Hi Clive and Oswald,
The authors of the paper below state, that enhanced stratospheric
sulfate aerosol levels from volcanic eruptions or artificial
stratospheric sulfate injection would induce *significant* stratospheric
ozone depletion.
Volcanic sulfate injections are only during the volcanic maximum
eruption period active. These eruption periods last very seldom more
than a month. Stratospheric Aerosol Injection (SAI) periods are longer
than 100 years. Hence the skin cancer inducing UV-C radiation problem
induced by the stratospheric ozone depletion will also last for more
than 100 years.
Because we know some much more economic and efficient climate
restoration methods this should make no problems for climate restoration.
Franz
Am 17.10.2025 um 13:32 schrieb Geoengineering News:
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025JD043786?af=R
*Authors: *Laila V. Howar, Ross J. Salawitch, David M. Wilmouth, Eric
J. Hintsa, Jennifer S. Hare, Thomas F. Hanisco, Jason M. St. Clair,
Erin R. Delaria, Elliot L. Atlas, Sue Schauffler, Kate R. Smith,
Jessica B. Smith, Bradley D. Hall, Fred L. Moore, Jasna V. Pittman,
Bruce Daube, T. Paul Bui, Yaowei Li, Frank N. Keutsch, David S.
Sayres, Steven C. Wofsy, Jonathan Dean-Day, Stephen Donnelly, Victoria
A. Treadaway, James G. Anderson, Cameron R. Homeyer, Kenneth P. Bowman
*14 October 2025*
https://doi.org/10.1029/2025JD043786
*Abstract*
Studies have suggested that ClO could be enhanced within convectively
influenced air masses in the North American Monsoon Anticyclone due to
low temperature and elevated water mixing ratio conditions that are
conducive to chlorine activation, potentially leading to significant
loss of ozone in the midlatitude lowermost stratosphere. We analyze in
situ measurements of temperature, pressure, ClO, ClONO2, H2O, NO2,
aerosol surface area density (SAD), and organic chlorine species
obtained by instruments aboard the NASA ER-2 over the continental US
during the Dynamics and Chemistry of the Summer Stratosphere (DCOTSS)
campaign to show that chlorine activation large enough to affect loss
of ozone was not observed, for the summers of 2021 and 2022. During
both deployments, tropopause-overshooting convection with water vapor
and temperature conditions suitable for chlorine activation were
sampled. Due to their relatively young chemical age, most of these
cold and wet air masses had abundances of inorganic chlorine (Cly) too
low to support eventual enhancements of ClO that would lead to
widespread ozone depletion. Even in the few air masses with higher
levels of Cly, the abundance of nitrogen oxides was elevated and the
ratio of ClONO2 to Cly was observed to be very low, limiting the
availability of ClONO2 to react with HCl and sustain chlorine
activation. However, we show that for the average chemical and
meteorological conditions of cold, wet, overshooting air parcels
observed during DCOTSS, significant chlorine activation could occur if
stratospheric sulfate SAD were enhanced by major volcanic eruptions or
_climate intervention efforts._
*Plain Language Summary*
Stratospheric ozone shields life on Earth from the Sun's harmful
ultraviolet rays. Mixed-phase chemical reactions, which typically
occur only at very low temperatures, produce large amounts of chlorine
monoxide (ClO), a chemical that rapidly depletes stratospheric ozone.
Previous studies have hypothesized that abundances of ClO, capable of
leading to substantial ozone depletion, could be found in the
midlatitude stratosphere when large storms inject water vapor high
into the stratosphere. During the Dynamics and Chemistry of the Summer
Stratosphere (DCOTSS) NASA ER-2 aircraft field campaign, magnitudes of
ClO capable of causing significant ozone depletion were not observed
within cold and wet air masses. Although large amounts of water vapor
were injected into the stratosphere by these storms, the air masses
lacked the chemical conditions necessary for chlorine activation to
cause significant ozone loss. Additionally, our modeling analysis of
data collected during DCOTSS indicates that the stratospheric
injection of sulfate, in an effort to mitigate global warming, could
increase the risk of chlorine activation in the midlatitude lower
stratosphere.
*Key Points*
Observations of ClO from the Dynamics and Chemistry of the Summer
Stratosphere mission show no evidence of heterogeneous chlorine activation
Chlorine activation was limited by the availability of inorganic
chlorine and the partitioning between the two major chlorine reservoirs
Enhancement of sulfate aerosol surface area would increase the
potential for chlorine activation in the midlatitude stratosphere
*Source: AGU*
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