A recent study reveals that global sea levels increased more rapidly than anticipated in 2024, coinciding with Earth recording its warmest year ever documented.
The NASA-led study attributed this to an unusually high level of ocean heating along with meltwater from terrestrial ice sources like glaciers.
"Each year shows some variations, yet one thing is evident: the ocean keeps rising higher, with an accelerating pace," stated Josh Willis, a sea level scientist at NASA’s Jet Propulsion Laboratory located in Southern California.
Worldwide sea levels are currently at their peak over the last thirty years.
Since satellite measurements of ocean levels started in 1993, the yearly increase has been notable. sea level rise has increased by over twofold. Altogether, the worldwide sea level has risen by 10 centimeters from 1993 onwards.
This extensive database has been enabled by a continuous sequence of ocean-monitoring satellites beginning with TOPEX/Poseidon in 1992.
As indicated by a NASA-led analysis based on data from the Sentinel-6 Michael Freilich satellite, 2024 witnessed a speed of sea level rise At a rate of 0.59 centimeters per year, as opposed to the anticipated rate of 0.43 centimeters per year.
The forthcoming Sentinel-6B satellite will keep tracking sea surface height with precision up to several centimeters across roughly 90 percent of the globe's oceans.
Anthropogenic warming is a major contributor to rising sea levels.
In recent times, approximately two-thirds of the increase in sea levels has been due to the influx of water from melting ice sheets and glaciers into the oceans. The remaining one-third can be attributed to the expansion of seawater caused by rising temperatures.
However, in 2024, those contributions reversed, with two-thirds of sea level rise coming from thermal expansion.
"2024 has been recorded as the warmest year ever, with Earth's rising seas also hitting their peak levels in thirty years," stated Nadya Vinogradova Shiffer, who leads the physical oceanography programs at NASA headquarters in Washington.
What does the term "thermal expansion of water" refer to?
Several methods allow heat to enter the ocean, leading to an increase in water temperature and subsequent expansion.
Typically, seawater organizes itself into layers based on water temperature and density.
Warm water is less dense and rises above colder, more dense water. Typically, the heat from the surface penetrates very gradually downwards through these layers into deeper waters. ocean .
However, highly breezy regions of the sea can stir up the layers sufficiently to cause vertical mixing.
Large-scale currents, such as those observed in the Southern Ocean, have the ability to shift oceanic layers, facilitating the descent of surface water into deeper regions with greater ease.
During an El Niño event, when a substantial body of warm water from the western Pacific moves towards the central and eastern parts of the ocean, this significant displacement of water can trigger upward thermal movements within the sea.
The United Nations has cautioned that increasing sea levels pose a significant threat to large populations residing on islands or near shorelines.
Especially susceptible regions encompass low-lying areas. coastal communities In India, Bangladesh, China, and the Netherlands, along with island nations In the Pacific and Indian Oceans.