<p>My question was naïve to the weather dynamics —so the answer is <em>technical</em>: the heat is on the ground, not in the stratosphere.</p>
<p>So there are two things, infrared deflection into space and radiative cooling, wherein heat gets emitted as infrared radiation into space —the two blend into each other, but stratospheric clouds primarily do the former.
Given that the hot weather system originated from the south (Sahara) it would be mostly pointless deflecting incoming IR rays, which are not causing the heat in that precise spot. The heat was also on the ground not in the atmosphere, so irradiative cooling up high would be ineffective. After all, on cloudy days during the heatwaves, the temperatures were still well above average during both the daytime and <em>nightime</em>. The nightime detail is because the heat irradiated by the ground via irradiative cooling was being deflected back by the (tropospheric) cloud cover, so in effect an IR mirror is a bad thing as the heat was from the sub but not from there.
Similarly, it has recently been proposed that the norther polar vortex (a continuous cyclone that traps the cold in the artic) could be stabilised via stratospheric aerosol injection. Controversies apart, the aim would be to deflect incoming rays, not irradiate stratospheric heat.</p>
<p>There are ground-based technologies that employ radiative cooling (ranging from TiO2 white paint to theoretical nanoengineered panels from IEEE papers). Being more targetted they can be used to tackle the &quot;urban heat island effect&quot; wherein parts of a developed areas can be several degrees higher. So these would be a better safeguard against extreme heatwaves assuming we are unable to rapidly remove 950 gigatons of carbon dioxide by growing new biomass or sequestering it underground.</p>

CC BY-SA 4.0
2023-02-19T10:32:31.817Z
Yes, the lightening of surface properties is one meagre solution. If the above air is saturated with greenhouse gases, the reflected rays are scattered back to Earth warming the surface lightly if not more. The best solutions are planting more trees, protecting wetlands and reducing carbon emissions. That is focusing on more natural rehabilitation programs and less in artificial Engineering of the land surfaces.
Gemechu Fanta Garuma
CC BY-SA 4.0
2022-09-16T11:20:43.377Z
2022-09-16T11:20:43.377Z
Matteo Ferla
<p>The heatwave that hit Europe in July was not only highly unpleasant (40°C), but has been predicted to be an exceptionally onerous medical, agricultural and economic burden. As someone outside of the field, I was wondering why attempts involving stratospheric aerosol releases to combat heatwaves in southern Europe are not discussed. The Wikipedia article on <a href="https://en.wikipedia.org/wiki/Stratospheric_aerosol_injection" rel="nofollow noreferrer">stratospheric aerosol injection</a> lists several real, possible and perceived drawbacks, but focuses on it as an impractically expensive global solution as opposed to being used temporarily to reduce heatwaves.  Despite extrapolations from a 2006 Californian heatwave test of a reduction of 7°C <a href="https://acp.copernicus.org/articles/13/6373/2013/" rel="nofollow noreferrer">[ref]</a>.</p>
<p>Is the <em>lack of discussion on temporary regional usage of aerosol injection for heatwaves</em> simply caused by non-technical factors like:</p>
<ul>
<li>a lack of political willpower (as the Extinction Rebellion protests in the UK and petitions such as <a href="https://www.change.org/p/un-voto-per-il-clima" rel="nofollow noreferrer">this one</a> suggest)</li>
<li>ethical objections (e.g. we should save wildlife and cut pollution
rather than engineer the climate)</li>
<li>its cost and lack of awareness outside of scientific circles (the aforementioned Wikipedia page is <a href="https://pageviews.wmcloud.org/?project=en.wikipedia.org&amp;platform=all-access&amp;agent=user&amp;redirects=0&amp;start=2021-08-01&amp;end=2022-07-31&amp;pages=Stratospheric_aerosol_injection%7CSnowpiercer_(TV_series)" rel="nofollow noreferrer">visited only 200 times a day, ten fold less than Snowpiercer</a>, a post-apocalyptic Netflix show with it as a wild premise)</li>
<li>its experimental state (even if it was tested 16 years ago with some success —as far as I can tell)</li>
</ul>
<p>Or is the reason technical: from what I understand European heatwaves are caused by anticyclones from Africa (or at least the meteorological offices give these media friendly names like Charon, Scipio or Hannibal) so the solar irradiation was not originally collected in the affected areas (but in the Sahara) so aerosol injections would not work (or worse would trap the heat at night or exacerbate the anti-cyclone)?</p>
<p>What is holding back this option?</p>
<hr>
<p><em>Footnote.</em> there's a related <a href="https://earthscience.stackexchange.com/questions/24054/could-stratospheric-aerosol-injection-be-used-to-fine-tune-climate-locally">Q here</a>, but it's both unanswered and broad. I am more interested in Europe and heatwaves, hence my opening a new Q.</p>

