Thanks, so that's 2.5% of 0.04%, right?

Has it been proven that a gas comprising 0.04% of Earth's atmosphere is the main factor which affects Earth's climate(s)?

I'm asking, because 0.04% of something seems like a particularly small fraction to have such a dramatic effect on a whole planet's weather and climate. Especially in a non-linear dynamic and chaotic - hence very difficult to predict - system like Earth's weather and climate system.

In my opinion it is important to ask these questions because some extremely huge decisions ride on them.

The fact that a small proportion of the atmosphere causes the greenhouse effect makes it more likely that the amount of CO2 we are adding is affecting the planet. It's easier to make a significant change in a smaller quantity.

If you have doubts about the scientific understanding of the greenhouse effect, study up on that. But continually bringing up that 0.04% makes it sound like you are clinging to that fact as a "gotcha" and avoiding learning anything more.

>If you have doubts about the scientific understanding of the greenhouse effect, study up on that. But continually bringing up that 0.04% makes it sound like you are clinging to that fact as a "gotcha" and avoiding learning anything more.

After having spent decades debating "climate change deniers", I came to to the realization that the greenhouse effect as thought in schools is vastly oversimplified, and essentially no lay person understands it.

This is not to say that climate change isn't real, but most people don't have the technical background to educate each other, and attempt to do so based on inaccurate models.

Having read hundreds of articles, I still don't understand how to reconcile the greenhouse model with the fact that infrared radiation only travels ~10m in the atmosphere in the bandwidth absorbed by CO2.

> Especially in a non-linear dynamic and chaotic - hence very difficult to predict - system like Earth's weather and climate system.

It's because it's a highly non-linear and chaotic system.

If earth's climate was a linear system, then indeed your gut feeling that 0.04% change is small would be warranted.

Natural emissions are balanced by natural sinks, so that the balance is close to zero, while human emissions are not balanced by anything. The actual variation of CO2 levels in the atmosphere is almost exclusively due to human emissions tipping the equilibrium.

The effect of CO2 on the climate is old science, it goes back to the 19th century, it seems a little bit insincere to ask this kind of question, if you had actual interest you would have found the answer very easily already.

> main factor which affects Earth's climate

This is such a dubious statement you keep repeating. Is it the main one? No, probably not. If you took out all the Nitrogen, shit would break a lot faster than if you took out all the CO2. You could probably name a few others.

However it is proven that carbon emissions is the main thing affecting the the change we are observing in earth's climate. And I shouldn't have to, because you are who you are, I'm going to staple on "within reasonable amount of certainty"

Water vapor is the #1 greenhouse gas but that is a closed system. We aren’t making (much) more water.

Now, we could potentially make many more clouds. For instance, container ships could be required to have fuel additives or “salt lofters”that promote cloud seeding and marine cloud brightening.

We aren't directly putting more water vapor into the atmosphere, but a warmer atmosphere can hold more water and (I would think) would also increase the overall rate of evaporation.

Regarding the greenhouse effect of water vapor, I don't know whether what matters is the average relative humidity or the total amount of water vapor in the atmosphere. For our sake I hope it's the former.