Weakening of the Atlantic Meridional Overturning Circulation abyssal limb in the North Atlantic

Orsi, A. H., Johnson, G. C. & Bullister, J. L. Circulation, mixing, and production of Antarctic Bottom Water. Prog. Oceanogr. 43, 55–109 (1999).

Article  Google Scholar 

Lumpkin, R. & Speer, K. Global ocean meridional overturning. J. Phys. Oceanogr. 37, 2550–2562 (2007).

Article  Google Scholar 

Johnson, G. C. Quantifying Antarctic Bottom Water and North Atlantic Deep Water volumes. J. Geophys. Res. 113, C05027 (2008).

Google Scholar 

Johnson, G. C. et al. Global oceans: ocean heat content. Bull. Am. Meteorol. Soc. 99, Si–S310 (2018).

Google Scholar 

Bagnell, A. & DeVries, T. 20th century cooling of the deep ocean contributed to delayed acceleration of Earth’s energy imbalance. Nat. Commun. 12, 4604 (2021).

Article  CAS  Google Scholar 

Purkey, S. G. & Johnson, G. C. Warming of global abyssal and deep Southern Ocean waters between the 1990s and 2000s: contributions to global heat and sea level rise budgets. J. Climate 23, 6336–6351 (2010).

Article  Google Scholar 

Kouketsu, S. et al. Deep ocean heat content changes estimated from observation and reanalysis product and their influence on sea level change. J. Geophys. Res. 116, C03012 (2011).

Google Scholar 

Zenk, W. & Morozov, E. Decadal warming of the coldest Antarctic Bottom Water flow through the Vema Channel. Geophys. Res. Lett. 34, L14607 (2007).

Article  Google Scholar 

Johnson, G. C., Purkey, S. G. & Toole, J. M. Reduced Antarctic meridional overturning circulation reaches the North Atlantic Ocean. Geophys. Res. Lett. 35, L22601 (2008).

Article  Google Scholar 

Desbruyères, D. G., Purkey, S. G., McDonagh, E. L., Johnson, G. C. & King, B. A. Deep and abyssal ocean warming from 35 years of repeat hydrography. Geophys. Res. Lett. 43, 10,356–10,365 (2016).

Article  Google Scholar 

Menezes, V. V., Macdonald, A. M. & Schatzman, C. Accelerated freshening of Antarctic Bottom Water over the last decade in the southern indian ocean. Sci. Adv. https://doi.org/10.1126/sciadv.1601426 (2017).

Purkey, S. G. et al. Unabated bottom water warming and freshening in the South Pacific ocean. J. Geophys. Res.: Oceans 124, 1778–1794 (2019).

Article  Google Scholar 

Johnson, G. C., Purkey, S. G., Zilberman, N. V. & Roemmich, D. Deep Argo quantifies bottom water warming rates in the southwest Pacific Basin. Geophys. Res. Lett. 46, 2662–2669 (2019).

Article  Google Scholar 

Strass, V. H., Rohardt, G., Kanzow, T., Hoppema, M. & Boebel, O. Multidecadal warming and density loss in the deep Weddell Sea, Antarctica. J. Climate 33, 9863–9881 (2020).

Article  Google Scholar 

Johnson, G. C. Antarctic Bottom Water warming and circulation slowdown in the Argentine Basin from analyses of deep Argo and historical shipboard temperature data. Geophys. Res. Lett. https://doi.org/10.1029/2022GL100526 (2022).

van Wijk, E. M. & Rintoul, S. R. Freshening drives contraction of Antarctic Bottom Water in the Australian Antarctic Basin. Geophys. Res. Lett. 41, 1657–1664 (2014).

Article  Google Scholar 

Purkey, S. G. & Johnson, G. C. Global contraction of Antarctic Bottom Water between the 1980s and 2000s. J. Clim. 25, 5830–5844 (2012).

Article  Google Scholar 

Masuda, S. et al. Simulated rapid warming of abyssal North Pacific waters. Science 329, 319–322 (2010).