CC BY-SA 4.0
2022-08-08T07:29:00.763Z
Sure, let's tamper with the atmosphere some more. What could go wrong? *hint: A lot. Also, short term mitigations of long term problems don't solve these. There's a reason why any scheme to becoming more sustainable starts with "reduce" and not "re-engineer".
Erik
CC BY-SA 4.0
2022-08-28T08:37:33.263Z
Do you want to experiment with the only planet known to have life sustaining environments? I don't think so, especially when the science of aerosol radiative forcing is not clear. The experiment has to be first performed in labs and computations. The results have to be verified by experts in the field. These hasn't been done yet and nobody knows the consequences of these interventions.
Gemechu Fanta Garuma
CC BY-SA 4.0
2022-09-16T13:36:31.347Z
@GemechuFantaGaruma it could of course be argued that the only life sustaining planet is already being tampered with, both unintentionally (on the same scale) and intentionally (at smaller scales).  I do agree wholly that attempts at massive planetary engineering are extremely dicey prospects, and don't make me comfortable... but discussion/questioning/pondering are the beginning of any eventual science... hopefully we're careful that anything ever done is done with the utmost of caution and extreme scientific rigor.
JeopardyTempest
CC BY-SA 4.0
2022-09-16T13:59:21.690Z
Yes, I would say that the lack of discussion makes questionable applications more likely as has happened in medicine. In geoengineering as far as I understand (not my field) one _could_ argue it is happening in the [UAE](https://en.wikipedia.org/wiki/Cloud_seeding_in_the_United_Arab_Emirates) where cloud seeding is basically being used to terraform what were deserts.
Matteo Ferla
<climate-change><geoengineering><cyclone><aerosol>
Aerosol injections to manage European heatwaves?
Matteo Ferla
# Aerosol injections to manage European heatwaves?

(Asked by: username_0 on 2022-08-07)

The heatwave that hit Europe in July was not only highly unpleasant (40°C), but has been predicted to be an exceptionally onerous medical, agricultural and economic burden. As someone outside of the field, I was wondering why attempts involving stratospheric aerosol releases to combat heatwaves in southern Europe are not discussed. The Wikipedia article on [stratospheric aerosol injection](https://en.wikipedia.org/wiki/Stratospheric_aerosol_injection) lists several real, possible and perceived drawbacks, but focuses on it as an impractically expensive global solution as opposed to being used temporarily to reduce heatwaves. Despite extrapolations from a 2006 Californian heatwave test of a reduction of 7°C [[ref]](https://acp.copernicus.org/articles/13/6373/2013/).

Is the *lack of discussion on temporary regional usage of aerosol injection for heatwaves* simply caused by non-technical factors like:

* a lack of political willpower (as the Extinction Rebellion protests in the UK and petitions such as [this one](https://www.change.org/p/un-voto-per-il-clima) suggest)
* ethical objections (e.g. we should save wildlife and cut pollution
  rather than engineer the climate)
* its cost and lack of awareness outside of scientific circles (the aforementioned Wikipedia page is [visited only 200 times a day, ten fold less than Snowpiercer](https://pageviews.wmcloud.org/?project=en.wikipedia.org&platform=all-access&agent=user&redirects=0&start=2021-08-01&end=2022-07-31&pages=Stratospheric_aerosol_injection%7CSnowpiercer_(TV_series)), a post-apocalyptic Netflix show with it as a wild premise)
* its experimental state (even if it was tested 16 years ago with some success —as far as I can tell)

Or is the reason technical: from what I understand European heatwaves are caused by anticyclones from Africa (or at least the meteorological offices give these media friendly names like Charon, Scipio or Hannibal) so the solar irradiation was not originally collected in the affected areas (but in the Sahara) so aerosol injections would not work (or worse would trap the heat at night or exacerbate the anti-cyclone)?

