Clouding the issue

From Skeptical Science:

When skeptics use this argument [that water vapour is the strongest greenhouse gas], they are trying to imply that an increase in CO2 isn’t a major problem. If CO2 isn’t as powerful as water vapor, which there’s already a lot of, adding a little more CO2 couldn’t be that bad, right? What this argument misses is the fact that water vapor creates what scientists call a ‘positive feedback loop’ in the atmosphere — making any temperature changes larger than they would be otherwise.

How much does water vapor amplify CO2 warming? Studies show that water vapor feedback roughly doubles the amount of warming caused by CO2. So if there is a 1°C change caused by CO2, the water vapor will cause the temperature to go up another 1°C. When other feedback loops are included, the total warming from a potential 1°C change caused by CO2 is, in reality, as much as 3°C.

From The Conversation:

Global warming is expected to cause changes in the amount of cloud cover, and the height and thickness of these clouds in the future, shifting the balance between the parasol and blanket effects of clouds. The knock-on effect this will have on temperature is known as cloud feedback. Climate change projections cannot ignore cloud feedback, as even relatively small changes in cloud properties can have significant implications for global temperature….

While we do know that clouds will likely amplify global warming, there is still a great deal of uncertainty about how strong this effect will be. Here climate models are of little help, as they can only simulate the bulk properties of the atmosphere over scales of tens of kilometres and several hours. Tiny cloud droplets form and evaporate in minutes. Models miss these small-scale details, but they’re needed for accurate predictions.

Do you notice that they are flipping back and forth between ‘water vapour’ (a gas) and condensed water droplets/ice droplets (clouds)?

It is not disputed that clouds have a noticeable and measurable effect on the weather/climate:
a) they cool the surface (and the air below them) by day by reflecting sunlight back up, and
b) they keep the surface (and the air below them) warmer at night up by reflecting infra red back down again.

Common sense and everyday observation tells us that overall, this is self-regulating and stable and areas with high relative humidity are cooler overall (with a smaller diurnal temperature range) than dry areas at the same latitude. Whatever warming effect water vapour has, it is completely reversed once it condenses to form clouds. (The latent heat of evaporation takes thermal energy from the surface and releases it higher up when water vapour condenses again, that cancels out.)

What this reminds us is that ‘water vapour’ (the gas) has very little effect, it is only when it condenses to form droplets/clouds that it makes a measurable difference (which averages out to nothing or an overall cooling).

The Skeptical Science article confirms that water vapour is a far stronger ‘greenhouse gas’ than CO2. There’s about ten times as much water vapour/water in the atmosphere as there is CO2, and water vapour absorbs and emits infra red at ten times as many more frequencies as CO2, so the fag packet calculation says the warming effect of water vapour is about a hundred times stronger than the warming effect of CO2 (admittedly with a huge margin of error).

But we have established that water vapour has very little warming effect compared to clouds. And the warming effect of CO2 is only about one percent of the warming effect of water vapour.

Ho hum. Another epic fail by the Alarmists, they have neatly disproved their own point.