Article  CAS  Google Scholar 

Nakano, H. & Suginohara, N. Importance of the eastern Indian Ocean for the abyssal Pacific. J. Geophys. Res.: Oceans 107, 3219 (2002).

Google Scholar 

Patara, L. & Böning, C. W. Abyssal ocean warming around Antarctica strengthens the Atlantic overturning circulation. Geophys. Res. Lett. 41, 3972–3978 (2014).

Article  Google Scholar 

Khatiwala, S., Primeau, F. & Holzer, M. Ventilation of the deep ocean constrained with tracer observations and implications for radiocarbon estimates of ideal mean age. Planet. Sci. Lett. 325–326, 116–125 (2012).

Article  Google Scholar 

Solodoch, A. et al. How does Antarctic Bottom Water cross the Southern Ocean? Geophys. Res. Lett. https://doi.org/10.1029/2021GL097211 (2022).

Silvano, A. et al. Observing Antarctic Bottom Water in the Southern Ocean. Front. Mar. Sci. https://doi.org/10.3389/fmars.2023.1221701 (2023).

Campos, E. J. D. et al. Warming trend in Antarctic Bottom Water in the Vema Channel in the South Atlantic. Geophys. Res. Lett. https://doi.org/10.1029/2021GL094709 (2021).

Li, Q., England, M. H., Hogg, A. M., Rintoul, S. R. & Morrison, A. K. Abyssal ocean overturning slowdown and warming driven by Antarctic meltwater. Nature 615, 841–847 (2023).

Article  CAS  Google Scholar 

Frajka-Williams, E., Cunningham, S. A., Bryden, H. & King, B. A. Variability of Antarctic Bottom Water at 24.5° N in the Atlantic. J. Geophys. Res.: Oceans https://doi.org/10.1029/2011JC007168 (2011).

Desbruyères, D., McDonagh, E. L., King, B. A. & Thierry, V. Global and full-depth ocean temperature trends during the early twenty-first century from Argo and repeat hydrography. J. Clim. 30, 1985–1997 (2017).

Article  Google Scholar 

Schmitz, W. J. & McCartney, M. S. On the North Atlantic circulation. Rev. Geophys. 31, 29–49 (1993).

Article  Google Scholar 

Talley, L. D., Pickard, G. L., Emery, W. J. & Swift, J. H. Descriptive Physical Oceanography: An Introduction 6th edn (Academic Press, 2011).

Herrford, J., Brandt, P. & Zenk, W. Property changes of deep and bottom waters in the western tropical Atlantic. Deep Sea Res. Part I 124, 103–125 (2017).

Article  Google Scholar 

Cunningham, S. A. & Alderson, S. Transatlantic temperature and salinity changes at 24.5° N from 1957 to 2004. Geophys. Res. Lett. https://doi.org/10.1029/2007GL029821 (2007).

Johnson, G. C., Cadot, C., Lyman, J. M., McTaggart, K. E. & Steffen, E. L. Antarctic Bottom Water warming in the Brazil Basin: 1990s through 2020, from WOCE to Deep Argo. Geophys. Res. Lett. https://doi.org/10.1029/2020GL089191 (2020).

Johnson, G. C., Robbins, P. E. & Hufford, G. E. Systematic adjustments of hydrographic sections for internal consistency. J. Atmos. Oceanic Technol. 18, 1234–1244 (2001).

Article  Google Scholar 

Wright, W. R. Northward transport of Antarctic Bottom Water in the western Atlantic Ocean. Deep Sea Res. 17, 367–371 (1970).

Google Scholar 

Mauritzen, C., Polzin, K. L., McCartney, M. S., Millard, R. C. & West-Mack, D. E. Evidence in hydrography and density fine structure for enhanced vertical mixing over the Mid-Atlantic Ridge in the western Atlantic. J. Geophys. Res. 107, 3147 (2002).

Google Scholar 

Kanzow, T. Monitoring the Integrated Deep Meridional Flow in the Tropical North Atlantic. Ph.D. thesis, Christian-Albrechts Universität Kiel (2004).

Spall, M. A. Wave-induced abyssal recirculations. J. Mar. Res. 52, 1051–1080 (1994).

