Thursday, 21 May 2020

Missing figures round - how do you make the IPCC's figures add up?

Here's our baseline energy budget, averaged over 24 hours. I have been battling with this for the past 48 hours (hence no post yesterday) and have pinned down its fatal flaw:

We see that the Earth's surface receives, on average, 493 W/m2, consisting of 161 incoming solar radiation (ignore the one-eighth that is reflected straight back) plus 333 back radiation. The average temperature of the surface is 288K. That's our starting point.

If we had no atmosphere, the Earth's surface would receive 298 W/m2 incoming solar radiation, i.e. the 341 minus the one-eighth that would be reflected straight back, and its temperature would be about 250K - 255K (opinions differ). That's another fixed point.

So as a check, to see if we are on the right track, let's see if we can what calculate Earth's average surface temperature would be without an atmosphere.

You convert W/m2 to temperature in K as follows. You need to have a starting position (493 W/m2 and 288K). If W/m2 change, then the change in temperature to the fourth power is proportional to the change in W/m2.

298/493 = 0.605
0.605 x 288K ^ 4 (6.88 billion) = 4.16 billion
4.16 billion ^ 0.25 = 254K.

Excellent! It is widely agreed that the average temperature of the Earth, if it had no atmosphere, would be around 254K, so it stacks up so far.

Now, let's do the same exercise for night-time and day-time (working backward from temperature to find W/m2).


Typical average Earth night-time temperature is (say) 7C = 280K.
280K^4/288K^4 = 0.893. 0.893 x 493 W/m2= 441 W/m2.
Therefore, Earth's surface must be receiving 441 W/m2 at night.
At night, the earth is clearly getting no incoming solar radiation.
Let's assume the back radiation is the same (333 W/m2).
That gives us a missing figure of 108 W/m2.

Does anybody know where this missing 108 W/m2 comes from?


To have an average day-time temperature of (say) 22C = 295K, total incoming radiation must be 541 W/m2 (work it out yourself).
It's seems fair to assume that during the day, the Earth's surface is getting twice the average incoming solar radiation (that is how it is calculated) = 161 x 2 = 322.
The Earth's surface must be getting at least as much back radiation by day as it does on average = 333 W/m2.
That's a total of 655 W/m2 incoming. This would give an average day-time temperature of 309K = 36C, which is clearly nonsense.
To get the 541 W/m2, the amount of back radiation must be 114 W/m2 less than the average, which is also clearly nonsense.
UPDATE - I think I have cracked it, see next post.
IMHO, the whole thing is a load of nonsense, it just crumbles under closer inspection, so using it to try and reconcile know and sensible figures is like trying to prove that the square root of the colour blue equals a banana.

The correct way to explain/reconcile Earth's average surface temperature with incoming solar radiation - which works by day or by night, with or without an atmosphere - is intuitive, relatively easy to calculate (once you know how), and completely different to their model.

So my next challenge is to re-state all their figures to reconcile W/m2 and temperature for the overall average position; the position if we had no atmosphere; night-time and day-time. I think I know what they missed, possibly deliberately (i.e. what they missed is the latent heat of evaporation/condensation and the temperature/potential energy trade offs when air rises or falls). But maybe I'm wrong :-)


Bayard said...

"so using it to try and reconcile know and sensible figures is like trying to prove that the square root of the colour blue equals a banana."

That's a complete misuse of the diagram. You're supposed to use it to show that burning fossil fuels is a Bad Thing to people who don't know the first thing about physics. It does that really quite well.

Mark Wadsworth said...

B, the over egged the pudding. I was quite happy going along with the consensus until they turned intuitive "sounds ok" type logic into a pseudo-science.

Dinero said...

The missing night time component, could that be accounted for in the heat already in the ground dissipating slowly during the night.
The day temp also contains the heat from the previous day , which is another complication, and so It could be the case that the data from that chart can not be split over day and night.

Mark Wadsworth said...

Din, ta, but it think I've found it. They messed up latent energy and potential energy.

mombers said...

Again, are you going to submit this to a journal for peer review?

Bayard said...

Mombers, but who are Mark's peers? Not scientists, 'cos he ain't a scientist and I'm not sure that the Journal of Accountancy, or whatever it's called, would be very interested.

Mark Wadsworth said...

M, these are all just glimpses, one day I will try and reconcile all the different bits - Barometric Formula, the heat/potential energy trade off and lapse rate, then I have to reconcile this one (I have done actually, just not posted yet) and even more difficult is to slot in latent heat of evaporation. Heat disappears somewhere and reappears somewhere else some time later.

I asked an actual scientist about the potential energy thingy, and he said, it seems very plausible (although not conclusive), so that was reassuring.

B, if and when I ever finish, I'll send it to some proper scientists and hopefully one of them will get it published. If I get a mention, that's a bonus but not important.

Bayard said...

Mark that's a bit like one of my favourite cartoons, which shows a lot of men in suits round a table and one woman, with one of the men saying "That's a very good point, Miss Jones, perhaps one of the men would like to make it."