Dear Geoengineering group,
This post is to complete what Dr. Schuiling (mineral carbonation) and
Dr. Salter (SRM by marine cloud brightening) said, and also to complete
several previous remarks made by Dr. Rau saying that we can’t talk of
CDR, ignoring ocean-based and/or abiotic negative energy systems +/-
ocean C storage, as the oceans represent 70% of the Earth’s surface!
Any ranking has to consider not only the well-known cooling parameters,
like SRM dependant albedo increase, CO2 depletion by assimilation, CO2
burial by BECCS but also the less discussed like methane depletion by
enhancing the atmospheric oxidation or the CO2 increase by SRM dimming.
Many examples of such alternative cooling parameters have been given by
Gaïa before during the numerous Ice Ages on Earth by dust-induced
cooling. Recent work shows that iron, an important component of
air-borne mineral dust, has at least 12 cooling effects and, to our
knowledge, is the only known one which acts both on the troposphere, the
continents, the oceans and the sediments:
Troposphere
Iron salt aerosols accelerates the depletion of GHGs like methane and
ozone and also the depletion of soot aerosols, by °Cl atom and °OH atom
emission, Fenton oxidation and photo Fenton oxidation.
Also iron salt aerosols (ISA) increase cloud albedo: photocatalytic
processes make the oxidic iron hygroscopic and enhance its iron
solubility. This enhances the aerosols transparency, makes it lighter
colored and provides it with an enhanced cloud condensation affinity.
SO2, NOx and organic emissions from natural sources or from
anthropogenic ones, generate sulfuric, nitric and organic acids. These
acids transform sea salt spray into HCl and accelerate photolytic °Cl
atom generation from ISA. Also NOx accelerates the photolytic °Cl atom
production by ISA.
Oceans
Iron salt aerosols activates the CO2 assimilation of phytoplankton by
micronutrient fertilization. Phytoplankton blooms emit DMS and
chloro-organic molecules. Their oxidation products increase the cloud
albedo.
H2SO4 (from DMS oxidation) further increases the chlorine ISA-induced
methane (and VOC) depletion by HCl generation from sea-spray.
Continents and sediments
Iron salt aerosols deposition acts as a micro-nutrient fertilizer on
plants suffering from chlorosis (iron deficiency) and increase the CO2
assimilation and the plant-induced CO2 weathering to HCO3-
The desert varnish build up by ISA induces methane and ozone-depletion.
Last but not least, methane consuming microbes within iron-poor
environments like peat bogs, wetlands, sediments and thawing permafrost,
are activated by ISA, and methane producing micro-organisms are
inhibited: the result is a reduction of the methane emissions from these
environments.
To our knowledge the Iron salt aerosols method proposed
<http://www.earth-syst-dynam.net/8/1/2017/esd-8-1-2017.pdf> is the only
yet proposed CE method which natural equivalent during the paleo
climates during the glacial times has been verified numerous times. This
verification includes all kinds of properties of the ISA method, not
only its many CE cooling activities, it includes its influences on the
marine and continental ecosystems.
The natural ISA method equivalent is the iron containing mineral dust
blown off in high emission rates from dry grounds with low vegetation
cover during the glacial time. This fruitful loess soil building dust
cooled up to 9 °C the global climate during glacial time climate by the
same mechanisms. Like the ISA method this natural cooling mechanism used
only the ingredients dust, sunshine and sea-spray to generate the
climate cooling.
In comparison to its natural equivalent, the “Iron salt aerosols method
<http://www.earth-syst-dynam.net/8/1/2017/esd-8-1-2017.pdf>” needs only
to stop further climate warming and a global climate cooling of 1 °C in
maximum.
The ISA method acts only within the lower part of the troposphere (not
in the stratosphere). This allows:
· regional restriction of the ISA method to regional parts of the
planet’s surface;
· easy process control by enlarging or reducing the ISA covered
surface
· immediate stop when the desired climate temperature has been
achieved
· reduction of possible negative influences on ecosystems (like
cloud albedo increase on regional parts of the Earth surface)
The iron salt aerosols method is cheap, feasible, and is already
occurring (some scientist think anthropogenic emissions of soluble
bio-available iron already have increased the marine productivity up to
50% in some regions, compared to pre-industrial era), it only needs to
be enhanced.
Like Dr. Eisenberger and Dr. Cady, we look forward for a scoring system
able to perform an independent and honest comparison of the ISA method,
towards other GHGR, CDR and SRM methods. Hopefully, the GeoMIP might be
able to perform it!
Best regards,
Franz Dietrich Oeste
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