NASA analysis shows global sea level rise exceeded scientists' expectations in 2024
Nature on Earth often shifted and shaped itself with the influence of various natural forces, both visible and invisible. Scientists have been busy in understanding these shifts, as data in the past have often shown unexpected patterns. NASA led a similar study in 2024 that measured the global rise in sea levels and the result was alarming. It was found that the sea level rose faster than anticipated by scientists in the same year due to the expansion of ocean water, as it became warm or because of thermal expansion. Precise monitoring was made possible by advancements in technology, which helped review situations that now require immediate attention.
The rise in sea level last year was measured up to 0.23 inches, compared to the expected rate of 0.17 inches. Lately, around two-thirds of the rise was attributed to the melting ice sheets and glaciers which added water from land into the ocean. Another third was from the thermal expansion of seawater. But all of this got flipped in 2024, when thermal expansion contributed to two-thirds of the sea level rise. “The rise we saw in 2024 was higher than we expected,” stated a sea-level researcher at NASA’s Jet Propulsion Laboratory named Josh Willis, about the unusual phenomenon, according to NASA.
The satellite record of water levels began in 1993 and since then, the rate of increase in the level has doubled, with an overall increase since 1993 totaling to 4 inches. Ocean-observing satellites have made it possible to record these rises uninterrupted, starting with TOPEX/Poseidon in 1992. 2020's Sentinel-6 Michael Freilich satellite is the latest addition to this series. An upcoming Sentinel-6B satellite would be its identical pair that would carry this sea level data for around 90% of the world’s oceans.
“With 2024 as the warmest year on record, Earth’s expanding oceans are following suit, reaching their highest levels in three decades,” shared Nadya Vinogradova Shiffer, the head of physical oceanography programs at NASA, according to NASA Sea Level Change Observations from Space. It was highlighted by researchers that there were various ways in which heat was absorbed into the ocean that caused the thermal expansion of water. Seawater usually arranged itself in layers based on its temperature and density. Warm water flowed on top as it was lighter than the cooler layer, which had more density.
In several regions, heat from the surface moves slowly through these layers and passes down the temperature. However, areas of the ocean that had high winds could liven up the layers of water and cause them to vertically mix up. If the current was large enough, it could tilt the ocean layers and allow the surface water to seep through the depths more easily. This was the kind of ocean climate that could be observed in areas like the Southern Ocean. This unexpected movement of water with great currents resulted in the vertical movement of heat within the ocean. The process was further accelerated during El Niño.
El Niño is the process by which a large pool of warm water, usually located in the western Pacific Ocean, sloshes towards the Americas. Such phenomena result in increased thermal expansion of water which contributed to the recent rise in sea levels. As environmental conditions further deteriorate, these shifts in ocean levels could pose a threat to our existence. The rate of glacial melting did not experience a decrease and the planet is getting heated from within the core. Immediate resolution to take action for climate change is a need of the hour and this study further emphasizes the urgency.
