As the planet warms, the increase in sea levels threatens to uproot more than a third of the world’s population. Understanding exactly how fast and by how much they’re rising is crucial information for policy makers trying to protect communities that live near the coast, and for scientists modeling the effects of global warming. In order to predict how sea level will rise in the future, scientists need data over a long period of time. Earth observation satellites are the best tool we have to do so. We’ve been launching them into space for nearly three decades, where they orbit the earth and track data that can be used to estimate sea-level rise. But the technology they employ has remained largely the same over the years, according to NASA scientist Josh Willis.
On Saturday, Willis and his team launched the Sentinel-6 Michael Freilich satellite. The U.S. and Europe worked on the project together in the hope Sentinel-6 will be able to measure sea levels covering 90% of the world’s oceans, down to a few centimeters, for the next 10 years. Comparing the data it gathers with that of its predecessors dating back to the early 90s could help researchers predict sea-level rise over the next few decades.
“It turns out we’re great at predicting global warming, but we’re terrible at predicting sea-level rise,” said Willis. “The best way to predict it right now is to look at the last 10 or 20 or 30 years and try and extend that out into the future.”
Scientists have relied on the same method to gauge sea-level rise for decades. A radar at the bottom of the satellite shoots radio waves to the surface of the ocean and measures how long it takes the waves to hit the water and come back. The radar is supported by GPS and other positioning systems to pinpoint the location of the satellite. Comparing data over time shows how much the height of the water has changed.
There are a few new gadgets on Sentinel-6 that will help fine-tune the process. For one, its radar will be able to read data closer to the coast than before, and in finer detail. Previous instruments looked at larger areas of water at once, making it difficult to differentiate between water and land along coastlines.