The US space agency, NASA, has revealed that the global sea level rise in 2024 was higher than expected, with a 0.59 cm (0.23 in) increase, surpassing the predicted 0.43 cm (0.17 in). According to NASA oceanographer Josh Willis, the ocean continues to rise at an accelerating rate. This unexpected rise is attributed to the thermal expansion of seawater, accounting for two-thirds of the increase, rather than melting 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 in Southern California. "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."
In recent years, about two-thirds of the sea level rise was from the addition of water from land into the ocean by melting ice sheets and glaciers. About a third came from thermal expansion of seawater. But in 2024, those contributions flipped, with two-thirds of sea level rise coming from thermal expansion.
"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 and the Integrated Earth System Observatory at NASA Headquarters in Washington.
Since the satellite record of ocean height began in 1993, the rate of annual sea level rise has more than doubled. In total, global sea level has gone up by 4 inches (10 centimetres) since 1993.
The warmer ocean temperatures, fuelled by record atmospheric heat, are causing sea levels to rise faster. This rapid change is also leading to marine heatwaves, devastating fisheries, and diminishing freshwater supplies. Experts emphasise that reducing greenhouse gas emissions is crucial to mitigating these impacts.
