{"id":448448,"date":"2026-06-04T07:56:54","date_gmt":"2026-06-04T14:56:54","guid":{"rendered":"https:\/\/climatescience.press\/?p=448448"},"modified":"2026-06-04T07:56:55","modified_gmt":"2026-06-04T14:56:55","slug":"the-co2-enigma-in-deep-ocean-currents","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=448448","title":{"rendered":"The CO2 Enigma in Deep Ocean Currents"},"content":{"rendered":"\n
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From The CO2 Coalition\u00b4s Substack<\/a><\/p>\n\n\n\n

By Ganapathy Shanmugam, Ph.D.<\/p>\n\n\n\n

CO2<\/sub> Coalition Substack. Submitted June 3, 2026. 16 p.<\/strong><\/p>\n\n\n\n

The CO2 Enigma in Deep Ocean Currents<\/strong><\/p>\n\n\n\n

Ganapathy Shanmugam, Ph.D.<\/strong><\/p>\n\n\n\n

Introduction<\/strong><\/p>\n\n\n\n

Deep Ocean Currents have been well documented in the World\u2019s Oceans ((Heezen, Hollister and Ruddiman, 1966; Hollister, 1967; Pequegnat et al. 1972; Shepard et al. 1979; Shanmugam, 2016, 2017, 2021). Although there are claims of impact of CO2 on deep ocean currents, there are no published empirical data on measurements of CO2 from specific Deep Ocean Currents, such as 1) Thermohaline Contour Currents, 2) Wind-Driven Bottom Currents, 3) Tidal Bottom Currents, and 4) Baroclinic Currents. The role of CO2 on Ocean Currents remains an enigma. The purpose of this note is to document this disconnect between the climate narrative on CO2 and the absence of empirical data on the concentration of measured CO2 in Ocean Currents.<\/p>\n\n\n\n

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Atmospheric and Oceanic CO2 Measurements<\/strong><\/p>\n\n\n\n

The Keeling Curve (Fig. 1A) is the gold standard of measurements of atmospheric CO2. In the atmosphere, CO2 is measured as ppm (parts per million). By contrast, CO2 is measured as fugacity in the Oceans (Fig. 1C). The release of Surface Ocean CO2<\/sub> Atlas (Mkitarian, 2024)<\/a> on June 19th<\/sup>, 2024 revealed that the number of oceanic measurements of the climate change-driving greenhouse gas, carbon dioxide (CO2<\/sub>), has continued to decrease, following a downward trend since 2018. The number of observations submitted to this annual update is as low as the more limited observing efforts from a decade ago, as seen in the graph below (Fig. 1C).<\/p>\n\n\n\n

It must be noted that the atmospheric 1 ppm CO\u2082<\/strong> is a mixing ratio<\/em> (a concentration) (Fig. 1A), while the oceanic 1×106<\/sup> fCO\u2082<\/strong> refers to the effective pressure<\/em> a real gas exerts when accounting for non\u2011ideal behavior (Fig. 1C). They measure fundamentally different things. Furthermore, these fugacity of CO2 values do not refer to CO2 in specific type of Ocean Currents.<\/p>\n\n\n\n

The Climate-Change Narrative<\/strong><\/p>\n\n\n\n

The thermohaline circulation is central to why the deep ocean is Earth\u2019s largest long\u2014term carbon reservoir. Cold, dense waters at high latitudes sink and carry dissolved gases\u2014including CO\u2082 and O\u2082\u2014into the abyss, where they remain isolated from the atmosphere for centuries to millennia. This slow overturning effectively stores atmospheric carbon in the deep ocean. There are published articles that discuss \u201cShifting winter atmospheric teleconnections to the North Pacific\u2026\u201d (Anderson et al., 2026). Their study shows how freshwater influx into the North Atlantic\u2014a process intensified under CO\u2082\u2011driven warming\u2014weakens the Gulf Stream and broader Atlantic Meridional Overturning Circulation (AMOC). It also demonstrates how these circulation changes propagate climate effects as far as Alaska through teleconnections. However, there are no quantitative studies on the impact of CO2 on the behavior of Ocean Currents. In a climate narrative, for example:<\/p>\n\n\n\n

