On March 21, the National Aeronautics and Space Administration (NASA) announced that sea levels rose by 76mm during the period from 2022 to 2023, nearly four times the increase observed from 2021 to 2022, attributed to the strong El Niño weather phenomenon and global warming.
The analysis led by NASA is based on over 30 years of satellite observations, with the first satellite launched in 1992 and the most recent one in 2020. Overall, sea levels have increased by approximately 101mm since 1993. The rate of sea-level rise has also accelerated, more than doubling from over 1.7mm per year in 1993 to more than 4.3mm per year at present.
Waves washing over the boardwalk at Mission Beach in San Diego during the king tide event in December 2023. (Photo: scripps.ucsd.edu).
The direct cause of this surge is the El Niño phenomenon, which has replaced the La Niña conditions from 2021 to 2022, during which sea levels rose by approximately 2.03mm. Furthermore, human factors are clearly one of the contributors to this situation.
Nadya Vinogradova Shiffer, head of NASA’s sea level monitoring team and ocean physics program in Washington, stated that at the current rate, global average sea levels are on track to increase by an additional 20cm by 2050. This figure will be double that over the next three decades compared to the previous century, resulting in more frequent and devastating floods in the future compared to today.
Sea level researcher Josh Willis at NASA’s Jet Propulsion Laboratory (JPL) noted that during years with El Niño, significant amounts of rain typically fall on land and flow into the ocean, temporarily raising sea levels.
According to Ben Hamlington, the head of NASA’s sea level monitoring team at JPL, long-term datasets such as the 30-year satellite record allow the research team to distinguish short-term impacts on sea level, such as those from El Niño, from trends indicating where sea levels are heading. Technological innovations have improved the accuracy of measurements over the years.
