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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Notes on stratospheric aerosol injection</title>
<link rel="stylesheet" href="https://esm.sh/jsr/@celine/[email protected]/cell.css" />
<link rel="stylesheet" href="https://esm.sh/jsr/@celine/[email protected]/libertine.css" />
<script type="module" src="https://esm.sh/jsr/@celine/[email protected]"></script>
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<main>
<h1>Notes on stratospheric aerosol injection</h1>
<p>
Stratospheric aerosol injection (SAI) is a type of climate engineering that involves injecting reflective
particles into the stratosphere to reflect sunlight and cool the Earth. SAI is a form of solar geoengineering that
could help offset some of the warming caused by greenhouse gas emissions.
</p>
<!-- <h2>Proposal</h2>
<p>Maybe there should be a <a href="https://en.wikipedia.org/wiki/Stratospheric_aerosol_injection">Stratospheric aerosol injection</a> (SAI), venture backed, for-profit startup on Australian soil.</p> -->
<h2>Legality</h2>
<p>
SAI is legal in the United States under the
<a
href="https://library.noaa.gov/weather-climate/weather-modification-project-reports#:~:text=Weather%20modification%20activities%20are,management%20activities%20and%20experiments">
Weather Modification Act of 1976
</a><sup><bh-cite>makesunsets2024faq</bh-cite></sup>.
</p>
<p>
Unlike the United States, <q>Australia is a party to the <a
href="https://en.wikipedia.org/wiki/Convention_on_Biological_Diversity">United Nations Convention on
Biological Diversity</a>, which includes an agreement to restrict climate geoengineering unless it is for
small-scale scientific research, or unless the risks and scientific basis are appropriately considered <a
href="https://cdrlaw.org/wp-content/uploads/2021/10/CBD-COP-10-Decision-X33.pdf">(Decision X/33,
2010)</a>.</q><sup><bh-cite>bowen2024hansard</bh-cite></sup>.
In fact, <q>all UN member states with the exception of the United States - have ratified the
treaty</q><sup><bh-cite>enwiki:1257418714</bh-cite></sup>.
</p>
<figure>
<img
src="https://upload.wikimedia.org/wikipedia/commons/thumb/5/5a/Convention_on_Biological_Diversity2.svg/2880px-Convention_on_Biological_Diversity2.svg.png"></img>
<figcaption>
<span style="background-color:#00aa00;"> </span> Parties to the convention</div>
<span style="background-color:#926ec6;"> </span> Signed, but not ratified</div>
<span style="background-color:#ff9911;"> </span> Non-signatory</div>
</figure>
<h2>Theory</h2>
Stratospheric solar geoengineering without ozone loss.<sup><bh-cite>keith2016</bh-cite></sup>
<br />
Cost analysis of stratospheric albedo modification delivery systems.<sup><bh-cite>mcclellan2012</bh-cite></sup>
<br />
Abrupt reduction in shipping emission as an inadvertent geoengineering termination shock produces substantial
radiative warming.<sup><bh-cite>yuan2014</bh-cite></sup>
https://salatainstitute.harvard.edu/an-update-on-scopex/
https://geoengineering.environment.harvard.edu/frank-keutsch-stratospheric-controlled-perturbation-experiment
https://www.technologyreview.com/2024/04/04/1090626/the-hard-lessons-of-harvards-failed-geoengineering-experiment/
https://scopexac.com/finalreport/
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024GL109077
https://gmd.copernicus.org/articles/17/7767/2024
<h2>References</h2>
<bh-reference id="makesunsets2024faq">
@misc{makesunsets2024faq,
title = {FAQ -- Make Sunsets},
author = {{Make Sunsets}},
year = {2024},
url = {https://makesunsets.com/pages/faq},
note = {Accessed: 2024-12-05},
organization = {Make Sunsets},
keywords = {stratospheric aerosol injection, climate engineering, solar geoengineering},
abstract = {Frequently asked questions about Make Sunsets' stratospheric aerosol injection program using balloons
to launch reflective clouds into the stratosphere for solar radiation management and climate cooling.}
}
</bh-reference>
<bh-reference id="bowen2024hansard">
@misc{bowen2024hansard,
title = {Petitions - Geoengineering: Ministerial Response},
author = {Bowen, Chris},
year = {2024},
month = {2},
day = {12},
institution = {Parliament of Australia},
type = {Parliamentary Speech},
note = {House of Representatives Hansard},
url =
{https://www.aph.gov.au/Parliamentary_Business/Hansard/Hansard_Display?bid=chamber/hansardr/27600/&sid=0198},
abstract = {Ministerial response to petition EN5472 regarding inquiry into geoengineering, outlining the
Australian Government's position on climate change science and geoengineering technologies.}
}
</bh-reference>
<bh-reference id="keith2016">
@article{doi:10.1073/pnas.1615572113,
author = {David W. Keith and Debra K. Weisenstein and John A. Dykema and Frank N. Keutsch },
title = {Stratospheric solar geoengineering without ozone loss},
journal = {Proceedings of the National Academy of Sciences},
volume = {113},
number = {52},
pages = {14910-14914},
year = {2016},
doi = {10.1073/pnas.1615572113},
URL = {https://www.pnas.org/doi/abs/10.1073/pnas.1615572113},
eprint = {https://www.pnas.org/doi/pdf/10.1073/pnas.1615572113},
abstract = {The combination of emissions cuts and solar geoengineering could reduce climate risks in ways that
cannot be achieved by emissions cuts alone: It could keep Earth under the 1.5-degree mark agreed at Paris, and it