Bauer (2019) in an article entitled \u201cClimate Change is weakening the Ocean\u2019s Currents. Here\u2019s why that matters\u201d states that \u201cLikewise, in modern-day oceans, the thermohaline circulation mixes dissolved gases (such as carbon dioxide and oxygen) into the deep ocean. This means that the oceans are able to draw down and store more carbon dioxide from the atmosphere. The deep ocean is the largest reservoir (or storage) for carbon dioxide on Earth. If circulation slows due to warming waters, the churning of the carbon dioxide will slow, which will keep more carbon dioxide in our surface waters and atmosphere. This can lead to increasing ocean acidification, which is very harmful to marine life.\u201d<\/p>\n\n\n\n

Mkitarian (2024) notes that \u201cThe annual release of the SOCAT data product is crucial to quantifying ocean CO2<\/sub> uptake \u2013 a critical ecosystem service that naturally removes ~25% of anthropogenic CO2<\/sub> from the atmosphere, offsetting the impacts of climate change caused by human-produced greenhouse gases. This absorption of CO2<\/sub> by the ocean means that relatively less carbon ends up in the atmosphere, reducing the greenhouse gas \u201cblanket\u201d that surrounds and warms the planet. While this ability of the ocean to act like a carbon-absorbing sponge is critical, it still has negative consequences, like ocean acidification<\/a>, which can impact marine life and the people who depend on it.\u201d<\/p>\n\n\n\n

According to NOAA (2026), the ocean absorbs about 30% of the carbon dioxide (CO2<\/sub>) that is released in the atmosphere. As levels of atmospheric CO2<\/sub> increase from human activity such as burning fossil fuels (e.g., car emissions) and changing land use (e.g., deforestation), the amount of carbon dioxide absorbed by the ocean also increases. When CO2<\/sub> is absorbed by seawater, a series of chemical reactions occur resulting in the increased concentration of hydrogen ions. This process has far reaching implications for the ocean and the creatures that live there. But there are no studies of how ocean acidification affects Ocean Currents.<\/p>\n\n\n\n

Four Types of Ocean Currents<\/strong><\/p>\n\n\n\n

In an oceanographic context, global circulation of water masses were discussed by Talley (2013) (Fig. 2). In a comprehensive review, Shanmugam (2008) identified four types of bottom currents in the world\u2019s Oceans, namely (1) Thermohaline-Driven Geostrophic Contour currents, (2) Wind-Driven Bottom Currents, (3) Tide-Driven Bottom Currents, and (4) Internal wave\/tide-driven baroclinic currents.<\/a><\/p>\n\n\n\n

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1. Thermohaline-Driven Geostrophic Contour currents<\/strong><\/p>\n\n\n\n

In the Atlantic, geostrophic thermohaline contour currents were discussed by Heezen et al. (1966) and by Hollister (1967) (Fig. 3A). The Antarctic Bottom Water (AABW) develops as downslope gravity flows (Fig. 4), but turns into a Contour current with a distinct bottom current layer (Fig. 5). To date, there are no measured CO2 content in the bottom current layers of thermohaline contour currents.<\/p>\n\n\n

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2. Wind-Driven Bottom Currents<\/strong><\/p>\n\n\n\n

The Pliocene-Pleistocene sequence cored in the Ewing Bank Block 826 field in the Gulf of Mexico (Fig. 6) provides an example of sand distribution and reservoir quality of deep-marine bottom-current reworked sands (Shanmugam et al. 1993). Presumably, the Loop Current (Fig. 7), a strong wind-driven surface current in the Gulf of Mexico, impinged on the sea bottom, as it does today, and resulted in bottom-current reworked sands (Fig. 8). To date, there are no measured CO2 content in wind-driven bottom currents with complex hybrid flows (Fig. 9).<\/p>\n\n\n

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3. Tide-Driven Bottom Currents<\/strong><\/p>\n\n\n\n

Submarine canyons provide a unique setting for tidal processes to operate from shallow-marine to deep-marine environments. In modern canyons, current-meter measurements at varying water depths (46\u20134200 m) show a close correlation between the timing of up- and down-canyon currents and the timing of semi-diurnal tides (Shepard et al. 1979; Shanmugam, 2003)). These tidal bottom currents in submarine canyons commonly attain maximum velocities of 25\u201350 cm\/s (Fig. 10). To date, there are no measured CO2 content in tidal bottom currents in submarine canyons.<\/p>\n\n\n

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4. Internal wave\/tide-driven Baroclinic Currents<\/strong><\/p>\n\n\n\n

