The Sources of Sea‐Level Changes in the Mediterranean Sea Since 1960. Issue 9 (26th September 2022)

• Record Type: Journal Article
• Authors: Calafat, F. M.; Frederikse, T.; Horsburgh, K.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 9(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-26
• Subjects: sea level -- Mediterranean -- sterodynamic -- ice melting -- reconstruction -- Bayesian; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2022JC019061
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Past sea‐level changes in the Mediterranean Sea are highly non‐uniform and can deviate significantly from both the global average sea‐level rise and changes in the nearby Atlantic. Understanding the causes of this spatial non‐uniformity is crucial to the success of coastal adaptation strategies. This, however, remains a challenge owing to the lack of long sea‐level records in the Mediterranean. Previous studies have addressed this challenge by reconstructing past sea levels through objective analysis of sea‐level observations. Such reconstructions have enabled significant progress toward quantifying sea‐level changes, however, they have difficulty capturing long‐term changes and provide little insight into the causes of the changes. Here, we combine data from tide gauges and altimetry with sea‐level fingerprints of contemporary land‐mass changes using spatial Bayesian methods to estimate the sources of sea‐level changes in the Mediterranean Sea since 1960. We find that, between 1960 and 1989, sea level in the Mediterranean fell at an average rate of −0.3 ± 0.5 mm yr −1, due to an increase in atmospheric pressure over the basin and opposing sterodynamic and land‐mass contributions. After 1989, Mediterranean sea level started accelerating rapidly, driven by both sterodynamic changes and land‐ice loss, reaching an average rate of 3.6 ± 0.3 mm yr −1 in the period 2000–2018. The rate of sea‐level rise shows considerable spatial variation in the Mediterranean Sea, primarily reflecting changes in the large‐scale circulation of the basin. Since 2000, sea level has been rising faster in the Adriatic, Aegean, and Levantine Seas than anywhere else in the Mediterranean Sea. Plain Language Summary: The rate of sea‐level rise varies considerably across the Mediterranean basin. Characterizing this geographic variability is essential for the design of coastal adaptation plans. This, however, is no easy feat because of the sparseness of the observational sea‐level record. In the Mediterranean Sea, long tide gauge records are restricted to a few locations along the European coastlines. Satellite altimetry provides sea‐level observations with better spatial coverage but only since 1992. Past studies have addressed the difficulties related to data sparseness by combining data from tide gauges and altimetry to produce sea‐level reconstructions. However, existing sea‐level reconstructions have difficulty capturing long‐term changes and do not distinguish between the causes of the changes. Here, we analyze sea‐level observations in combination with fingerprints of land‐ice melting using probabilistic methods to show that the average rate of sea‐level rise in the Mediterranean Sea increased from −0.3 mm yr −1 in the period 1960–1989 to 3.6 mm yr −1 in 2000–2018, as a result of increased ocean warming and land‐ice melting. Furthermore, we find that, since 2000, sea‐level in the Adriatic, Aegean, and Levantine Seas has been rising faster than anywhere else in the Mediterranean Sea, due to changes in the circulation of the basin. Key Points: The average rate of sea‐level rise in the Mediterranean Sea increased from −0.3 mm yr −1 in the period 1960–1989 to 3.6 mm yr −1 in 2000–2018 Sterodynamic and land‐mass changes both have made comparable contributions to the Mediterranean sea‐level rise since 2000 Since 2000, sea level has been rising faster in the Adriatic, Aegean, and Levantine Seas than anywhere else in the Mediterranean Sea