Thursday, 5 March 2020

Who are the actual science deniers?

The 'consensus' narrative starts off with statements like this by the BBC:

Solar energy radiating back to space from the Earth's surface is absorbed by greenhouse gases and re-emitted in all directions. This heats both the lower atmosphere and the surface of the planet. Without this effect, the Earth would be about 30C colder and hostile to life.

There is - on average - fifty times as much H2O in the atmosphere, and H2O re-emits infra red at many more frequencies than CO2. Nonetheless, the consensus is that CO2 contributes about one-tenth of the total 30C 'greenhouse effect' = 3C. Therefore, most of the rest, is due to H2O = +/- 27C.

We can't magic away all the CO2 to see how much temperatures would fall, but H2O levels vary a lot. So we could take two cities at the same latitude (so they get the same amount of sun), one with high average relative humidity and one with low average relative humidity and compare average day and night time temperatures.

If the consensus narrative is correct, you would expect the humid city to be a bit warmer in the day time and a lot warmer in the night time. That's easily testable - I looked up the relevant figures for Bangkok (damp) and Khartoum (dry).

To my surprise, average day and night time temperatures are more or less the same in both.

Ho hum. So where's the evidence of the missing +/- 27C? Somebody? Anybody?
UPDATE I have found much better data on (fantastic site, it seems to have everything) for Bangkok and Khartoum.

Let's focus on the hottest month in each.

Bangkok - April,
Low 26C, avg 31C, high 35C, RH 71%.

Khartoum - May,
Low 28C, avg 35C, high 42C, RH 14%.

As we would expect, the 'range', difference between high and low is much smaller in Bangkok (less hot by day but warmer by night); and Khartoum is on average slightly warmer, despite being a lot drier (the opposite of the greenhouse theory, but we'll concede that one).

The most greenhouse effect you could possibly justify based on real life figures it to say that Bangkok's range is 5C smaller than Khartoum's and that somehow this is all down to extra 5C warmth at night (nobody disputes the 'extra warmth at night' bit; but the flip side of that is 'less warm in daytime', again, we'll gloss over that as a concession to the 'consensus').
OK. Based on average temp and RH, the calculator at
- Bangkok air holds 21g H2O/kg air
- Khartoum holds 5g/kg

That's a difference of 16g/kg.

The overall average H2O content in the atmosphere is about 15 g/kg. So maybe, just maybe, we are - on the whole - 5C warmer during the night thanks to H2O; and assuming H2O does not reduce temperature in the daytime (even though it does, yet another concession), you could argue for 2.5C of overall 'greenhouse effect'.

That's the very upper limit of the vaguely plausible, and miles off the consensus target of +/- 27C.
And the effect of CO2 is a small fraction of that 2.5C.
And the effects of CO2 are logarithmic.
And there is no positive CO2-H2O feedback, H2O is a self-regulating strong negative feedback effect (heat = water evaporates = clouds = rain = cooling), regardless of where that original heat came from.
And so on.


A K Haart said...

That's an interesting comparison. The whole climate game debunked in one blog post. Believers will have an answer though - they always do and that's another clue.

Bayard said...

I suspect the answer to this lies in the fact that the RH varies with distance from the surface and that while Khartoum and Bangkok may have wildly differing RH values at the surface, go up a few hundred metres and the RH becomes the same. That assumes there is no cloud cover in either city (or the same amount, but I doubt that clouds feature much in the weather in Khartoum).

Either that or H2O is not a greenhouse gas and the alarmists down at Scatalogical Science are right, it's all due to CO2.

Mark Wadsworth said...

AKH, thanks.

B, moisture content falls with height, but temperature also falls with height, so RH is much the same vertically. Go up high enough, it's so cold that even 0.1g water per cubic metre is 100% RH.

John, Uk said...

A reference to an interesting paper here....

John, Uk

Bayard said...

Mark I was suggesting more that the distribution of RH varied with height, so that whereas on the surface it could be 72% in Bangkok and 29% in Khartoum, further up, with more large scale air movement, it is possible that the RH is the same everywhere.

Physiocrat said...

From experience, we know that it is warmer at night if it is cloudy. So the cloud cover seems to have some sort of blanket effect. My guess it is reflection due to water droplets. Any thoughts on this, anyone?

Mark Wadsworth said...

J, thanks, I'll have a look

B, don't confuse units.

Ph, for sure, high RH reduces the day-night temperature range. It's cooler by day and warmer by night. But overall, RH has no effect. The alarmists say that overall, RH pushes up average by 27C. Day and night.

Bayard said...

Phys, yes, I think so too, but clouds, which are water droplets in the air and RH, which is water molecules in the air, are two separate things. A question occurs to me which is how much of the H2O in the atmosphere is in the form of water vapour (molecules) and how much is in the form of clouds (droplets)?

Mark Wadsworth said...

B, that's the problem. The definitions and the dividing line.

Droplets of water (clouds), have a blanket effect. But true water vapour also had a blanket effect, aka "muggy".

Bayard said...

Mark, I think we can agree on one thing, which is that the the Alarmists' model is at best over-simplified and at worst plain wrong. However, I have no doubt that,like most things in nature, the truth is fiendishly complicated, and fiendishly complicated doesn't sell well to the masses, unlike sweet little girls good at making speeches written by others.

Mark Wadsworth said...

B how DNA works is fiendishly complicated, as it nuclear physics or even gravity, and I don't claim to 'understand' any of these things.

But they do have very plausible explanations and fit in with what we actually observe. You or I can 'explain' evolution, nuclear physics or planets going round the sun in a few short sentences to our own and most other people's reasonable satisfaction.

Take lead in petrol - how many people know and understand what impact it has on the human brain on a molecular level? Not many, but we observe it is very damaging and it's a good job they phased it out.

So why make up implausible stuff like MMGW?

Bayard said...

Because our brains are hard-wired to believe in stuff like religion and, as GK Chesterton said "When men stop believing in God, they don't believe in nothing, they believe in anything." Also, while you are worrying about Global Warming, you are less likely to be worrying about how you're being screwed by the Elite.

Mark Wadsworth said...

B, yes, there is an element of that.