Article  Google Scholar 

Biló, T. C. & Johns, W. E. The Deep Western Boundary Current and adjacent interior circulation at 24°–30° N: mean structure and mesoscale variability. J. Phys. Oceanogr. 50, 2735–2758 (2020).

Article  Google Scholar 

Kanzow, T., Send, U., Zenk, W., Chave, A. D. & Rhein, M. Monitoring the integrated deep meridional flow in the tropical North Atlantic: long-term performance of a geostrophic array. Deep Sea Res. Part I 53, 528–546 (2006).

Article  Google Scholar 

Limeburner, R., Whitehead, J. A. & Cenedese, C. Variability of Antarctic Bottom Water flow into the North Atlantic. Deep Sea Res. Part II 52, 495–512 (2005).

Article  Google Scholar 

Desbruyères, D. G. et al. Warming-to-cooling reversal of overflow-derived water masses in the Irminger Sea during 2002–2021. Geophys. Res. Lett. 49, 1–10 (2022).

Article  Google Scholar 

Zhou, S. et al. Slowdown of Antarctic Bottom Water export driven by climatic wind and sea-ice changes. Nat. Clim. Change 13, 701–709 (2023).

Article  Google Scholar 

Meredith, M. P., Garabato, A. C. N., Gordon, A. L. & Johnson, G. C. Evolution of the deep and bottom waters of the Scotia Sea, Southern Ocean, during 1995–2005*. J. Clim. 21, 3327–3343 (2008).

Article  Google Scholar 

Meinen, C. S., Perez, R. C., Dong, S., Piola, A. R. & Campos, E. J. D. Observed ocean bottom temperature variability at four sites in the northwestern Argentine Basin: evidence of decadal deep/abyssal warming amidst hourly to interannual variability during 2009–2019. Geophys. Res. Lett. https://doi.org/10.1029/2020GL089093 (2020).

Polzin, K. L., Toole, J. M., Ledwell, J. R. & Schmitt, R. W. Spatial variability of turbulent mixing in the abyssal ocean. Science 276, 93–96 (1997).

Article  CAS  Google Scholar 

St Laurent, L. C. & Thurnherr, A. M. Intense mixing of lower thermocline water on the crest of the Mid-Atlantic Ridge. Nature 448, 680–683 (2007).

Article  Google Scholar 

Send, U., Kanzow, T., Zenk, W. & Rhein, M. Monitoring the Atlantic Meridional Overturning Circulation at 16° N. CLIVAR Exch. 7, 31–33 (2002).

Kanzow, T., Send, U. & McCartney, M. On the variability of the deep meridional transports in the tropical North Atlantic. Deep Sea Res. Part I 55, 1601–1623 (2008).

Article  Google Scholar 

Johns, W. E. et al. Variability of shallow and deep western boundary currents off the Bahamas during 2004–05: results from the 26° N RAPID–MOC array. J. Phys. Oceanogr. 38, 605–623 (2008).

Article  Google Scholar 

McCarthy, G. D. et al. Measuring the Atlantic Meridional Overturning Circulation at 26° N. Prog. Oceanogr. 130, 91–111 (2015).

Article  Google Scholar 

Meinen, C. S. et al. Variability of the Deep Western Boundary Current at 26.5° N during 2004–2009. Deep Sea Res. Part II 85, 154–168 (2013).

Article  Google Scholar 

Wong, A., Keeley, R., Carval, T. & the Argo Data Management Team Argo Quality Control Manual for CTD and Trajectory Data (Ifremer, 2023).

Locarnini, R. A. et al. World Ocean Atlas 2018, Vol. 1: Temperature NOAA Atlas NESDIS 81 (NOAA, 2018).

Zweng, M. M. et al. World Ocean Atlas 2018, Vol. 2: Salinity NOAA Atlas NESDIS 82 (NOAA, 2018).

GEBCO Compilation Group GBCO 2020 Grid (GEBCO, 2020).

McCartney, M. S., Bennett, S. L. & Woodgate-Jones, M. E. Eastward flow through the Mid-Atlantic Ridge at 11° N and its influence on the abyss of the eastern basin. J. Phys. Oceanogr. 21, 1089–1121 (1991).

