The global mean sea level has been measured by satellite altimetry to be increasing by 3mm ±0.4mm per year, resulting in more than 7cm of total sea-level rise over the last 25 years. Steve Nerem and his colleagues showed that this rate is accelerating at 0.084 ± 0.025 mm/y2. At this rate, it is possible that in 2100 the sea level will rise 65cm. This can potentially cause problems for coastal cities.
Acceleration is mainly caused by the ice melting in Greenland and Antarctica, and the expansion of sea water due to warming by an increase in greenhouse gas concentrations. The U.S/European TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 satellite missions were used to measure these increases since 1992. However, detecting acceleration is difficult due to fluctuations caused by volcanic eruptions and errors of the instruments.
This data was obtained from the satellite altimeter record of Global Mean Sea Level over the last 25 years. An approximate 7cm of total sea level rise is seen from 1993-2017.
Temperature fluctuations between the ocean and atmosphere, known as El Niños and La Niñas, could also lead to sea level fluctuations. Therefore, Nerem and his colleagues used climate models to determine the opposing phases of the El Niños Southern Oscillation in order to find the sea level acceleration more accurately. They also examined the sea level difference between altimetry and tide gauges over time to find errors, such as instrument drift, in the altimeter measurements.
Co-author John Fasullo said the study is an important role for satellite records in validating climate model projections and interpreting satellite records, such as estimating the background effects of the 1991eruption of Mount Pinatubo on global sea level.
-Anita Wang
Reference:
Sea level rise accelerating: acceleration in 25-year satellite sea level record https://www.sciencedaily.com/releases/2018/02/180212150739.htm
R. S. Nerem, B. D. Beckley, J. T. Fasullo, B. D. Hamlington, D. Masters and G. T. Mitchum. Climate-change–driven accelerated sea-level rise detected in the altimeter era. PNAS, 2018
