What happens when one tries to work out a science problem when one does not know the math?

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The problem is not only whether or not you can 'do the math' but whether you have the correct mathematical model. Only working with CO2 means that this model is too simple. At the very least methane must also be included. A good model would consider all known greenhouse gases....Show more

<<What I was claiming was that if CO2 started dropping, the second derivative of temperature with respect to time would be negative (it actually could be negative even other conditions) but that the derivative of temperature with respect to time would remain positive at first.>>

To be fair to Trevor, he did say the exact same thing. Check out his fourth paragraph. The whole discussion became bogged down with the tree issue, which seemed rather tangential to me, so I can see it'd be easy to miss, but a more careful reading would prevent these sorts of silly questions in the future.

There is no doubt that, fundamentally, the problem Dook poses -- the issue of the time lag -- requires differential equations to answer, and the exact value would depend on dCO2/dt and the complexity of your model. I don't think it would be too difficult to work out a crude approximation using something like a simple box model (which, of course, involves a system of differential equations). I'm not sure it would provide much illumination to a majority of posters here, which is why a more qualitative answer generally suffices, but I agree that it is disingenuous of Trevor to imply that the problem -- which, ultimately, he didn't really address -- can be solved without DEs.

Dook
<<I didn't ask about temperature lags, only about water vapor feedback lags, so your answer should preferably focus on the latter.>>

Given that the WV feedback is a function of temperature, they are the same question. In fact, we don't need *any* information about the feedback itself (e.g. Clausius-Clapeyron), other than the mere fact that it responds to temperature, to answer your question....Show more

"...what will happen is not that the temperature will immmediately drop as Trevor and his spreadsheet claim.."

That's not what he said, what he said was: "the cooling effect would be immediate" which is consistent with your statement: "but rather that *the rate of increase* in the temperature will drop."

As per a dictionary definition of "cooling": 1. Become or cause to become less hot.

I.e., if you reduce CO2, a drop in the rate of increase in the temperature would be immediate. It might be small and the warming will continue for quite some time, but by definition it will be cooling and the effect will be immediate.

What you are saying is the temperature will not immediately have rate of *decrease* which is also correct.
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Edit: "What I was claiming was that if CO2 started dropping, the second derivative of temperature with respect to time would be negative..."

Again, this meets the definition of an immediate cooling effect. You might want to give a reference to exactly what Trevor said but I see nowhere where he said temperatures (first derivative) would immediately start dropping. And you appear to agree: "He of course did not use that wording"

I can't really see any point you are making here; well one that is clear anyways....Show more

Well, part of what happens when you try to do science without knowing the math depends on the degree of precision you are 1. aiming for, and 2. claiming.

I do not know the magnitude, or the mathematics, of the albedo feedback. But I know that there is one, so I also know that efforts to paint white areas that were until recently covered by glaciers are likely to slow warming at least slightly. And thus, by a reasonable definition of the term, have a cooling effect.

And I do not need to know any of the math, really, to know that if you remove CO2 from the air, the Earth will very shortly end up cooler than it would have been if you did not remove that CO2.

I think this may be another case where you are primarily nitpicking someone's word choice. A cooling effect does not necessarily mean that temperatures will drop from what they were before... just that they will drop from what they otherwise would have been. And you agree that this is, in fact, the case.

edit:
I would like to note that "it will cause a cooling effect" is *not* the same as "it will cause cooling". And I think most people even tangentially related to the relevant sciences will understand the difference....Show more

Trevor is right, you are wrong. The reason you are wrong is that you are using the analogy that CO2 is a thermostat and there is some sort of thermal lag in climate like there would be in a house. However, you are mistaken in that assumption. In fact, a thermostat controls the energy input to the house (the furnace). Shut off the furnace (i.e., the energy input into the house) and the house starts to cool immediately. In climate, CO2 is the furnace. Reduce CO2, and the cooling begins immediately. The thermostats in climate are the feedbacks and heat sinks like the ocean and cryosphere. But regardless of how big those are, if you shut off the furnace, the house cools.

Now, go apologize to Trevor. There's a luv....Show more