might stop sea level rise this century. However, this promise comes with many risks. Injection of sulfuric acid
into the stratosphere, for example, would damage the ozone layer. Injection of calcite (or limestone) particles
rather than sulfuric acid could counter ozone loss by neutralizing acids resulting from anthropogenic emissions,
acids that contribute to the chemical cycles that destroy stratospheric ozone. Calcite aerosol geoengineering may
cool the planet while simultaneously repairing the ozone layer. Injecting sulfate aerosol into the stratosphere,
the most frequently analyzed proposal for solar geoengineering, may reduce some climate risks, but it would also
entail new risks, including ozone loss and heating of the lower tropical stratosphere, which, in turn, would
increase water vapor concentration causing additional ozone loss and surface warming. We propose a method for
stratospheric aerosol climate modification that uses a solid aerosol composed of alkaline metal salts that will
convert hydrogen halides and nitric and sulfuric acids into stable salts to enable stratospheric geoengineering
while reducing or reversing ozone depletion. Rather than minimizing reactive effects by reducing surface area
using high refractive index materials, this method tailors the chemical reactivity. Specifically, we calculate
that injection of calcite (CaCO3) aerosol particles might reduce net radiative forcing while simultaneously
increasing column ozone toward its preanthropogenic baseline. A radiative forcing of −1 W⋅m−2, for example, might
be achieved with a simultaneous 3.8\% increase in column ozone using 2.1 Tg⋅y−1 of 275-nm radius calcite aerosol.
Moreover, the radiative heating of the lower stratosphere would be roughly 10-fold less than if that same
radiative forcing had been produced using sulfate aerosol. Although solar geoengineering cannot substitute for
emissions cuts, it may supplement them by reducing some of the risks of climate change. Further research on this
and similar methods could lead to reductions in risks and improved efficacy of solar geoengineering methods.}
}
</bh-reference>
<bh-reference id="yuan2014">
10.1038/s43247-024-01442-3
</bh-reference>
<bh-reference id="mcclellan2012">
@article{mcclellan2012,
doi = {10.1088/1748-9326/7/3/034019},
url = {https://dx.doi.org/10.1088/1748-9326/7/3/034019},
year = {2012},
month = {aug},
publisher = {IOP Publishing},
volume = {7},
number = {3},
pages = {034019},
author = {Justin McClellan and David W Keith and Jay Apt},
title = {Cost analysis of stratospheric albedo modification delivery systems},
journal = {Environmental Research Letters}}
<!-- abstract = {We perform engineering cost analyses of systems capable of delivering 1–5 million metric tonnes (Mt) of albedo modification material to altitudes of 18–30 km. The goal is to compare a range of delivery systems evaluated on a consistent cost basis. Cost estimates are developed with statistical cost estimating relationships based on historical costs of aerospace development programs and operations concepts using labor rates appropriate to the operations. We evaluate existing aircraft cost of acquisition and operations, perform in-depth new aircraft and airship design studies and cost analyses, and survey rockets, guns, and suspended gas and slurry pipes, comparing their costs to those of aircraft and airships. Annual costs for delivery systems based on new aircraft designs are estimated to be $1-3B to deliver 1 Mt to 20 30 km or $2-8B to deliver 5 Mt to the same altitude range. Costs for hybrid airships may be competitive, but their large surface area complicates operations in high altitude wind shear, and development costs are more uncertain than those for airplanes. Pipes suspended by floating platforms provide low recurring costs to pump a liquid or gas to altitudes as high as 20km, but the research, development, testing and evaluation costs of these systems are high and carry a large uncertainty; the pipe system’s high operating pressures and tensile strength requirements bring the feasibility of this system into question. The costs for rockets and guns are significantly higher than those for other systems. We conclude that (a) the basic technological capability to deliver material to the stratosphere at million tonne per year rates exists today, (b) based on prior literature, a few million tonnes per year would be sufficient to alter radiative forcing by an amount roughly equivalent to the growth of anticipated greenhouse gas forcing over the next half century, and that (c) several different methods could possibly deliver this quantity for less than $8B per year. We do not address here the science of aerosols in the stratosphere, nor issues of risk, effectiveness or governance that will add to the costs of solar geoengineering.}} -->
</bh-reference>
<bh-reference id="enwiki:1257418714">
@misc{ enwiki:1257418714,
author = "{Wikipedia contributors}",
title = "Convention on Biological Diversity --- {Wikipedia}{,} The Free Encyclopedia",
year = "2024",
howpublished =
"\url{https://en.wikipedia.org/w/index.php?title=Convention_on_Biological_Diversity&oldid=1257418714}",
note = "[Online; accessed 5-December-2024]"
}
</bh-reference>
<bh-bibliography>
</bh-bibliography>
</main>
</body>
</html>