A NASA-led analysis has revealed that global sea levels rose faster than anticipated in 2024, driven by an unusual amount of ocean warming. The recorded rate of rise was 0.23 inches (0.59 cm) per year, exceeding the expected 0.17 inches (0.43 cm) per year. This increase was largely attributed to thermal expansion, as warming waters expand, along with contributions from melting ice sheets and glaciers.
“The rise we saw in 2024 was higher than we expected,” said Josh Willis, a sea level researcher at NASA’s Jet Propulsion Laboratory. “Every year is a little different, but what’s clear is that the ocean continues to rise, and the rate of rise is getting faster.”
Typically, about two-thirds of sea level rise comes from melting glaciers and ice sheets, with thermal expansion accounting for the remaining third. However, in 2024, this pattern reversed, with thermal expansion contributing the most.
“With 2024 being the warmest year on record, Earth’s expanding oceans are following suit, reaching their highest levels in three decades,” said Nadya Vinogradova Shiffer, head of NASA’s physical oceanography programs.
Since satellite measurements of ocean height began in 1993, global sea levels have risen by approximately 4 inches (10 cm), with the annual rate of increase more than doubling. The long-term dataset has been maintained by a continuous series of ocean-observing satellites, starting with TOPEX/Poseidon in 1992. The current satellite, Sentinel-6 Michael Freilich, launched in 2020, and its twin, Sentinel-6B, is set to continue precise sea level measurements for years to come.
Heat enters the ocean in several ways, influencing thermal expansion. Normally, warm water remains at the surface, while denser, cooler water stays below. However, in regions with strong winds or powerful ocean currents, such as those in the Southern Ocean, vertical mixing can occur, redistributing heat to deeper waters.
El Niño events, where warm water shifts from the western to the central and eastern Pacific, can also cause significant vertical movement of heat within the ocean, further influencing sea level changes.
As the planet continues to warm, scientists stress the importance of monitoring sea level trends to better understand the long-term impacts of climate change.
Bd-pratidin English/ Jisan
