If we are referring to ocean surface skin temperature, then yes it's measured by satellites, but any claim that an observed change is specifically due to back radiation (downwelling longwave from greenhouse gases) is an attribution step that depends on models, not a direct measurement of that causal component. The ~3 W/m² figure from Happer and van Wijngaarden (and the conventional ~3.7 W/m² value used in most assessments) is a calculated radiative forcing, not a quantity that will be measured directly as an isolated CO2 delta. We also would not be able to distinguish whether or not the additional changes were due to CO2 edge band increases or water vapor. Again, this figure assumes WV will increase by 1% per decade. So, in reality, doubling is exaggerated by both skeptics and "believers". For years, I would try to explain this, and people here would continue to confuse everything, trying to plug in algorithms in, not realizing that this is not a physics problem were the values remain consistent. All natural systems resist change and the earth pushes back for every change made. In chemistry pH resists change. A warmer surface emits more longwave radiation (the Planck response). Happer and van Wijngaarden emphasize the same point when they note that a ~3 W/m² clear-sky reduction in flux to space from doubled CO2 is only about 1% of the total outgoing longwave radiation, and that small changes in cloud cover or altitude can compensate for it. The system does not simply retain the extra energy because we can do math; temperature, water vapor, clouds, and circulation adjust until the top-of-atmosphere budget is restored. Or as I said, it pushes back in the Le Chatelier’s principle (Henri Louis Le Chatelier, 1884): "If the equilibrium of a system is disturbed by a change in one or more of the determining factors (as temperature, pressure, or concentration) the system tends to adjust itself to a new equilibrium by counteracting as far as possible the effect of the change.”

"CO2 is a greenhouse gas - so ..." Sure, temperatures CO2 are related. But his relationship is backwards. The cart does not pull the horse. Anyone who has been married understands relationships are never simple. In the ice-core record, CO2 consistently lags Antarctic temperature during glacial-interglacial transitions, typically by centuries. Orbital (Milankovitch) changes initiate the warming; the oceans then outgas CO2 as a positive feedback. Newer analyses have narrowed the lag in some intervals, but they have not reversed the order. CO2 does not start the warming, it is the cart being pulled by the horse (Sun). If radiative forcing from CO2 is logarithmic. Each successive doubling produces less additional forcing (~3.7–4 W/m²), and would not be a linear increase. The main absorption bands are already heavily saturated near the surface. He continues to claim that we observe warming due to the presence of a signal, but that's dumb as we only see it in the presence of water vapor. Water vapor, not CO2, accounts for the large majority of the greenhouse effect. The uncertain quantity is climate sensitivity. And this is the real discussion. Is there really even any sensitivity? Observational energy-budget estimates for the modern period fall in the lower half of the model range (roughly 1.5–2.5 °C for a doubling in several studies), while many climate models run higher. This is an indication that sensitivity is low. This becomes a problem and it's the one every activist I see fails to acknowledge. The biggest reason is the recent rise in Earth’s energy imbalance (CERES era) has been driven primarily (or possibly entirely) by increased absorbed solar radiation (reduced albedo from clouds, aerosols, and sea ice), only partially offset by higher outgoing longwave radiation. OLR has not fallen. Yet, OLR not falling does not mean there has been no change in net heat flux. CERES data show that Earth’s energy imbalance (EEI = absorbed solar radiation minus OLR) has roughly doubled since the early 2000s, from about 0.5 W/m² to around 1.0–1.25 W/m² in recent multi-year averages, but as indicated above, it was NOT due to increased CO2. That's a pretty significant change which can't be attributed to CO2. A pure greenhouse-gas trapping signal would reduce OLR and thereby increase the imbalance. That is not what the satellite record shows over this interval. The longwave term has moved in the opposite direction; the shortwave term has driven the increase in net heat gain.

James has me blocked, so I will answer and you can re-share it to him, since he refuses to have an actual conversation with a real scientist. "Ground stations measure the downwelling IR radiation from the greenhouse effect every day. Satellites measure the upwelling IR radiation from the greenhouse effect every day." - James William Owens @Willard1951 We measure thermal radiation, and DO NOT isolate or quantify the incremental CO₂ greenhouse effect in the way his statement implies. Ground stations (pyrgeometers in networks like BSRN and SURFRAD) measure downwelling longwave radiation. Under clear skies, most of that radiation originates in the lowest few hundred meters of the atmosphere and is dominated by water vapor (WV), not CO₂. And, more than half typically comes from the bottom 100 m (aka WV). CO₂’s 15 µm band is already heavily saturated near the surface, so additional CO₂ adds little to no extra downwelling flux there. Observed rises in downwelling longwave are a mixture of higher air temperature, more water vapor, clouds, and a smaller direct greenhouse-gas contributions. There are also significant instrument calibration differences of several W/m². Satellites (CERES and others) measure outgoing longwave radiation (OLR) at the top of the atmosphere (TOA). Over the CERES record, OLR has increased, not decreased. Meaning, more of the sun's energy is getting absorbed and leaving the atmosphere. The rise in Earth’s energy imbalance since ~2000 has been driven primarily by increased absorbed solar radiation (lower albedo from clouds, aerosols, and sea ice), only partially offset by higher OLR. In a pure “more greenhouse gases trap more heat” picture without feedbacks, one would expect OLR to fall. The observations show the opposite net behavior once the system warms. Both sets of instruments confirm that the atmosphere is not transparent in the infrared and that it radiates according to its temperature and composition. That is NOT an indication that man is somehow making the skies and oceans warmer. That has been known for a long time and is not in dispute. But the important note here is that it DOES NOT demonstrate that the recent energy imbalance is dominated by CO₂ radiative forcing, nor do they isolate CO₂’s contribution from water vapor, clouds, or albedo changes. Those distinctions require magical thermodynamic models and attribution studies, not the raw flux measurements themselves. As usual James, simply makes claims that support his delusional beliefs without fact-checking the statement or qualifying it with scientific facts.