Copernicus Marine Service, data that spanned over 30 years and extended to higher latitudes. Coulson plugged observations of ice-thickness change into a computational model and created a prediction of sea level that spanned from 1993 to 2019. She then compared the forecast against the new satellite data — and found a perfect match.
“It was really an exciting moment for us when we first looked at that side-by-side comparison of those observations to the model predictions,” Coulson said. “The images were staggeringly similar.”
It was especially surprising because in geophysics it’s unusual to prove something is happening with a certainty of more than 99.9%, Coulson explained. But it was clear that the pattern of sea-level change revealed by the satellites was the fingerprint of the melting ice sheet — and that the estimation of sea level change predicted by both earlier models and Coulson’s new one was accurate.
“We can really say with great certainty that sea-level fingerprints exist,” Coulson said. “The theory was correct.”
Knowing fingerprints can be a tool for predicting accurate sea level change is critical because the future of the Earth’s oceans is so uncertain.