Mechanisms driving ocean stratification and mixed layer deepening

This article aims to better understand the links between climate change and the recently observed significant increases in ocean stratification and the deepening of the mixed layer. Using a time series of ocean stratification data, we investigate potential “signals” of interactions with other climatic phenomena. Our findings reveal that the observed temporal patterns in stratification are primarily influenced by the El Niño-Southern Oscillation. However, this influence alone does not account for the overall increase in stratification or the deepening of the mixed layer observed since the 1960s. Instead, we demonstrate that these two phenomena are largely driven by the warming of the upper oceanic stratum (UOS). To incorporate these findings, we adapted a climate model developed in 2023, enabling it to account for the identified drivers. The enhanced model generates projections for five key global climate parameters: atmospheric temperature at the ocean level, UOS temperature, ocean cloudiness, ocean stratification, and mixed layer deepening. Our mathematical analysis of the model indicates that the relationships underlying these variables impose a clear growth trend on each of the five parameters, which eventually stabilizes toward finite limits. This stabilization results in values that remain within reasonable bounds, minimizing their impact on the planet and the global ecosystem. Under a comparable scenario, for example, the model predicts an increase of approximately 1℃ in global atmospheric temperature by 2100 – significantly lower than the 2°C increase projected by the Intergovernmental Panel on Climate Change (IPCC).
- Li G, Cheng L, Zhu J, Trenberth KE, Mann ME, Abraham JP. Increasing ocean stratification over the past half-century. Nat Clim Change. 2020;10:1116-1123.
- Sallée JB, Pellichero V, Akhoudas C, et al. Summertime increases in upper-ocean stratification and mixed-layer depth. Nature. 2021;591:592-598. doi: 10.1038/s41586-021-03303-x
- Capotondi A, Alexander MA, Bond NA, CurchitserEN, Scott JD. Enhanced upper ocean stratification with climate change in the CMIP3 models. J Geophys Res. 2012;117:C04031.
- Durack PJ, Wijfels SE. Fify-year trends in global ocean salinities and their relationship to broad-scale warming. J Clim. 2010;23:4342-4362. doi: 10.1175/2010JCLI3377.1
- Durack PJ. Ocean salinity and the global water cycle. Oceanography. 2015;28:20-31.
- Labat D, Godderis Y, Probst JL, Guyot JL. Evidence for global runoff increase related to climate warming. Adv Water Res. 2004;27:631-642.
- Zeltz É. Origins of “natural climatic nervousness” and its current accentuation. J Mod Green Energy. 2023;2:8.
- Zeltz É. Analysis of the interaction of oceanic cloudiness with the upper oceanic stratum. J Inform Anal. 2024;2:4. doi: 10.53964/jia.2024004
- Zeltz É. Analysis and climatological interpretation of the evolution of global mean temperatures since 1880. Physio- Géo. 2021;16(1):49-70.
- Hamilton JD. Time Series Analysis. Princeton, USA: Princeton University Press; 1994. p. XIV+799.
- Lacombe H. Généralités sur les Thermoclines, leur genèse et leur prévision. Exposé Introductif. La Houille/N 7/8-1974.
- Haine TWN, Curry B, Gerdes R, et al. Arctic freshwater export: Status, mechanisms, and prospects. Glob Planet Change. 2015;125:13-35.
- Trenberth, Kevin & National Center for Atmospheric Research Staff (Eds). Last modified 2024-03-20 “The Climate Data Guide: Nino SST Indices (Nino 1+2, 3, 3.4, 4; ONI and TNI).” Available from: HYPERLINK “https:// climatedataguide.ucar.edu/climate-data/nino-sst-indices-nino-12-3-34-4-oni-and-tni%20on%20%5b%20Last%20 accessed%20on%202024-12-02”https://climatedataguide. ucar.edu/climate-data/nino-sst-indices-nino-12-3-34-4- oni-and-tni on [Last accessed on 2024 Dec 02].
- Young IR, Zieger S, Babanin AV. Global trends in wind speed and wave height. Science. 2011;332:451-455. doi: 10.1126/science.1197219
- Zheng CW, Pan J, Li CY. Global oceanic wind speed trends. Ocean Coast Manage. 2016;129:15-24.
- Zieger S, Babanin AV, Young IR. Changes in Ocean Surface wind with a Focus on Trends in Regional and Monthly Mean Values. Deep Sea Research Part I Oceanographic Research Papers. 86; 2014. p. 56-67.
- Wohland J, Omrani N, Witthaut D, Keenlyside NS. Inconsistent wind speed trends in current twentieth century reanalyses. J Geophys Res-Atmos. 2019;124:1931-1940.
- Archer CL, Jacobson MZ. Evaluation of global wind power. J Geophys Res Atmos. 2005;110:D12110.
- Lindstrom EJ. NASA, Ocean in Motion: Ekman Transport Background Physical Oceanography Program. Available from: https://oceanmotion.org/html/background/ocean-in-motion.htm [Last accessed on 2024 Dec 02].
