Abstract:  CO₂ flux shifts from absorption to emission as sea surface temperature (SST) rises, with a ~4% decrease in absorption per °C.

Objective:
Quantify CO₂ and water vapor fluxes as a function of SST in a controlled ocean-like system.

Setup:
Apparatus: A temperature-controlled seawater tank (e.g., 100 L) equipped with a gas analyzer (e.g., an Agilent GC/MS, or a LI-COR LI-850 for CO₂) and humidity sensor (e.g., Vaisala HMP60). Use a heat exchanger to vary water temperature (15°C to 30°C) and a fan to simulate wind-driven turbulence.

Procedure:

1. Fill the tank with seawater (salinity ~35 psu to represent typical ocean salinity) and equilibrate with ambient air (CO₂ ~420 ppm).
2. Measure initial CO₂ concentration in water (C_w) using titration or a pCO₂ sensor and atmospheric CO₂ (C_a).
3. Incrementally increase SST by 1°C intervals, maintaining constant wind speed (e.g., 5 m/s).
4. Record CO₂ flux using the gas analyzer and water vapor flux via humidity changes over 30-minute intervals at each temperature.
5. Calculate k_w using empirical models (e.g., Wanninkhof, 2014: k_w = 0.251 * u² * (Sc / 660)^(-0.5), where u is wind speed and Sc is the Schmidt number, temperature-dependent). [The Schmidt number (Sc) is a dimensionless parameter in fluid dynamics and mass transfer, defined as the ratio of kinematic viscosity (ν) to mass diffusivity (D):
   Sc = ν / D  It characterizes the relative thickness of the momentum boundary layer to the concentration boundary layer, indicating the relative rates of momentum and mass diffusion. Sc is temperature-dependent because both ν (via dynamic viscosity μ and density ρ) and D increase with temperature, typically causing Sc to decrease (e.g., for CO₂ in seawater, Sc ≈ 660 at 20°C but drops significantly at higher temperatures due to faster D growth, at least this I what I have read so far].

Data Analysis:
• Plot CO₂ flux (F_CO2) and water vapor flux vs. SST.  (This is flux as in Fick’s Law not flow rate.)
• Fit data to the flux equation and Clausius-Clapeyron relation to derive ∂F / ∂T.  (Note partial derivatives.)
• Estimate rate of change by correlating flux changes with dT / dt (e.g., 0.1°C/day).

Expected Results:
• CO₂ flux shifts from absorption to emission as SST rises, with a ~4% decrease in absorption per °C.
• Water vapor flux increases exponentially, roughly doubling from 15°C to 30°C. This experiment provides empirical data to validate theoretical models and quantify SST-driven changes in gas and vapor fluxes, relevant to climate modeling.

Sources:

Grok (xAI). (2025). Conversations with Grok [Large language model]. xAI. Retrieved September 8, 2025, from https://grok.com

Wanninkhof, R. (1992) Relationship between wind speed and gas exchange over the ocean. Journal of Geophysical Research:Oceans. 95(C5) pages 7373-7382. https://doi.org/10.1029/92JC00188

Wanninkhof, R. (2014) Relationship between wind speed and gas exchange (revisited). Journal of Geophysical Research: Oceans, 119(5), pages 1851–1866. https://doi.org/10.4319/lom.2014.12.351

First thought experiment on CO2 with Grok:

PS:  See Bob Weber’s work.  You may want to follow Bob relating especially to SST varying by surface area.  bob@electricweather.com

PSS:  In the experiment above, the biological content in the tank of natural seawater could also be varied by quantity, species, and growth state. Varying wind speed or currents in water also possible.  In another variation, temperature change of the surface thin layer due to changes in CO2 partial pressure or concentration in the headspace could also be monitored.

PSSS: This thought experiment is not quite ready for prime time.  I need to investigate regarding the need to temperature weight geographic surface areas (cells) by a method to be determined, as implied by the works of Bob Weber.  For example, square miles per day of surface at 25 C versus square miles per day of surface at 26 C would have different net flux of CO2. Some literature suggests this area delta T is already compensated. It may be necessary to add to this experiment an IR pyrometer for precisely measuring the macroscopically thin surface skin T (vs. a bulk probe T which includes the well mixed layer below the thin layer surface).  Insolation (e.g., via lamps) at low fan speeds can mimic, and fit ∂F/∂T. Maybe some form of a T⁴ term in the energy balance to compensate for insolation at the surface, like for Q_net → SST evolution analogous to thermodynamics.  [Stefan-Boltzmann law states that the energy radiated by a blackbody is proportional to the fourth power of its absolute temperature.] So far I do not see how a vertical temperature gradient across ocean thin layer compensates for either a horizontal or a earth curved gradient across surface geographical cells with regard to net flux of CO2 from/to the surface.  If you have pertinent references, please comment of advise. Climate orthodoxy going back to Bert Bolin, the first head of IPCC, in his 1960’s era papers ignores surface area, and AI engines today continue his narrative, which led to his error that ocean does not have enough chemical capacity to absorb human-produced CO2 emissions. He concluded that human-produced CO2 emissions were causing the slope of the Keeling Curve. Fick’s Law defines net flux as dependent on surface area and well as gradient across a thickness of surface and the diffusion constant. We showed in Bromley & Tamarkin (2022) that ocean has demonstrated far more chemical capacity than needed to absorb and then re-emit human-produced-CO2 in addition to naturally produced CO2.