Did I Just Come Across The 'Chemtrail' Smoking Gun?

Part 3

I’m now going to look at the second citation by ARIA concerning Cirrus Cloud Seeding. Published in 2023, it is a real eye opener and quite extraordinary in my opinion, updating the ‘results’ of the 2009 ‘thought experiment’ which I looked at in Part 2, which was also cited by ARIA in defence of their ‘small scale’ geoengineering experiments. Here is what the abstract says (my highlights):

To date the climate intervention (CI) proposal of cirrus cloud thinning (CCT) was only assessed in general circulation models (GCMs) using a globally uniform distribution of artificial ice nucleating particles (INPs). In this study, we made the first attempt using the ECHAM–HAM (Hamburg Aerosol Module) GCM to simulate CCT using a fully prognostic cirrus seeding aerosol species. Seeding particles were assumed to be made of bismuth triiodide and were emitted into the atmosphere following aircraft emissions of black carbon (soot). This new approach drastically reduced the number concentration of seeding particles available as INPs in our cirrus ice nucleation sub-model compared to the globally uniform approach. As a result, we found that in order to achieve a significant signal we needed to reduce the assumed radius of emitted seeding particles by an order of magnitude to 0.01 µm and scale the mass emissions of seeding particles by at least a factor of 100 or 1000. This latter scaling factor led to a large net top-of-atmosphere (TOA) warming effect of 5.9 W m⁻². This warming effect was a clear response to overseeding with a large concentration of seeding particles (>10⁵ L⁻¹ in the Northern Hemisphere) that was most evident in the tropics. Due to this undesired effect, in a second series of simulations we avoided seeding the tropics by restricting emissions to only the Northern Hemisphere (NH) during winter. We also found a small and insignificant effect, or overseeding, which for the extreme case was reduced compared to the global aircraft emission scenario (2.2 W m⁻²). Ice crystal radius anomalies were not what we expected, with the largest reduction in size found for the case with a mass scaling factor of 10 instead of the extreme, ×1000, scenario. We attributed this peculiar behavior to the differences in the competition between different seeding particle concentrations and background particles. Finally, we also found that seeding with such large concentrations increased the albedo effect of mixed-phase clouds in the NH due to less efficient cloud droplet consumption, consistent with previous findings from our model. Overall, however, based on this study it is recommended to pause further modeling efforts of CCT unless more observational-based evidence of aerosol–ice-cloud interactions indicates favorable conditions for producing the desired outcome of this CI proposal.

Summary: the climate model ‘thought experiment’ didn’t work! So they increased the amount of cloud seeding particles emitted from jet engine exhausts by up to 1000x and it still didn’t work! In fact, it caused a net TOA warming and increased the albedo effect of mixed phase clouds:

Mixed-phase clouds represent a three-phase colloidal system consisting of water vapor, ice particles, and coexisting supercooled liquid droplets. Mixed-phase clouds are ubiquitous in the troposphere, occurring at all latitudes from the polar regions to the tropics.

The idea was to thin high level cirrus clouds composed only of ice crystals, not to enhance the albedo effect of lower level mixed phase clouds. So the ‘thought experiment’ was a failure, hence the authors’ recommendation to pause further ‘modelling’ work. Why? It does no harm, keeps academic types in generous paid employment, often at taxpayers’ expense, and who knows, by tweaking the models, they might get the right result eventually. Or was the ‘pause’ recommended for actual, ongoing field trials? Makes you wonder. There’s more:

Cirrus cloud thinning (CCT) is a climate intervention (CI) proposal with the specific aim to enhance the outgoing flux of terrestrial, longwave (LW) radiation by counteracting the net warming effect of naturally occurring cirrus clouds (Mitchell and Finnegan, 2009; Muri et al., 2014).

So 14 years later, the authors refer back to the seminal study on CCT which I looked at in Part 2. But they’ve found that the brilliant idea doesn’t work (using more climate models of course). So why are ARIA still plugging it? They refer once again to Mitchell and Finnegan (2009) and in fact they base their study on the Mitchell and Finnegan seeding protocol - namely, distribution by commercial aircraft:

Mitchell and Finnegan (2009) proposed that if CCT were implemented in the real world, a potential delivery mechanism could be to use commercial aircraft, which would have a much less homogeneous spatial extent.

