Essay by Eric Worrall

Imagine a climate initiative so crazy even Californian greens reject it?

FAILURE TO COMMUNICATE

Geoengineering could be crucial in the fight against climate change. But first scientists need to learn how to talk to the public about it

3 APR 2025
2:00 PM ET
BY REBEKAH WHITE

When Marilyn Ezzy Ashcraft, mayor of Alameda, California, scrolled through The New York Times on a Saturday morning in April 2024, a story about a controversial experiment caught her eye. Researchers from Washington state were trialing a machine that looked like a big snow cannon, which they hoped could one day be used to brighten clouds to reflect more of the Sun’s rays. They’d been spraying tiny salt particles into the air over the San Francisco Bay.

At first, Ashcraft wondered which neighboring town was hosting the test. But as she read, she was shocked to learn that the researchers were conducting their experiment right there in Alameda.

Ashcraft texted her acting city manager, who was equally surprised. The story revealed that the researchers had kept the test a secret to limit protests. “It wasn’t just an oversight that they forgot to tell the city,” Ashcraft says. “They chose not to.” Concerned about the safety of the test, city staff investigated. Though a report concluded it was harmless, the council eventually voted to ban it, discomfited by the researchers’ lack of transparency.

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FORGOING PUBLIC engagement has already had fatal consequences for solar geoengineering projects—with ramifications for the entire field.

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Read more: https://www.science.org/content/article/geoengineering-fight-climate-change-if-public-can-convinced

Geoengineering is wrong on so many levels. The side effects of many proposed schemes are so outrageous they should never see the light of day.

Estimating global agricultural effects of geoengineering using volcanic eruptions

Published: 08 August 2018

Jonathan Proctor, Solomon Hsiang, Jennifer Burney, Marshall Burke & Wolfram Schlenker

Nature (2018)

Solar radiation management is increasingly considered to be an option for managing global temperatures, yet the economic effects of ameliorating climatic changes by scattering sunlight back to space remain largely unknown. Although solar radiation management may increase crop yields by reducing heat stress, the effects of concomitant changes in available sunlight have never been empirically estimated. Here we use the volcanic eruptions that inspired modern solar radiation management proposals as natural experiments to provide the first estimates, to our knowledge, of how the stratospheric sulfate aerosols created by the eruptions of El Chichón and Mount Pinatubo altered the quantity and quality of global sunlight, and how these changes in sunlight affected global crop yields. We find that the sunlight-mediated effect of stratospheric sulfate aerosols on yields is negative for both C4 (maize) and C3 (soy, rice and wheat) crops. Applying our yield model to a solar radiation management scenario based on stratospheric sulfate aerosols, we find that projected mid-twenty-first century damages due to scattering sunlight caused by solar radiation management are roughly equal in magnitude to benefits from cooling. This suggests that solar radiation management—if deployed using stratospheric sulfate aerosols similar to those emitted by the volcanic eruptions it seeks to mimic—would, on net, attenuate little of the global agricultural damage from climate change. Our approach could be extended to study the effects of solar radiation management on other global systems, such as human health or ecosystem function.

Read more (paywalled): https://www.nature.com/articles/s41586-018-0417-3

Plants need sunlight. Any alleged benefit of cloud brightening to reflect more sunlight into space would be more than overshadowed by the negative impact of depriving plants of sunlight.

We don’t need a scientific study to confirm this, because it has already happened. In the year 536 AD, a catastrophic volcanic eruption caused widespread crop failures in the Mediterranean, because the cloud brightening effect of the volcano disrupted weather and weakened plant growth.

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The Roman historian Procopius recorded in AD 536 in his report on the wars with the Vandals, “during this year a most dread portent took place. For the sun gave forth its light without brightness… and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear”.^[5][6]

In 538, the Roman statesman Cassiodorus described the following to one of his subordinates in letter 25:^[7]

• The sun’s rays were weak, and they appeared a “bluish” colour.
• At noon, no shadows from people were visible on the ground.
• The heat from the sun was feeble.
• The moon, even when full, was “empty of splendour”
• “A winter without storms, a spring without mildness, and a summer without heat”
• Prolonged frost and unseasonable drought
• The seasons “seem to be all jumbled up together”
• The sky is described as “blended with alien elements” just like cloudy weather, except prolonged. It was “stretched like a hide across the sky” and prevented the “true colours” of the sun and moon from being seen, along with the sun’s warmth.
• Frosts during harvest, which made apples harden and grapes sour.
• The need to use stored food to last through the situation.
• Subsequent letters (no. 26 and 27) discuss plans to relieve a widespread famine.

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Read more: https://en.wikipedia.org/wiki/Volcanic_winter_of_536

Who in their right mind would want to deliberately invite the risk of such a disaster? Obviously I don’t think releasing a few kilos of sulphur from a drone will lead to any kind of disaster, but the warning from nature is clear – repeating these experiments at scale could trigger a global famine.

There is no evidence the mild global warming we are experiencing or will in the future experience in any way justifies inviting such risks.

There is a good reason Geoengineers have to hide their work from the public – the public understands the risks, and strenuously objects to such recklessness.