Thirion G., Birol F., Jouanno Julien. (2024). Loop current eddies as a possible cause of the rapid sea level rise in the Gulf of Mexico. Journal of Geophysical Research : Oceans, 129 (3), e2023JC019764 [23 p.]. ISSN 2169-9275.
Source
Journal of Geophysical Research : Oceans, 2024,
129 (3), e2023JC019764 [23 p.] ISSN 2169-9275
The Gulf of Mexico (GOM), with its densely populated coastline, is one of the world's most vulnerable regions to climate change and sea level (SL) rise. Over the last three decades, various works have been conducted to assess coastal SL trends around the basin using tide gauge stations, separately from studies dealing with regional dynamical processes. Using altimetry, Argo, and eddy atlas products over the period from January 1993 to December 2020, we have analyzed the regional SL variations in the area to define their characteristics and explore their possible dynamical causes. We observe a mean GIA-corrected SL rise rate of 4.81 +/- 0.85 mm yr-1, which is 25% higher than that of the adjacent Caribbean Sea and 44% higher than that of the global ocean. This result highlights the singular SL evolution in the GOM over the 28-year study period. Over 2010-2020, the SL trend in the GOM has even accelerated, along with a strong warming of the upper-layer (0.58 +/- 0.17 degrees C), which explains similar to 60% of the SL rise rate through the thermosteric effect. Finally, the heat input estimates emphasize the role of the Loop Current eddies as a major contributor to the recent acceleration of SL rise due to upper-layer warming. While it is generally accepted that global SL is rising as a result of climate change, the rate of rise varies depending on the ocean area being studied. Using devices called tide gauges, researchers have shown that the SL has risen sharply along the densely populated coasts of the GOM. However, little research has been done on the causes of this phenomenon throughout the basin. Oceanographers know that SL variations depend on several parameters such as heat input. Indeed, the warmer the water, the more its volume increases, leading to a rise in SL. Using satellite data, we show that the surface waters of the Gulf have warmed since the early 2010s, and that SL rise there is faster than in the adjacent Caribbean where no such warming has occurred. This difference may be related to the large warm-water eddies generated by the Loop Current. Indeed, the larger the eddies, the more heat they carry with them. Yet, our results show that the size of these eddies has increased in recent years and that they could be a major contributor to the surface water warming and ultimately to the SL rise in the area. Sea level rise (SLR) trend in the Gulf of Mexico is 44% higher than the global mean sea level trend over the period 1993-2020 This trend has accelerated since similar to 2010, along with a deep upper-layer warming that explains more than half of the SLR through steric effects Loop Current eddies may be responsible for this acceleration