Seeding particles made of bismuth triiodide (BiI₃) with a density of 5778 kg m⁻³, following Mitchell and Finnegan (2009), are included as an additional heterogeneous nucleation mode in our cirrus sub-model. The number of seeding particles available for ice nucleation in the cirrus scheme no longer follows a globally uniform approach and instead follows aircraft emissions to emulate a more realistic CI scenario.

We assume that SPs originate solely from aviation sources to emulate the proposed delivery mechanism over wide areas (Mitchell and Finnegan, 2009). Their emissions follow the same spatial and temporal distribution as BC CEDS aircraft emissions.

They even provide a nice graphic to show how the seed particles (SP) would be distributed in such a ‘hypothetical’ scenario:

Note how the US, UK and northern Europe get the motherlode of seed particles. The north Atlantic also gets heavily ‘sprayed’ whereas the vast southern oceans come off relatively unscathed.

As suggested by Mitchell and Finnegan, heterogeneous ice nucleation does indeed dominate and replace homogeneous ice nucleation:

A majority of ice in cirrus in our model originates from homogeneous nucleation (ICNC HOM) in the unseeded reference case (Fig. 4c). By adding a large concentration of seeding particles, homogeneous nucleation is almost entirely shut off in most regions and is replaced by a larger number of ice crystals that originate from heterogeneous nucleation in the mid-troposphere and the UTLS (> 1000 L⁻¹ towards the NH high latitudes, Fig. 4d).

But it doesn’t have the expected desired effect:

The large shift to heterogeneous nucleation in cirrus reduces RH values by nearly 10 % (not shown) in the same areas where we find negative cloud fraction anomalies, thus preventing the sufficiently high RH values needed for homogeneous nucleation and for full grid box coverage of cirrus. This response is in line with the intention of CCT, but the positive cloud fraction anomalies in the UTLS [upper troposphere and lower stratosphere] counteract this intended cirrus thinning (discussed below).

Oops. What they’re saying here is that seeding increased high altitude cirrus, the exact opposite of what was intended. Hmmm.

The authors summarize their findings thus:

It is clear that injecting a large number of seeding particles leads to undesirable effects in our model, with fewer but optically thicker clouds in the mid-troposphere and new cloud formation in the UTLS. The former effect is an artifact of our cloud fraction parameterization and could be addressed by using an updated method that accounts for the distinction between in-cloud and cloud-free water vapor (Muench and Lohmann, 2020). What remains uncertain is why we find larger reductions in average ice crystal size when seeding with lower concentrations, which will be examined in more detail in the next section. The main outcome of global aircraft seeding is the large impact on the tropics. Heterogeneous nucleation onto numerous seeding particles in our r0.01 high-seeding case replaces ICNC HOM and leads to tropospheric stabilization, thus reducing convective precipitation. Overall, these effects strengthen the case that cirrus seeding efforts should not target tropical regions (Storelvmo and Herger, 2014; Gasparini et al., 2017).

So not only does the process create more clouds in the upper troposphere and lower stratosphere, it leads to reduced rainfall in the tropics.

This is why buggering around with the atmosphere when you haven’t got a clue what you’re doing is not a good idea. ARIA’s own references prove it. To drive home the point, some final words from the authors of the 2023 study:

Finally, our results also call into question the reliability of CCT to act as a CI strategy. Specifically, the proposed delivery method of seeding material via commercial aircraft is uncertain as based on our results this introduces a particle size bias in order to achieve a significant signal.

Seeding particle emissions were assumed to follow aircraft emissions of black carbon (soot) particles, following the proposed real-world delivery mechanism (Mitchell and Finnegan, 2009). We found that compared to assuming a globally uniform seeding particle distribution, using aircraft emissions drastically reduces the number concentration of seeding particles available as INPs in our cirrus sub-model. However, this requires using much smaller seeding particles with high mass emission scaling in order to achieve a significant signal, which we found always led to overseeding and associated warming.

But that hasn’t stopped ARIA advocating setting up ‘small scale’ geoengineering experiments and ‘collaborating with other governments’ to do the same! Have they at least learned their lesson that pumping artificial ice nucleation particles into the upper atmosphere globally via commercial aircraft exhaust emissions is definitely not a good idea? The ‘model experiments’ prove it. Apparently not. So what are they going to try next?