Today’s Video of the Day from NASA Earth Observatory describes how Earth-observing satellites give us the ability to track sea level rise with unprecedented accuracy.
“Thirty years ago, scientists and engineers launched a new satellite to study the rising and falling of seas over time, a task that once could only be done from the coast. TOPEX/Poseidon rocketed into space on August 10, 1992, and started a 30-year record of ocean surface height around the world,” says NASA.
Analysis of the TOPEX data confirmed that sea levels are rising at an increasingly fast pace. The observations have revealed that the global acreage sea level has risen 10.1 centimeters (3.98 inches) since 1992.
“Starting with TOPEX/Poseidon, NASA and partner space agencies have flown a continuous series of satellites that use radar altimeters to monitor ocean surface topography – essentially, the vertical shape and height of the ocean.”
“Radar altimeters continually send out pulses of radio waves (microwaves) that reflect off the ocean surface back toward the satellite. The instruments calculate the time it takes for the signal to return, while also tracking the precise location of the satellite in space. From this, scientists derive the height of the sea surface directly underneath the satellite,” explains NASA.
The collective satellite record of sea level rise is now long enough that it is possible for experts to identify changes beyond seasonal or natural variation.
“With 30 years of data, we can finally see what a huge impact we have on the Earth’s climate,” said Josh Willis, an oceanographer at the Jet Propulsion Laboratory. “The rise of sea level caused by human interference with the climate now dwarfs the natural cycles. And it is happening faster and faster every decade.”
“What stands out from the satellite altimetry record is that the rise over 30 years is about ten times bigger than the natural exchange of water between ocean and land in a year. In other words, the human-caused rise in global sea level is now ten times bigger than the natural cycles.”
Image/Video Credit: NASA Earth Observatory
Joshua Stevens, using TOPEX/Poseidon data courtesy of Josh Willis/JPL-Caltech