Hamlingston, B.D., Bellas-Manley, A., Willis, J.K., Fournier, S., Vinogradova, N., Nerem, R.S., C.G., Thompson, P.R. & R. Kopp (2024). The rate of global sea level rise doubled during the past three decades. Communications Earth & Science, 5, 601. https://doi.org/10.1038/s43247-024-01761-5.
As the climate changes, the ocean is impacted. Warmer climates cause the ocean to expand, because of two main reasons:
- Heat causes matter, including the ocean, to physically expand (think about how boiling water on the stove top causes the water to vaporize, therefore expanding as it becomes gaseous)
- Heat causes the ice sheets in the poles to melt, therefore adding more water to the global oceans
More volume of water in the oceans causes sea levels to rise, and coastal communities are heavily impacted.
Hamlington and his team study sea level rise by examining the Global Mean Sea Level (GMSL). Scientists study the global sea level using measurements captured by satellites, like the Sentinel-6 Michael Freilich, that was launched in 2020, as well as floats on the ocean surface. Floats and satellites measure the physical height of the global ocean surface. Then, Hamlington and his team study how the GMSL changes over time.
Hamlington’s team analyzed records from 1993-2023 yo understand how GMSL has changed in the last 30 years. They used global sea surface height measurements from satellites, and corrected for seasonal variation by averaging the heights. Hamlington determined that correction was necessary to define actual additional sea water volume, and not natural cyclic changes, like parts of the ocean warming during the spring and summer seasons.
The scientists discovered that the GMSL is increasing at an increasing rate. In 1993, the GMSL rate of change was 2.1 +/- 1.0 mm/yr. The average GMSL rate of change from 1993-2024 was 3.3 +/- 0.3 mm/yr; this value has been the accepted rate, and has been used in models for a number of years. However, their 2024 observation data indicates an average GMSL rate of change of 4.5 +/- 1.0 mm/yr.
Additionally, Hamlington and his team found from 1993 to 2023, there was a 111 mm change in GMSL. If this rate continues, an additional 169 mm of height will be gained by 2050. The team’s current trajectory suggests that the GMSL rate of change in 2050 will be 6.5 + /−2.6 mm/yr.
These discoveries significantly impact how coastal communities interact with the ocean. And, Hamlington surmised that, given their data is observational rather than modeled, this will cause a change in the mitigation strategies in helping coastal communities. The team also combined the GMSL data with local changes, and are hoping to better understand how the large-scale changes in climate will affect small-scale coastal systems.
Next, Hamlingston’s team looks forward to continuing to monitor the GMSL using the Sentinel-6 Michael Freilich Satellite. Additionally, they hope to launch another satellite in 2030, to continue this work.
I am a PhD student in Biological Oceanography at the University of Rhode Island, Graduate School of Oceanography. I completed my M.Res in Ocean Science at the University of Southampton, and completed my B.S. in Biology at Florida State University. I study deep sea coral communities and hydrothermal vent communities, especially with a focus on how physical and geological variable drive organism distribution, diversity, and change over time. When I’m not focused on school, I work with reptiles, and spend a lot of time making art for my friends and family!