Carbon Feedback Loop

I am not a science person I have just been doing some reading and have some questions about the carbon feedback loop. I don’t want to make this political as my question is very specific. Looking for scientific answers.
My perception based on what I have read is that co2 will cause a slight temperature rise in the atmosphere creating more water vapor which is a powerful greenhouse gas. The more water vapor will create even more heat evaporating more water and the cycle continues. As far as I know water vapor is very predictable in that it will change to a liquid at very specific temperature and densities. It would seem that any excess energy being stored in our lower atmosphere would be used to lift water into the upper atmosphere and the energy would come back down as impact on the ocean or land. Wouldn’t this be some kind of temperature regulator. Wouldn’t this prevent temperature rises more than just a couple of degrees? If that? Why would the feedback loop happen with carbon? Why does it not happen with water vaper alone?

According to this, water vapor is self-limiting, since when it gets too abundant, it rains down, like you say.

CO2 doesn’t condense into water like water vapor does, so it continues to trap heat, which continues to warm the planet. Just a few degrees will lead to giant changes on the planet.

So, as we add more CO2, it just sticks around, trapping more and more heat.

Yes, that was my first impression, but my point is doesn’t water vapor remove that trapped heat in the form of vapors and rain, converting the energy.

To me it would seem logical that the only temp rise would be the very short term temp rise of trapped heat. It would only be accumulating for a very short period of time.

I mean, yes? If it weren’t for increasing carbon, then the temperature would be relatively stable. I’m not sure what you’re asking – temperatures were relatively stable for tens of thousands of years as water vapor trapped head and some radiated out. Then, humans started adding lots of CO2 into the atmosphere and now the temperature is increasing.

Where do you think the water vapor is storing the excess heat trapped by the CO2??

If you agree that the temperature was relatively stable, and we had around the same amount of water vapor, and then we trap a lot more heat because of the CO2 in the atmosphere, why would you expect it to remain stable?

Water vapor behaves very predictably how it behaves will not change. Heat or excess heat will expend its energy lifting water vapor high into the clouds and beyond. When the temperature and moisture levels reach very specific points the raindrops will fall, converting heat energy into impact energy. This would limit any temperature rises and negate and feedback loop. If feedback loop was even possible it would be far more likely that the water vapor would be the big driver of this in response to solar changes.

Where is it dumping the excess heat that the CO2 is trapping?

Do you agree that we’ve already seen warming at least? Look at the bottom of this graph to see the warming as of a few years ago (bottom of the giant comic).

The question is very specific about the carbon loop.

What does water vapor have to do with a carbon loop? I’m not even sure what carbon loop you’re talking about.

Why did you respond??

Which converts back to heat once it impacts.

Fair enough. Good luck!

Good point, that is one of the things I hope to see addressed here.

An important effect is that we expect to see more cloud coverage with higher water vapor content in the air. This would have a general effect of raising Earth’s albedo and reflecting away more sunlight, cooling the Earth.

However, much depends on where the clouds form. Not just geographically, but in terms of altitude. And this is one of the least understood areas of climate change.

Another possible effect is that the water will precipitate out at the poles, increasing the size of the ice caps or at least lowering the rate of decrease. This also affects Earth’s albedo. But this isn’t certain either, as the atmosphere is complex and changes are very hard to predict.

There are many feedbacks in the climate system, both positive and negative. Many we know about, even more are probably still mysteries. This is common to complex systems. Trying to figure out which ones will dominate the future climate is not easy.

You’re complicating your mental model of water vapor feedback with a bunch of extraneous factors that make little or no difference to the basic warming process. Here’s the simple and scientifically correct model.

CO2 and other greenhouse gases like methane are called climate forcings because they independently drive planetary warming; they don’t arise as the effect of something else. Water vapor, OTOH, is a feedback for the simple reason that the absolute amount of water vapor in the atmosphere is a direct function of temperature. Relative humidity tends to stay fairly constant, but the absolute humidity – the absolute amount of water vapor in the atmosphere – rises with temperature. So as CO2 warms the planet, the amount of water vapor in the atmosphere rises, acting as a feedback that approximately doubles the effect of increasing CO2.

Energy transfers due to things like evaporative cooling or its opposite, the heat released on condensation, are irrelevant because they balance out. The only thing that matters is that water vapor in the atmosphere acts like a potent greenhouse gas, although it’s important to always keep in mind that it comes into being as a feedback, not an independent forcing.

The remaining question is why water vapor doesn’t create runaway feedback – more water vapor = more heating = more water vapor and so on indefinitely. The reason lies in the fact that the earth also cools due to infrared radiation to space. This outgoing blackbody radiation per unit of temperature rise quickly outpaces the rate at which the water vapor contributes to warming. In fact the radiative flux to space per unit temperature rise is about twice that of water vapor feedback warming, and this is what prevents runaway feedback.

No, we don’t really expect that, although as you say it’s a complicated question. In addition, high cirrus clouds actually contribute to warming by predominantly reflecting IR back down to earth, and it’s the low clouds that create cooling albedo on balance. In fact Lindzen once proposed a theory, now mostly discredited, that increased tropical sea surface temperatures would reduce cirrus cloud formation and have a cooling effect by increasing radiative flux to space. In any case, I don’t believe there is any sort of consensus at all on the whole question of cloud formation, although the IPCC Fifth Assessment report stated the belief that cloud feedbacks on long-term greenhouse-gas induced surface temperature change are likely positive.

This is one of the major things I have been wondering about. Does this work according to any law of physics that makes it predictable and consistent?

Water vapor in the atmosphere regularly increases, locally, to saturation and condenses out. So the vapor content has a limit.

But the energy moved around by vapor between land, ocean and atmosphere doesn’t transport much heat out of the Earth system. The condensing water heats up the local atmosphere. Very little of its heat is radiated out.

CO2 on the other hand is very far from saturation. We could have much, much higher CO2 levels.

Yes, in isolation, but it’s part of a system with many interacting parts, which is why predicting the Earth’s future temperature requires complex models.

Well, as @naita said, it’s not so much a single law of physics but a whole bunch of interacting parts that are collectively referred to as the earth’s energy budget within which many specific laws and principles can be found.