A new analysis by NASA has revealed that global sea levels rose at a faster pace in 2024 than previously anticipated.
Satellite data indicate that the sea level increase for the year was 0.23 inches (5.8 millimetres), exceeding the projected 0.17 inches (4.3 millimetres). Researchers attribute this discrepancy primarily to the warming of ocean waters, which causes thermal expansion.
According to scientists at NASA’s Jet Propulsion Laboratory (JPL), this trend is part of a broader acceleration in sea level rise driven by human-induced climate change.
“The rise we saw in 2024 was higher than we expected,” said Josh Willis, a sea level researcher at JPL. “Every year is a little bit different, but what’s clear is that the ocean continues to rise, and the rate of rise is getting faster and faster.”
Thermal Expansion as a Key Driver
In previous years, about two-thirds of global sea level rise was attributed to the melting of ice sheets and glaciers, with the remaining third resulting from thermal expansion—where seawater expands as it warms.
However, in 2024, these proportions reversed, with two-thirds of the rise coming from thermal expansion and only one-third from ice melt. This shift is largely due to an exceptional amount of ocean warming recorded last year.
“With 2024 as 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 physical oceanography programs at NASA.
The movement of heat within the ocean is also playing a role. Heat from the ocean’s surface is gradually penetrating deeper layers, while the natural oceanic phenomenon of El Niño is further redistributing heat across different depths.
Long-Term Trends and Acceleration
The latest findings confirm that global sea level rise is accelerating. Since satellite records began in 1993, sea levels have increased by at least 4 inches (10 centimetres). According to NASA, the rate of annual rise has more than doubled in that time.
Data from the National Oceanic and Atmospheric Administration (NOAA) show that sea levels have risen by between 8 and 9 inches (20–23 centimetres) since 1880, largely due to human-driven climate change. Scientists warn that this trend will continue, posing increasing risks to coastal communities around the world.
Recent research has also highlighted the impact on coastal cities, particularly in the United States, where some urban areas are sinking at the same time that sea levels are rising.
The combination of these factors is expected to exacerbate the risk of flooding, even in the absence of extreme weather events.
Image Credit: NASA
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