Another Bonkers Idea To Moderate Climate Change: Iron Saturation of the Oceans

  That climate change is reaching  alarming levels is now obvious to all but the most purblind or brainwashed. This summer's epochal heat events, combined with 1,000-year storms and floods were exclamation points on the human imprints via enhanced CO2 infusion.  Much of this points to humanity hurtling toward the dreaded runaway greenhouse effects, e.g.

• Smoke-filled Air, Ochre Skies Provide Preview Of Life At Cusp Of Runaway Greenhouse...

In other words, we are already embedded in desperate climate times,

Energy Policy | Environmental Policy

The Later We Stop, The Worse the Result

by Thomas Neuburger | August 7, 2023 - 6:02am | permalink

— from God's Spies

Which recalls the saying "desperate times call for desperate measures."  Among these now, are proposals for geoengineering our planet to make adaptation at least feasible.  The latest submission, right out of Bonkersville, is to saturate the oceans with iron dust.  According to assorted techno-brainiacs, geoengineering the oceans by adding iron — in effect, fertilizing them — may offer the best, most effective and most affordable way not just to slow the march of global warming but to reverse its course by directly drawing carbon out of the atmosphere. The techno-magi insist the U.S. government needs to start testing it now, "before the climate system spins off into an even more disastrous state."

This geoengineering feat would in many ways replicate a natural process that has been underway for probably billions of years.  How so?  Iron-rich dust for eons and eons has blown off the land and into the seas, fertilizing algae and plankton. The more they grow, the more they convert carbon dioxide in the air to organic carbon, some of which eventually sinks to the watery depths.  Related studies suggest that this natural process of increasing iron-rich dust in the oceans takes so much carbon out of the atmosphere that at some point along the way it may have helped bring on the ice ages.   The graphic shown below shows the parallels between dust concentration, CO2 concentration and temperature variation:

Historic effect of iron dust seeding of oceans in limiting CO2

But energy-dependent humans have interrupted that natural cycle by their intense burning of carbon-laden fossil fuels.  Once the CO2 concentrations exceeded 280 ppm the ice ages halted. Not because of change in Earth's orbit, but because the degree of planetary heat trapping via the greenhouse effect was large enough to prevent it. Thus, though expanding deserts have sent more dust into the ocean, agricultural practices, i.e. to preserve topsoil,  have had the opposite effect: keeping dust out of the ocean and contributing to more warming overall.

Basically, in the past, the more iron dust there was in the ocean, the less carbon in the atmosphere and the cooler the average temperature on Earth. So why not have a dust redux and saturate the oceans with iron again?  There have already been a number of direct scientific experiments into this kind of geoengineering. From 1993 to 2009, about a dozen experiments used ships to deposit iron into ocean patches up to about 10 miles in diameter. The results showed that this approach could alter the exchange of carbon between the air and the sea, increasing the amount of carbon pulled from the atmosphere. They also showed the tremendous impact this approach could have at very low cost.

 One study found that each iron atom can catalyze reactions that convert up to 8,000 molecules of carbon dioxide to plankton or algae. Nonetheless, this kind of geoengineering has spawned two valid worries. First, activists fear such artificial interventions now will give fossil fuel industries a pass - and an excuse not to adopt cleaner technologies. Second, one can't ignore the inadvertent effects, including toxic algae blooms and impacts on commercially important fish species. In 2012 an entrepreneur added 100 tons of iron to the ocean and created a substantial short-term plankton bloom. Such blooms are already periodically raising ecological havoc in ocean waters off Florida - killing ocean life and emanating an awful, pervasive odor that has crippled tourism in areas.

Many scientists and policymakers worry about what could happen if commercial entities scaled up without government oversight. By 2013 a de facto ban on this research was in place. But that ban may not last longer. Given the catastrophic impacts of climate change around the world, as I've shown approaching a runaway tipping point, the undesirable consequences of ocean iron fertilization may be the lesser evil. 

