Guest essay by Eric Worrall

Climate scientists are hoping the leaders of poor countries desperate to stop their people suffering climate hardship will fund their stratospheric sulphate injection experiments.

Rich countries aren’t stopping climate change. Can poor nations save themselves?

By James Griffiths, CNN
Updated 0159 GMT (0959 HKT) September 10, 2019

CNN)
Tall and stony-faced, with a long and bitter history of fighting for democracy, Tongan leader Akilisi Pōhiva is not someone you’d expect to break down in tears at an intergovernmental summit. 

At a meeting of Pacific leaders last month in the tiny island nation of Tuvalu, other attendees saidPōhiva was overcome with emotion as he tried to secure Australian Prime Minister Scott Morrison’s support for a more forceful approach to tackling the climate crisis.

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Should developing countries take action? 

So far, efforts to tackle the climate crisis have largely focused on international agreements to reduce emissions, ones that have been — by and large — profoundly unsuccessful in doing so. 

While the most effective way of lowering global temperatures is to reduce emissions, this is something that requires a global response, unlike some geoengineering methods which could be carried out — at least in theory — by a single country or group of countries. 

“Unfortunately, the most environmentally responsible way is also the most politically difficult,” Ken Caldeira, a climate scientist at the Carnegie Institution for Science, said last year. “If there’s a leader of a country whose people are starving, and they think by injecting some particles in the stratosphere they can feed their people and alleviate suffering, the political pressure to do that is going to be intense.“

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Read more: https://edition.cnn.com/2019/09/09/health/climate-change-geoengineering-asia-intl-hnk/index.html

It seems implausible that leaders of poor countries will obtain the cash to fund a major geoengineering experiment, but what would happen if they did?

The result could be a global catastrophe. A study of natural sulphate injection events, volcanic eruptions, made the surprising discovery that plants need sunlight. Injecting sulphate into the atmosphere crashes crop yields.

Estimating global agricultural effects of geoengineering using volcanic eruptions
Published: 08 August 2018
Jonathan Proctor, Solomon Hsiang, Jennifer Burney, Marshall Burke & Wolfram Schlenker 

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: https://www.nature.com/articles/s41586-018-0417-3

I’m really concerned about the stratospheric sulphate injection idea, its unlikely that anyone will attempt this at sufficient scale to cause problems, but people shouldn’t even be trying to do this; the consequences of injecting sulphate on a large scale seem far worse than any “damage” which might accrue from a degree or two of warming.