Geoengineering

One proposed side effect of geoengineering with stratospheric sulfate aerosols is sky whitening during the day and afterglows near sunset, as is seen after large volcanic eruptions. Sulfate aerosols in the stratosphere would increase diffuse light received at the surface, but with a non-uniform spectral distribution. We use a radiative transfer model to calculate spectral irradiance for idealized size distributions of sulfate aerosols. A 2% reduction in total irradiance, approximately enough to offset anthropogenic warming for a doubling of CO2 concentrations, brightens the sky (increase in diffuse light) by 3 to 5 times, depending on the aerosol size distribution. The relative increase is less when optically thin cirrus clouds are included in our simulations. Particles with small radii have little influence on the shape of the spectra. Particles of radius ∼0.5 μm preferentially increase diffuse irradiance in red wavelengths, whereas large particles (∼0.9 μm) preferentially increase diffuse irradiance in blue wavelengths. Spectra show little change in dominant wavelength, indicating little change in sky hue, but all particle size distributions produce an increase in white light relative to clear sky conditions. Diffuse sky spectra in our simulations of geoengineering with stratospheric aerosols are similar to those of average conditions in urban areas today.

Planetary Technology, a Canadian company, plans to dump 450 tonnes magnesium hydroxide into the sea in St. Ives Bay, Cornwall UK as part of an ocean alkalinity enhancement scheme, which raises concerns for the ‘Hands Off Mother Earth! Alliance. The experiment poses a potential serious risk to marine ecosystems and the Celtic Sea grey seal population.

Planetary Technology claims that the Ocean Alkalinity Enhancement (OAE) experiment will decrease the acidity of seawater and remove carbon. In theory, this would happen by adding magnesium hydroxide to the water in the bay, however this approach has not been proven.

Other concerns about the experiments by Planetary Technology raised by civil society include:

• The company has commercial interests, for example Planetary has sold CO2 credits to Shopify and Stripe without yet removing any CO2.
• Magnesium hydroxide occurs naturally as brucite, but the deposits are small. For industrial use, therefore, it is usually precipitated from sea water and then dried at high temperatures. > - This process requires so much energy that producing magnesium hydroxide may use more carbon dioxide than is captured through the enhanced weathering process.
• There are a number of concerns about the technical approach and safety of OAE. A recent article in Nature highlights the technical challenges around the technology.

The central tragedy in aquatic geoengineering is its superfluousness and cost. We already know how to combat climate change. Investing in alternative renewable energies, nuclear power including fusion, sensible environmental regulations and protections, and investments in public transit all work.

These all require sacrifice and political will. Geoengineering is a pie in the sky. It is a pipe dream, a perennial and seductive concept because it allows humanity to solve the problems of decarbonization, and energy transformation, without fundamentally altering the technology, behaviors, or structures which caused the problems in the first place.

Scientists are debating whether iron fertilisation can lock carbon into the deep ocean over the long term, and have raised concerns that it can irreparably harm ocean ecosystems, produce toxic tides and lifeless waters, and worsen ocean acidification and global warming.

The Saami Council’s opposition stems from a belief that geoengineering is the wrong way to approach climate change. “The way of thinking that humans are entitled to change and manipulate our surroundings has actually brought us into the climate crisis in the first place,” Larsson Blind said.

IT DOESN’T WORK: None of the technologies have a track record, all of them come with major risks and unknowns, and in some cases the effects would be obviously catastrophic.

WEAPONIZATION: Computer models show that geoengineering interventions can have regional winners and losers; to the extent that geoengineering successfully changes climate patterns in a predictable way, it will inevitably be weaponized.

DETRACTS FROM REAL SOLUTIONS: By promising a quick fix, geoengineering threatens to delay the implementation of a transition away from fossil fuels, and could redirect funding and investments away from real climate solutions. Some geoengineering proposals require vast amounts of energy, which means less climate-friendly energy for everyone else.

HUMAN RIGHTS AND BIODIVERSITY: Many geoengineering proposals require the intensive exploitation of vast amounts of land (in the case of BECCS, twice the size of India!). Those projects would inevitably displace millions of people and potentially wipe out entire ecosystems.

So you see, I’m not quite sanguine about our ability to engineer solutions to the many-headed hydra of a problem that is biophysical breakdown on this planet. Humans barely understand how nature works in many fundamental ways, including our own biology. We can’t engineer what we can’t understand. We probably can’t engineer biological systems at all. No, I have more confidence in nature fixing itself than in humans fixing nature.