Also, the oceans are themselves warming rapidly, equal to thousands of Hiroshima-scale A-bombs detonated each second. A recent study, published in Nature Climate Change, estimated that even under a low-emission scenario, more than half of marine species are at high or critical risk of extinction by 2100. Coral reefs are at risk from acidification and warming of the ocean surface.  This has all given the would -be geoengineers more energy to push their solutions and recall that iron seeding of the oceans isn't the first.

Some years back, Ezra Klein - writing in a NY Times piece - 

..

Opinion | Should We Dim the Sun? Will We Even Have a ...

ruminated on the prospect of "dimming the Sun" to spare humans the worst effects of global warming.  Klein wrote:

"The central theme of the Pulitzer Prize-winning author and journalist Elizabeth Kolbert’s new book, “Under a White Sky: The Nature of the Future.” is there is no going back. We will not return to a prelapsarian period where humans let nature alone. Indeed, as Kolbert shows, there is no natural nature left — we live in the world (and in particular, a climate) we altered, and are altering. The awful knowledge that our interventions have gone awry again and again must be paired with the awful reality that we have no choice save to try to manage the mess we have made.

 I wanted to focus on one that obsesses me: solar geoengineering. To even contemplate it feels like the height of hubris. Are we really going to dim the sun?

 We discuss the prospect of intentionally sending sulfurous particles into the atmosphere to dim the sun, whether “carbon capture” technology could scale up to the levels needed to make a dent in emissions levels."

Let's first  be clear there is no actual "dimming" of the Sun.  That would require altering our star's radiative opacity which is clearly beyond humanity's technological achievement level and may well be beyond any advanced civilization's as well.   We can express the basic equation of radiative transfer in the form:

dIn ds = -kn In + jn.

Where the transfer is attenuated by the first term on the right side with the opacity ( k_n )  defined in terms of the number density  n of absorbing particles and the absorption cross section  s_n:

kn = n sn

The reduction in solar radiation intensity  I_n  in situ is not what Klein is proposing.  Rather he is proposing an increase in the opacity of Earth's atmosphere by injecting billions of tons of sulphur dioxide into the upper atmosphere to increase cloud cover. In this case the radiative transfer equation that applies is:

 -dI/dt (1/k r ) = I – J

Where k is a mass scattering coefficient, r  is the molecular density (e.g. in cloud cover) and J is the vector source function for a specific intensity I.  Hence, if ample SO2 can be injected into the upper atmosphere then r  can be increased enough to diminish radiation intensity associated with heat  - in other words,  infrared radiation.  

While the idea looks neat on paper it would actually invite catastrophe and make conditions much worse.

Even if the mechanical- engineering  problems could be solved (including increased to the scale needed), it would still be a god-awful idea. For one thing, SO2 in the presence of the catalyst NO2 forms sulphuric acid, H2 SO4, and this can then generate acid rain. Do we really want ten septillion tons of acid rain descending on what remaining agriculture growth areas, farms remain in a greenhouse world? Not to mention raining on humans, with concentrations of pH in the range of 2-3? Ever had H2SO4 spill onto your skin in a chemistry lab?

Beyond that, SO2 at the given altitude needed for effect can further erode the ozone layer. In excess of a certain threshold, this erosion of protective ozone leads to much higher influx of ultraviolet radiation - more skin cancers, more blindness, etc.  In effect, Klein and Kolbert's "godlike" dimming solution merely creates more problems while attempting to solve the excess heat one from global warming.   

What appears to have escaped them is there is no real technological fix for our current predicament.  Short of hoping advanced aliens can turn the Sun into a cooler K-class star, the best and most realistic solution is conservation. Oh, and not letting the global population hit 10 billion!

See Also:

 "Superfreakonomics" - or Super nuts?

And:

https://keith.seas.harvard.edu/researchareas/solar-geoengineering