If it were my headline it would read "worse than you might think" but it's Ars Technica's on top of an Ars Technia story so we'll go with it. October 13:
Solar geoengineering simulation shows what happens when geopolitics takes over.
When it comes to deciding the fate of the planet, Colleen Golja always thought science and reason would have a seat at the table. That was until one morning last September in London, when the climate researcher took part in the first in a series of war games. The goal: to prevent an uncontrolled global race to develop a technology aimed at cooling the planet but that comes with vast, unknown risks that could reshape life on Earth.
“I thought that would be such an easy thing. Like, we can all agree to do ethical research and make sure it’s for the better of all humans,” she told WIRED. “And boy, was I wrong.”
The simulation, titled Exploring Geopolitical Tipping Points and Climate Cooling Strategies, saw a couple dozen foreign-relations experts, scientists, military personnel, and former government officials from across the world convene in a meeting room at Queen Mary University of London. After making introductions over coffee and little yogurts, they sat at tables arranged in a square with the name of the country or organization each person was playing: national governments, climate NGOs and nonprofits, indigenous groups, and tech companies. Golja was assigned to provide technical advice to help participants make scientifically literate decisions.
The point of the game was to stress-test the world’s response to a group of prospective technologies known collectively as solar radiation modification. These technologies promise to reverse global warming by reflecting away a portion of the sunlight reaching Earth, for example by spraying particles of sulphur dioxide or some other manufactured substance into the atmosphere. The cooling effect of this kind of solar geoengineering is widely accepted. It would mimic the well-known impacts of large volcanic eruptions, which temporarily cool the planet by half a degree or more. But the fallout is less certain—and less equal. Some regions will suffer: Models predict drying in sub-Saharan Africa and more intense tropical storms in the Atlantic. The cooling effect would also last only as long as the geoengineering continued; after that the global temperature could shoot back up with wild and hard-to-predict effects.
Until recently, the idea of solar radiation modification was a speculative niche of climate science. That has changed fast. Private firms are exploring solar geoengineering as a commercial opportunity: Last year, a US-Israeli startup called Stardust Solutions raised $60 million, and in May it released details of a suite of new inventions it claims would give humans the ability to dial down the global temperature as desired. In August, Elon Musk, whose company SpaceX might be a candidate for delivering geoengineering interventions, threw his voice behind solar geoengineering, writing on X: “Space satellites to control temperature and massive geo-engineering will be needed or it will be game over.”....
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That snapback effect is just one of the arguments against any approach that requires constant inputs, whether the goal is dim sun or polar albedo or terraforming terra.
For some of the other reasons just have your supercomputer do a few million model runs to see what else can go wrong.
If, and we are not there yet but if adaptation and effect-mitigation do not increase the time available to formulate actual geoengineering solutions the safest approach is slow, incremental iron fertilization of the Southern Ocean to stimulate plankton growth, pull into the plankton biomass and then sequester it in the ocean depths either as detritus slowly sinking into the muck or as whale dung doing the sinking in a modified form.
"Saharan Dust Carries Iron That Feeds Life in the Distant Ocean"
Our preferred approach to geoengineering the carbon cycle, if one is deemed to be essential, is a gradual seeding of iron into the Southern Ocean to feed the phytoplankton and eventually sequester the carbon in the briny deep, either as sinking dead plankton cells or more probably as fish and whale poop.
But there's more to the story. If you prepare the iron to the plankton's taste you get a lot bigger effect.
From the American Geophysical Union's EOS, October 30:
A new study of seafloor sediments suggests reactions in the atmosphere convert dust-borne iron into forms more readily taken up by phytoplankton.
Windblown iron carried on dust particles from the Sahara travels long distances. The critical nutrient is ferried to plants in the Amazon and to phytoplankton in the Atlantic Ocean and elsewhere. But much of this iron is initially locked up in molecules that are not bioavailable—cells simply can’t use it.
New research published in Frontiers in Marine Science shows that the farther this iron travels on windblown dust, the more bioavailable it becomes because of chemical reactions it undergoes while in the atmosphere.
Iron is essential for some of life’s most basic processes, playing a key role in biomolecules responsible for photosynthesis, DNA repair, and more. It’s a key constraint on the growth of phytoplankton, the bedrock of ocean ecosystems and a major driver of the planet’s carbon cycle. Iron-rich dust from the Sahara can therefore have a tremendous impact on distant ecosystems.
“There are neat interconnections across huge scales of time and space,” said Vernon Morris, an atmospheric scientist at Arizona State University who was not involved with the study. Morris leads a project called AEROSE (Aerosols and Ocean Science Expeditions) that has been following Saharan dust storms across the North Atlantic since 2004.
Connecting Air and Ocean
Making the chemical link between what happens to iron-rich dust in the atmosphere and what happens to it in the oceans has been challenging. Researchers have measured total iron levels in ocean floor sediment cores, but this approach doesn’t consider whether that iron was in forms that organisms can use, said Timothy Lyons, a biogeochemist at the University of California, Riverside, and a coauthor of the new study....
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Related:"Searching for the Dust That Cooled the Planet"
This is why you want to be careful with the geoengineering proposals. Some links after the jump....
Plankton Week: “Give me a half tanker of iron, and I will give you an ice age.”
The headline quote is from oceanographer John Martin during a 1988 lecture at Woods Hole Oceanographic Institution. Here's NASA's Earth Observatory archive page on the statement.
It is a bit of an exaggeration, you may need ten of those Valemax bulk carriers, currently the second largest ships in the world at 400,000 dwt (Euronav's two TI oil tankers at 441,000 dwt are bigger), to make an environmental change but what a change it would be. The orders of magnitude of carbon the iron-fed plankton would sequester are almost mind-boggling:
...Martin gathered the results of the incubation experiments and laid out the evidence in support of the Iron Hypothesis together with some back‐of‐the‐envelope calculations and presented his findings at a Journal Club lecture at Woods Hole Oceanographic Institution in July of 1988. He estimated that using a conservative Fe : C ratio that 300,000 tons of iron in the Southern Ocean induce the growth of phytoplankton that could draw down an estimated two billion tons of carbon dioxide. Then, putting on his best Dr. Strangelove accent, he suggested that “with half a ship load of iron….I could give you an ice age.” The symposium broke up with laughter and everyone retired to the lawn outside the Redfield Building for beers (from Chisholm and Morel, Editors, preface to: What controls phytoplankton production in nutrient‐rich areas of the open sea? Limnology and Oceanography, 36, 8 December 1991).
As repeated in "John Holland Martin: From Picograms to Petagrams and Copepods to Climate"
—Bulletin of Limnology and Oceanography, Wiley. 25 March 2016
....Coming up tomorrow, the Pope, and a Vancouver stock promoter.
Our series thus far:
October 27
Plankton Week: "Metal deposits from Chinese coal plants end up in the Pacific Ocean, research shows"
October 26
"Plankton Bloom Heralded Earth’s Greatest Extinction"