In a comprehensive review, Shanmugam (2013) discussed oceanographic aspects of baroclinic currents (Figs. 11 to 15). Internal waves are gravity waves that oscillate along oceanic pycnoclines. Internal tides are internal waves with a tidal frequency. Internal solitary waves (i.e., solitons), the most common type, are commonly generated near the shelf edge (100\u2013200 m [328\u2013656 ft] in bathymetry) and in the deep ocean over areas of sea-floor irregularities, such as mid-ocean ridges, seamounts, and guyots. Empirical data from 51 locations in the Atlantic, Pacific, Indian, Arctic, and Antarctic oceans reveal that internal solitary waves travel in packets. Internal waves commonly exhibit (1) higher wave amplitudes (5\u201350 m [16\u2013164 ft]) than surface waves (<2 m [6.56 ft]), (2) longer wavelengths (0.5\u201315 km [0.31\u20139 mi]) than surface waves (100 m [328 ft]), (3) longer wave periods (5\u201350 min) than surface waves (9\u201310 s), and (4) higher wave speeds (0.5\u20132 m s\u20131<\/sup> [1.64\u20136.56 ft s\u20131<\/sup>]) than surface waves (25 cm s\u20131<\/sup> [10 in. s\u20131<\/sup>]). Maximum speeds of 48 cm s\u20131<\/sup> (19 in. s\u20131<\/sup>) for baroclinic currents were measured on guyots. However, core-based sedimentologic studies of modern sediments emplaced by baroclinic currents on continental slopes, in submarine canyons, and on submarine guyots are lacking. No cogent sedimentologic or seismic criteria exist for distinguishing ancient counterparts. To date, there are no measured CO2 content in baroclinic currents in the world\u2019s oceans.<\/p>\n\n\n

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Concluding Remarks<\/strong><\/p>\n\n\n\n

Although there are four major types of Ocean Currents (Fig. 16), there are no measured concentration values of CO2 from individual types of Ocean Currents.<\/p>\n\n\n\n

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Atmospheric CO2 is measured in ppm, whereas Oceanographic CO2 is measured in fugacity. The fundamental values of ppm and fugacity are not comparable for the following reasons:<\/p>\n\n\n\n

1 ppm of CO\u2082 in the Atmosphere represents<\/strong><\/p>\n\n\n\n

\u00b7 A composition<\/em> of a gas mixture.<\/p>\n\n\n\n

\u00b7 A dimensionless number.<\/p>\n\n\n\n

\u00b7 Independent of pressure.<\/p>\n\n\n\n

\u00b7 Used in atmospheric science and gas sensors.<\/p>\n\n\n\n

1×106<\/sup> fCO\u2082<\/strong> in the Oceans represents<\/strong><\/p>\n\n\n\n

\u00b7 A thermodynamic activity.<\/em><\/p>\n\n\n\n

\u00b7 Has units of pressure (atm, bar, Pa).<\/p>\n\n\n\n

\u00b7 Depends on non\u2011ideal gas behavior.<\/p>\n\n\n\n

\u00b7 Used in chemical equilibrium, solubility, and high\u2014pressure systems.<\/p>\n\n\n\n

There is no direct conversion<\/strong> between \u201c1 ppm\u201d and \u201c1 fugacity\u201d because one is a ratio and the other is an effective pressure.<\/p>\n\n\n\n

Various problematic aspects of Climate Change are discussed in great detail elsewhere (Shanmugam, 2023, 2024a and b, 2025, 2026).<\/p>\n\n\n\n

Acknowledgements<\/strong><\/p>\n\n\n\n

I thank Angela Wheeler, Executive Director of the CO2<\/sub> Coalition, for inviting me to submit this article. I am grateful to Jean Shanmugam for her comments.<\/p>\n\n\n\n

References<\/strong><\/p>\n\n\n\n

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Anderson, L., Finney, B.P. & Baxter, W.B. 2026. Shifting winter atmospheric teleconnections to the North Pacific reconcile Younger-Dryas and Holocene \u03b418<\/sup>O signals. Nat Commun<\/em> 17, 2287 (2026). https:\/\/doi.org\/10.1038\/s41467-026-68841-2<\/a><\/p>\n\n\n\n

Bauer, J. 2019. Climate Change is weakening the Ocean\u2019s Currents. Here\u2019s why that matters. UF Thompson Earth Systems Institute. University of Florida. Gainesville, Florida. https:\/\/www.floridamuseum.ufl.edu\/earth-systems\/blog\/climate-change-is-weakening-the-oceans-currents-heres-why-that-matters\/<\/a><\/p>\n<\/blockquote>\n\n\n\n

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