I mean, informally if a carbon sink responds to more CO2 by increasing absorption, it’s a “feedback” in layman’s terms, but I don’t think scientists use the word that way.
By the way, the word “feedbacks” is usually not normally used to refer to carbon sinks.
David Piepgrass

And that’s a gap in the models. If your models cannot account for terrestrial sinks and sources that dynamically react to changes in CO2, you’ll never be able to make decent predictions.

This can be explained as increased uptake by the ocean and by vegetation.

Okay, imagine for example you’ve just identified the mechanism — plant life and the oceans actually drive atmospheric CO2 concentrations dynamically, based on temperature. Regardless of our human activity (or the activity of butterflies, or voles, or any other life form that generates CO2 as part of its life), nature will compensate for it. If CO2 is added, plant life grows to pick up the slack. If CO2 is removed, plant life dies and doesn’t absorb as much.

Now, instead of just requiring an atmospheric model, you need to include biology, and liquid dynamics.

I believe it’s driven by the laws of physics; I don’t follow your abstraction. Shouldn’t the laws of physics be the basis for analysis?

We saw from our metal bar in a hot bucket of water that biology qualitatively changes things. Of course you can see chemistry as merely complex physics, and biology as merely complex chemistry, but you do yourself a disfavor when you stop at physics, and don’t consider the complexity of chemistry and biology.

If you’re trying to say that carbon sinks respond in a nonconstant or nonlinear way to increased CO2 concentrations, I think that climate scientists would agree with you — but would say that the nonlinearity is not that strong.

Here’s the tricky part — what if they also respond in a nonconstant and nonlinear way to decreased CO2 concentrations?

An additional hose won’t open the drain “magically”. There must be some physical mechanism.

Of course. But if we don’t know what the exact mechanism is, it will seem like magic at least in the context of the preconceptions that we came to the problem with.

Likewise, to expect the CO2 will “drain out” requires some physical mechanism in the natural environment that would dramatically increase CO2 absorption.

You’ve already mentioned plants and oceans, so I think you’re at least recognizing that there do exist these dynamic, reactive mechanisms that are driven by more than basic thermodynamic equations, and are comprised of complex chemistry and biology.

In contrast, after studying climate science for hundreds of hours now, it is not at all obvious that there could be a large unexpected increase in CO2 absorption.

Are you feeling a bit of cognitive dissonance? You’ve already admitted that the uptake of the oceans and vegetation was unexpected (unless you have a citation that predicted that oceans and vegetation would dynamically respond to increased emissions, rather than simply respond linearly).

I don’t think it’s likely that they all missed some big elephant in the room.

I think the problem is that they can’t imagine that a bunch of little invisible bacteria all around the room could do something significant. If all you can think of that could make a difference is an elephant, when you don’t find one, you’ll feel unjustified confidence. Keeping your mind open to the unknown unknowns is really hard.

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