- Penhoat YD, Treguier AM. The seasonal linear response of the tropical Atlantic Ocean. J Phys Oceanogr. 1985;15: 316-329. doi: 10.1175/1520-0485(1985)015<0316:TSLROT>2.0.CO;2
- Busalacchi AJ, Picaut J. Seasonal variability from a model of the tropical Atlantic Ocean. Phys Oceanogr. 1983;13: 1564-1588. doi: 10.1175/1520-0485(1983)013<1564:SVFAMO>2.0.CO;2
- Philander SGH, Pacanowski RC. A model of the seasonal cycle in the tropical Atlantic Ocean. J Geophys Res. 1986;91:14192-14206. doi: 10.1029/JC091iC12p14192
- Garner AJ. Observed increases in North Atlantic tropical cyclone peak intensification rates. Sci Rep. 2023;13:16299. doi: 10.1038/s41598-023-42669-y
- Song J, Duan Y, Klotzbach PJ. Increasing trend in rapid intensification magnitude of tropical cyclones over the western North Pacific. Environ Res Lett. 2020;15(8):084043. doi: 10.1088/1748-9326/ab9140
- Cazenave A, Llovel W, Berthier E, Krinner G. Contributions à la hausse actuelle du niveau de la mer in: Le climat à découvert. Paris: CNRS Éditions; 2011. Available from: https://books.openedition.org/editionscnrs/11383 [Last accessed on 2024 Dec 02]. doi: 10.4000/books.editionscnrs.11383
- Gillis DP, Minns CK, Shuter BJ. Predicting open-water thermal regimes of temperate North American lakes. Can J Fish Aquat Sci. 2021;78(7):820-840. doi: 10.1139/cjfas-2020-0140
- Schertzer WM, Saylor JH, Boyce FM, Robertson DG, Rosa F. Seasonal thermal cycle of Lake Erie. J Great Lakes Res. 1987;13(4):468-486.
- Strock KE, Saros JE, McGowan S, Edlund MB, Engstrom DR. Response of boreal lakes to changing wind strength: Coherent physical changes across two large lakes but varying effects on primary producers over the 20th century. Limnol Oceanogr. 2019;64(5):2237-2251. doi: 10.1002/lno.11181
- Jiang Y, Gou Y, Zhang T, Wang K, Hu C. A machine learning approach to Argo data analysis in a thermocline. Sensors (Basel). 2017;17(10):2225. doi: 10.3390/s17102225
- Copin-Montégut G. Propriétés Physiques de l’eau de Mer; 2002. Available from: https://cahier-de-prepa.fr/tsi2-riquet/ download?id=705 [Last accessed on 2024 Dec 02].
- Le Calvé O. Propriétés physiques du milieu marin. Un cours d’introduction à l’océanographie physique. Available from: https://www.yumpu.com/fr/document/ read/17123705/ proprietes-physiques-du-milieu-marin-olivier-le-calve [Last accessed on 2024 Dec 02].
- Intergovernmental Panel on Climate Change. Special Report on the Ocean and Cryosphere in a Changing Climate. Ch. 4. Sea Level Rise and Implications for Low-Lying Islands, Coasts and Communities. Switzerland: Intergovernmental Panel on Climate Change; 2019; p. 336.
- WCRP Global Sea Level Budget Group. Global sea level budget 1993-present. Earth Syst Sci Data. 2018;10(3): 1551-1590.
- Desbruyères D, McDonagh EL, King BA, Thierry V. Global and full-depth ocean temperature trends during the early twenty-first century from Argo and repeat hydrography. J Climate. 2017;30:1985-1997. doi: 10.1175/JCLI-D-16-0396.1
- Thomas P. Fonte des glaces, dilatation thermique de l’eau et montée du niveau marin, Planet Terre. Available from: https://planet-terre.ens-lyon.fr/ressource/montee-mer.xml [Last accessed on 2024 Dec 02].
- Allan RP, Barlow M, Byrne MP, et al. Advances in understanding large-scale responses of the water cycle to climate change. Ann N Y Acad Sci. 2020;1472:49-75. doi: 10.1111/nyas.14337
- Boyer Montégut C, Madec G, Fischer AS, Lazar A, Ludicone D. Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology. J Geophys Res. 2004;109:C12003. doi: 10.1029/2004JC002378
- Masson-Delmotte V, Zhai P, Pirani A, et al. Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change; 2021. Available from: https://www.ipcc.ch/report/ ar6/wg1/downloads/report/ipcc_ar6_wgi_spm_final. pdf [Last accessed on 2024 Dec 02].
- Rahmstorf S. The concept of the thermohaline circulation. Nature. 2003;421(6924):699. doi: 10.1038/421699a
- Hasselmann K. Stochastic climate models Part I. Theory Tellus. 1976;28:473-485.
- Lin L, Von Storch H, Chen X. The stochastic climate model helps reveal the role of memory in internal variability in the Bohai and Yellow Sea. Commun Earth Environ. 2023;4:347. doi: 10.1038/s43247-023-01018-7
- Reid PC, Fischer AC, Lewis-Brown E, et al. Chapter 1. Impacts of the oceans on climate change. Adv Mar Biol. 2009;56:1-150.
- You Y. A Global Ocean Climatological Atlas of the Turner Angle: Implications for Double-Diffusion and Water-Mass Structure. Deep Sea Research Part I: Oceanographic Research Papers, 49; 2002. p. 2075-2093.
- Vilibić I, Pištalo D, Šepić J. Long-term variability and trends of relative geostrophic currents in the middle Adriatic. Continental Shelf Res. 2015;93:70-80.
- Polonsky A. The Ocean’s Role in Climate Change. NE6 2PA, UK: Cambridge Scholars Publishing, Newcastle upon Tyne; 2021.