What is holding back this option?

---

*Footnote.* there's a related [Q here](https://earthscience.stackexchange.com/questions/24054/could-stratospheric-aerosol-injection-be-used-to-fine-tune-climate-locally), but it's both unanswered and broad. I am more interested in Europe and heatwaves, hence my opening a new Q.

**Tags:** climate-change, geoengineering, cyclone, aerosol

> **Comments:**
> **username_1**: Sure, let's tamper with the atmosphere some more. What could go wrong? *hint: A lot. Also, short term mitigations of long term problems don't solve these. There's a reason why any scheme to becoming more sustainable starts with "reduce" and not "re-engineer".  
> **username_2**: Do you want to experiment with the only planet known to have life sustaining environments? I don't think so, especially when the science of aerosol radiative forcing is not clear. The experiment has to be first performed in labs and computations. The results have to be verified by experts in the field. These hasn't been done yet and nobody knows the consequences of these interventions.  
> **username_3**: @username_2 it could of course be argued that the only life sustaining planet is already being tampered with, both unintentionally (on the same scale) and intentionally (at smaller scales).  I do agree wholly that attempts at massive planetary engineering are extremely dicey prospects, and don't make me comfortable... but discussion/questioning/pondering are the beginning of any eventual science... hopefully we're careful that anything ever done is done with the utmost of caution and extreme scientific rigor.  
> **username_0**: Yes, I would say that the lack of discussion makes questionable applications more likely as has happened in medicine. In geoengineering as far as I understand (not my field) one _could_ argue it is happening in the [UAE](https://en.wikipedia.org/wiki/Cloud_seeding_in_the_United_Arab_Emirates) where cloud seeding is basically being used to terraform what were deserts.  

---

## 1 answers

### Answer by username_0 on 2022-09-16. Score: 1 | Accepted answer

My question was naïve to the weather dynamics —so the answer is *technical*: the heat is on the ground, not in the stratosphere.

So there are two things, infrared deflection into space and radiative cooling, wherein heat gets emitted as infrared radiation into space —the two blend into each other, but stratospheric clouds primarily do the former.
Given that the hot weather system originated from the south (Sahara) it would be mostly pointless deflecting incoming IR rays, which are not causing the heat in that precise spot. The heat was also on the ground not in the atmosphere, so irradiative cooling up high would be ineffective. After all, on cloudy days during the heatwaves, the temperatures were still well above average during both the daytime and *nightime*. The nightime detail is because the heat irradiated by the ground via irradiative cooling was being deflected back by the (tropospheric) cloud cover, so in effect an IR mirror is a bad thing as the heat was from the sub but not from there.
Similarly, it has recently been proposed that the norther polar vortex (a continuous cyclone that traps the cold in the artic) could be stabilised via stratospheric aerosol injection. Controversies apart, the aim would be to deflect incoming rays, not irradiate stratospheric heat.

There are ground-based technologies that employ radiative cooling (ranging from TiO2 white paint to theoretical nanoengineered panels from IEEE papers). Being more targetted they can be used to tackle the "urban heat island effect" wherein parts of a developed areas can be several degrees higher. So these would be a better safeguard against extreme heatwaves assuming we are unable to rapidly remove 950 gigatons of carbon dioxide by growing new biomass or sequestering it underground.

> **Comments:**
> **username_2**: Yes, the lightening of surface properties is one meagre solution. If the above air is saturated with greenhouse gases, the reflected rays are scattered back to Earth warming the surface lightly if not more. The best solutions are planting more trees, protecting wetlands and reducing carbon emissions. That is focusing on more natural rehabilitation programs and less in artificial Engineering of the land surfaces.  

---

