Huh. Of all the emergency, if we really, really-have-to-do-it-geoengineering methods, this is the one we lean toward. Links below.
From Hakai Magazine, January 13:
The controversial geoengineering technique can defer, at best, a few years’ worth of emissions. And that’s ignoring the potential side effects.
....MUCH MORELast year, global carbon emissions from burning fossil fuels reached an all-time high. As the world heats up, many influential bodies—such as the United Nations Intergovernmental Panel on Climate Change, the governments of China and the United States, and especially fossil fuel companies—are calling for the development of carbon removal technologies. These techniques pull carbon dioxide, a potent greenhouse gas, out of the air or water and lock it away in an inaccessible form. At a big enough scale, these technologies can theoretically counterbalance emissions and help cool things down—or at least slow the rate of warming.
That’s why, in November 2021, Edwina Tanner, a marine scientist at the Australia-based biotechnology company Ocean Nourishment Corporation, dumped a mix of nutrients from a boat into the water in Botany Bay, on the south side of Sydney, Australia. As waves rocked the craft, currents pulled the red-dyed slurry in every direction, permeating one tiny patch of the world’s largest carbon sink: the ocean.
The limiting factor for the abundance of life at the ocean’s surface is often the availability of essential nutrients like iron, nitrogen, and phosphorus. So when a glut of nutrients arrives in the form of volcanic dust, wildfire ash, water upwelled from the deep, or a lab-made mixture, the sudden bounty allows tiny photosynthesizing phytoplankton to flourish. Like plants, these single-celled organisms use sunlight and carbon dioxide as fuel. The important thing for those concerned with climate change is that when these phytoplankton die, some of them sink, dragging the carbon in their bodies to the seafloor where it becomes trapped.
Oceanographer John Martin first proposed the idea of manipulating the ocean’s nutrients to store carbon in the late 1980s. There have been a few experiments since, but in general, says Tanner, getting real-world data on how well nutrient fertilization works is incredibly challenging. The public doesn’t have a big appetite for large-scale climate experiments at sea, she says.
The last large-scale attempt was a decade ago and, to Tanner’s point, it was spectacularly controversial. So in recent years, scientists have instead turned to laboratory work, computational models, and smaller field trials to better understand ocean nutrient fertilization. Modeling published in 2017, for instance, suggests that adding nitrogen and phosphorus to the ocean could lock away up to 1.5 gigatonnes of carbon per year from the atmosphere.
Tanner and her team at Ocean Nourishment Corporation are among the many scientists striving to learn more. Although she hopes to run larger field experiments, it’s difficult to get permission from the Australian government for trials exceeding 2,000 liters of the nutrient mixture. In the Botany Bay experiment, the researchers added only 300 liters of their nutrient mix. Working with such small quantities makes calculating the consequences very challenging. To circumvent the restrictions, they’re building a bioreactor to test how different mixes of nutrients stimulate phytoplankton growth and affect the rate of carbon storage.
Other researchers, too, are digging into nutrient fertilization. In 2023, for example, Joo-Eun Yoon, an applied mathematician at the University of Cambridge in England, conducted experiments with a team in the Arabian Sea off Goa, India, to find out how to best deliver nutrients to the ocean. Maximizing carbon storage, it turns out, is not as simple as just dumping nutrients overboard.....
Previously:
"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"
And many many more going back to Russ George and Planktos in 2007.