Article  Google Scholar 

Gupta, M. M. Numerical methods and software (David Kahaner, Cleve Moler, and Stephen Nash). SIAM Rev. 33, 144–147 (1991).

Article  Google Scholar 

Johns, E., Watts, R. D. & Rossby, T. H. A test of geostrophy in the Gulf Stream. J. Geophys. Res. 94, 3211–3222 (1989).

Article  Google Scholar 

Danabasoglu, G. et al. Revisiting AMOC transport estimates from observations and models. Geophys. Res. Lett. https://doi.org/10.1029/2021GL093045 (2021).

Send, U., Lankhorst, M. & Kanzow, T. Observation of decadal change in the Atlantic meridional overturning circulation using 10 years of continuous transport data. Geophys. Res. Lett. https://doi.org/10.1029/2011GL049801 (2011).

Akima, H. A new method of interpolation and smooth curve fitting based on local procedures. J. ACM 17, 589–602 (1970).

Article  Google Scholar 

Bindoff, N. L. & Mcdougall, T. J. Diagnosing climate change and ocean ventilation using hydrographic data. J. Phys. Oceanogr. 24, 1137–1152 (1994).

Article  Google Scholar 

Häkkinen, S., Rhines, P. B. & Worthen, D. L. Heat content variability in the North Atlantic Ocean in ocean reanalyses. Geophys. Res. Lett. 42, 2901–2909 (2015).

Article  Google Scholar 

McDougall, T. J. & Barker, P. M. Getting Started with TEOS-10 and the Gibbs Seawater (GSW) Oceanographic Toolbox SCOR/IAPSO WG127 (Teos, 2011); http://www.teos-10.org/software.htm

Jackett, D. R. & McDougall, T. J. A neutral density variable for the world’s oceans. J. Phys. Oceanogr. 27, 237–263 (1997).

Article  Google Scholar 

Emery, W. J. & Thomson, R. E. Data Analysis Methods in Physical Oceanography 3rd edn (Elsevier, 2001).

Biló, T. C., Straneo, F., Holte, J. & Le Bras, I. A. A. Arrival of new great salinity anomaly weakens convection in the Irminger Sea. Geophys. Res. Lett. 49, e2022GL098857 (2022).

Article  Google Scholar 

Hussain, M. & Mahmud, I. pymannkendall: a Python package for non parametric Mann Kendall family of trend tests. J. Open Source Softw. https://doi.org/10.5281/zenodo.3347253 (2019).

Mann, H. Nonparametric tests against trend. Econometrica https://doi.org/10.2307/1907187 (1945).

Kendall, M. Rank Correlation Methods 4th edn (Charles Griffin, 1975).

Yue, S. & Wang, C. The Mann–Kendall test modified by effective sample size to detect trend in serially correlated hydrological series. Water Resour. Manage. 18, 201–218 (2004).

Article  Google Scholar 

Send, U. & Lankhorst, M. Meridional overturning variability experiment. Univ. California San Diego https://mooring.ucsd.edu/move/ (2024).

Kanzow, T., Carrilho Bilo, T., Lankhorst, M. & Mauritzen, C. Guyana Abyssal Gyre Experiment (GAGE) current meter mooring ocean velocity records obtained between February 2000 and April 2002 at 16° N. Univ. of Miami Libraries https://doi.org/10.17604/5jd9-7f77 (2023).

WOCE and GOSHIP. CLIVAR and Carbon Hydrographic Data Office https://cchdo.ucsd.edu/ (2023).

RAPID. National Oceanography Centre https://www.bodc.ac.uk/data/bodc_database/nodb/ (2024).

Fumihiko, A. et al. Argo float data and metadata from Global Data Assembly Centre (Argo GDAC). SEANOE https://doi.org/10.17882/42182 (2024).

WBTS. NOAA/OAR AOML https://www.aoml.noaa.gov/phod/wbts/data.php (2024).

WOA18. NCEI https://www.ncei.noaa.gov/data/oceans/woa/WOA18/DATA/ (2019).