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?
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UPDATE I have found much better data on timeanddate.com (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 Lenntech.com:
- 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.