Wednesday, 17 April 2019

Truncated Y-Axis Of The Week

From Watts Up With That:

The greenhouse gasses keep the Earth 30° C warmer than it would otherwise be without them in the atmosphere, so instead of the average surface temperature being -15° C, it is 15° C. Carbon dioxide contributes 10% of the effect so that is 3° C. The pre-industrial level of carbon dioxide in the atmosphere was 280 ppm. 

So roughly, if the heating effect was a linear relationship, each 100 ppm contributes 1° C. With the atmospheric concentration rising by 2 ppm annually, it would go up by 100 ppm every 50 years and we would all fry as per the IPCC predictions.

But the relationship isn’t linear, it is logarithmic. In 2006, Willis Eschenbach posted this graph on Climate Audit showing the logarithmic heating effect of carbon dioxide relative to atmospheric concentration:

As you can sees the, y-axis goes from 230 to 270, that's key to this.
We can assume that W/m2 are related to temperatures. As a guide, from Wiki: When 1361 W/m2 is arriving above the atmosphere (when the sun is at the zenith in a cloudless sky), direct sun is about 1050 W/m2, and global radiation on a horizontal surface at ground level is about 1120 W/m2.
From Skeptical Science:

After publishing my experiences talking to science 'dismissives' (or 'skeptics', or whatever you'd like to call them) and then participating in the excellent Denial101x course, I was invited to join the volunteer team at SkepticalScience last year.

Good start, a few ad hominems (refreshingly absent from the first article) to strengthen your case. Einstein famously opened his Theory of General Relativity with "Sit on this and swivel, Newton, you wig-wearing English prick!" Back to the article:

But before all that, one of the dismissives drew my attention to a climate science paradox... Scientists agree that the greenhouse effect is approximately logarithmic — which means that as we add more CO2 to the atmosphere, the effect of extra CO2 decreases.

In the last million years, CO2 levels have cycled between about 180 and 280 ppm during cycles about 100,000 years long. Because this happened in the steep part of the curve, a change of only 100 ppm (together with the Milankovich cycles) was enough to move the world in and out of the ice ages. Even though humans have increased the CO2 concentration by 130 ppm already, this extra 130 ppm has a smaller effect than the 100 ppm that was added naturally before.

But let's zoom in on the part that we actually care about: the modern era:

After zooming in, the logarithm doesn't make such a big difference: it's not far from a straight line. 560ppm will probably take us well beyond the Paris target of 1.5°C, so the 280-560 range is key; we would be unwise to let our civilization go beyond 560.
Sure, looked at close up, any part of any curve looks like a straight-ish line. But look at the y-axis, it goes from 0 to 4.5. The W/m2 increase (resulting from a CO2 increase from 280 to and 560 ppm) of just under 4 agrees to the first chart, which shows an increase from 257 to 261. But the y-axis is a tad misleading, to say the least.

They are also (deliberately?) confusing units. Fag packet* says 3.7 additional W/m2 = temperature increase (if CO2 levels doubled from pre-industrial levels) no more than 1C.

* Average earth surface temperature 288K ÷ 1,120 W/m2 (when sun directly overhead in a cloudless sky) x 3.7 W/m2 = 0.95K or 0.95C.

If we go by the first, more optimistic chart, the increase would be barely measurable, but let's give the warmenists the benefit of the doubt.


Radical Rodent said...

Then there is the possibility that there is no “greenhouse effect”, anyway;

I have yet to see anyone address this argument, scientifically; all I have ever seen is ad hominem attacks on its author.

My own hypothesis is that the atmosphere, itself, is what keeps the temperatures on Earth’s surface reasonable, more or less regardless of its components. The Sun heats the surfaces; air in contact with those surfaces is warmed, which results in it rising (hot air rises, remember?). This rising air draws in cooler air, and so the heat is distributed through the atmosphere. At night, the reverse happens, where the surface of the Earth radiates its energy to space; air moving over these cooling surfaces is then cooled; however, cool air sinks, so air movement, i.e. wind, is essential to this process. When there is little or no wind, the surface can cool such that it becomes considerably cooler than the air immediately above it – this can be seen by frosty ground, with air temperatures above it being higher (personally, I have slipped on ice on the in the Persian Gulf area, while the air above was warm enough for warm-weather clothes). It is the movement of the air that distributes the heat, rather than the presence of “greenhouse gases” that “trap” this heat.

Mark Wadsworth said...

RR, yes of course. I ask the warmenists, ok, so why is the centre of a gas giant that gets naff all sunlight 1,000s of degrees?

Surface temperature can be calculated knowing
1. Distance from sun
2. Thickness/mass of atmosphere, regardless of composition.

We used to "know' this, but it has been erased from history.

Dinero said...

What is the issue concerning logarithmic.

Mark Wadsworth said...

D, put crudely, it's like adding extra blankets. The first one or two make a big difference. More than that, you get barely warmer.

Bayard said...

"560ppm will probably take us well beyond the Paris target of 1.5°C, so the 280-560 range is key; we would be unwise to let our civilization go beyond 560."

A classic bit of Warmenist misdirection. He knows that an increase to 560ppm will only add 1 degree, so throws in a "probably" to allow him to imply that it would be beyond the Paris Accord target of 1.5 degree (which, in itself, is a completely arbitrary figure) without actually lying.

Sackerson said...

Perhaps you could open a separate page on this topic and title it "Warminster"?

Dinero said...

The first 280 increment on the x axis has 27 and the following 280 increment on the x axis has 4.5 and so it is logarithmic, the controversy on the Wattsupwiththat article is about water vapour.

Matt said...

Surely Sir David Attenborough can't be mistaken can he? The BBC say the science is settled (or to put it another way, we no platform anyone who disagrees).

James Higham said...

...Einstein famously opened his Theory of General Relativity with "Sit on this and swivel, Newton, you wig-wearing English prick!" ...

Yes, well attested, that.

Xtasorcery ( said...

Climate change is fraught with difficulties as a science. For example, we know the Earth naturally heats up and cools at variant time periods. Who's to say this recent advance isn't natural? After all, it's not THAT much at the current time.

Anyway, I'd like to invite you to come to my blog to comment, and comment frequently. Check it out at:

Love to have you there as a permanent commenter.

Graeme said...

In Finland, a "far right" party has attained parity with the usual social democrat numpties by saying that the costs of combatting climate change will hurt family pets

Mark Wadsworth said...

B, yes.

S, I'm no expert, I just apply their actual logic.

Din, sorry not clear what you mean.

M, DA is a white supremacist nutcase*, just ignore him. (* Optimum Population Trust's message seems to be "Stop the darkies having so many children." Why is that anybody else's business?)

JH, thanks.

SG, I'll have a look.

G, that's brilliant. Up to the Remainer standards of bollocks.