The core premise of the AGW hypothesis is higher CO2 levels --> to higher global temperatures.
Yet this is *completely unsupported* by any experimental evidence!
Worse, it is ultimately only validated *by circularly assuming* the premise is true!
A thread... 👇🧵
We start with the latest publication at time of writing, the IPCC AR6.
In Chapter 7 (…) they summarize how higher CO2 levels lead to higher equilibrium temperatures.
Climate is affected by perturbations to the 'energy budget', quantified by ERFs.
1/ ipcc.ch/report/ar6/wg1…
The climate system's response to these ERFs is assessed as the Equilibrium Climate Sensitivity.
The equation is given below, relating the ERF from a doubling of CO2 concentration, to the ECS:
ECS = –ΔF2xCO2/α
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So the concentration of CO2 directly translates into an ERF, which is then used in a further equation to determine how much this will affect global equilibrium temperature.
ECS is fixed for a given ERF (doubling of CO2) but derives from Equation 7.1 with ΔN = 0
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The total anthropogenic ERF is given as 2.72 W/m^2.
The question is: *how is this model validated* such that we know it corresponds to reality?
Before answering, one must understand what an experiment is -- for detail, see the quoted thread.
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The key is to keep in mind that we are looking for experimental evidence -- no amount of calculations, modelling, or observations can substitute for a controlled experiment demonstrating CO2 causing a surface to heat up.
With that in mind, let's see how the ERFs fare...
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In 7.3 ERFs are defined.
7.3.1 indicates ERFs replaced the SARFs (stratospheric-temperature-adjusted radiative forcing) of earlier assessments.
7.3.2 indicates ERFs are estimated using SARFs plus ESMs (Earth System Models)
Let's focus just on the SARFs...
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7.3.2.1 describes that the SARF for CO2 in this AR6 assessment is based on a paper Etminan et al., 2016.
Now follows a long trail of citations. Keep in mind that at each step we are looking for the experimental verification of all this (see quoted post)
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Etminan et al. 2016 () provides "New calculations".
They update the expressions from earlier work (Myhre et al. 1998) in "a number of important ways".
The methods section describes only calculations and simulations, not experiments...
8/agupubs.onlinelibrary.wiley.com/doi/epdf/10.10…
We follow the citation to see how the earlier work was validated.
Myhre et al. 1998 () is... also "new calculations", using three "radiative transfer models".
They give no experimental validation of their new calculations...
9/agupubs.onlinelibrary.wiley.com/doi/epdf/10.10…
They appear merely to refer again to earlier work, not providing any factual experimental evidence of why their models are valid.
Looking from AR4 (2007) through AR2 (1994) only yield references to AR1 (1990) (sub-thread: ).
So we go to AR1...
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IPCC AR1 Chapter 2 (), 2.2.4 describes the approach, expressing the forcing of each gas as a function of its concentration change.
This is calculated using "radiative transfer *models*".
No experimental validation of the models is provided.
11/ipcc.ch/site/assets/up…
They refer to Hansen 1998 () for the coefficients, so we look there.
They do describe "experiments"... but, stunningly, they refer to running *model* simulations, not actual real-life experiments!
They describe model outputs and provide formulas...
12/pubs.giss.nasa.gov/docs/1988/1988…
... but no experimental evidence.
They refer to a "paper 2" to corroborate the calculations, which is Hansen et al. 1984, so, we go even further back...
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Hansen 1984 () is the first paper in this multi-decadal citation chain so far that offers something empirical to look at besides models.
The abstract says they "deduce an empirical climate sensitivity" to corroborate their 3-D global climate models.
14/pubs.giss.nasa.gov/docs/1984/1984…
How do they validate their models empirically?
Their empirical estimations imply a sensitivity of 2.5-5°C for 2x CO2 if... ...
if ... ... if "the temperature increase is due to the added greenhouse gases".
... I will let that sink in for a moment.
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...
...
...
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For the starkest possible contrast, compare again this 1984 empirical validation () with the latest AR6 2021 report (), side by side...
17/ pubs.giss.nasa.gov/docs/1984/1984…
ipcc.ch/report/ar6/wg1…
We followed every citation. We looked at all cited evidence. We did not skip any steps.
In 30+ years of research, the only corroboration provided for this concept of RF, besides more models, is an assumption of that which is to be proven, i.e. that CO2 caused rise in temps.
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If the IPCC itself does not provide citations for experimental evidence... you can be darn sure it's because they don't have any.
That's it, folks. That is the entirety of what the AGW is based on. Calculations based on an initial 1984 assumption.
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And throughout the years, simply more observations, models, and calculations, all continuing with the (unproven) *assumption* that CO2 causes higher temperatures.
It is literally nothing but an assumed premise. A big hullabaloo. Much ado about nothing.
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This is why if you ask for experimental evidence for the AGW, you will either be derided, mocked, hit with "it's the consensus", or provided links that aren't actually experiments () or don't actually show the GHE ().
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pubs.acs.org/doi/10.1021/ac…
There is nothing underlying this theory, it all rests upon nothing.
As to why it is happening, why so many believe, why this wreaks so much havoc in the world... that is a topic for another day.
fin/
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