- Spraying aerosols in the stratosphere, especially radiation-scattering ones such as sulphates, does have a cooling effect. However, scientists warn us about its unintended consequences
- There is some reason to believe that the ‘summerless year’ that followed the eruption of Mt. Tambora in 1816 inspired the novels Frankenstein and The Vampyre.
- A sufficiently powerful volcanic eruption can spew sulphates and other aerosols into the stratosphere, cooling the air there. This fact has motivated people to artificially do the same thing to slow global-warming.
Moon dust coolers
- A recent media buzz on this front is from a paper published in the journal PLoS Climate on February 8.
- Researchers from the U.S. have proposed that billions of tonnes of dust can be launched from the moon to a point in space where the earth’s and the Sun’s gravitational fields cancel each other out. The dust will thus be ‘parked’ there, casting a shadow on earth and dimming sunlight to offset carbon emissions.
- While aerosols in the stratosphere, especially radiation-scattering ones such as sulphates, do have a cooling effect, let’s not forget the consequences of the 1816 eruption.
- The ‘cool’ summer sent crop yields plummeting worldwide, leading to disease and starvation. Many climate models have confirmed that dimming the amount of incoming sunlight with stratospheric aerosols will have similar outcomes.
- Some studies have argued that the resulting drought won’t be as harmful and that the GDPs of most countries will be positively affected by such solar radiation management (SRM).
- But even state-of-the-art climate models are skilled only at simulating the temperature response to changes in solar radiation.
- These projections are also best at the continental scale and not at the regional scale, which matters when it comes to heatwaves and drought.
Concerns about SRM models
- Climate models are still woefully inadequate at estimating the precipitation response to solar radiation perturbations at all scales.
- Any projections related to changes in rainfall, as a result of blocking sunlight, will be highly uncertain.
- Therefore, concluding that SRM won’t have unintended consequences in the form of drought and crop losses, based on models that can’t reliably predict precipitation, would be foolhardy.
- Many natural as well as social scientists have expressed grave concerns about SRM science and governance.
- Compensation for the accidental outcomes of SRM will be more contentious. The University of Oxford and the Asilomar Conference have proposed some guiding principles for attempts to geoengineer the climate.
- These include that those involved must clearly and explicitly report the science and technology of these approaches along with their consequences; deployment and monitoring, verification, and reporting mechanisms should be democratic and inclusive; and stakeholders must agree on compensation mechanisms for any harm beforehand.
- Finally, a major caveat of the aerosol-loading approach is that there will be a rebound effect once spraying stops and the aerosols are washed out of the atmosphere.
- So, when the temporary cooling effect is on, we must still reduce emissions. If we don’t, the cooling effect will end and the heating period will recommence.
SOURCE: THE HINDU, THE ECONOMIC TIMES, PIB