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Business News/ Opinion / Views/  The temptation of a sun screen to cool the planet

The temptation of a sun screen to cool the planet

It’s a controversial idea that would need a global consensus for a go-ahead. Even if it’s only a last resort, India must work out the risks and benefits for itself to adopt a firm stance on it

Photo: iStockPremium
Photo: iStock

Expectations of the 26th United Nations Climate Change Conference (CoP-26), to be held this autumn in Glasgow, have risen after the intergovernmental panel’s latest report on the crisis served us a warning on how badly off-target we are in doing the least that must be done to keep our planet from going past its danger mark—reckoned to be an average temperature of 1.5° Celsius above pre-industrial levels. The world’s ability to act in unison, unfortunately, remains in doubt. Yet, as the effects of global warming worsen, we may be forced at some point to confront a yes-or-no decision so critical that it can only be taken by consensus: whether or not to throw a sun screen around the globe in a last-ditch attempt at fending off disaster. This option scarcely finds mention in the panel’s 4,000-plus page report, a sign perhaps of how controversial this idea of ‘solar geo-engineering’ is. But if saving the earth is a must-do, then it cannot be kept off the table. This calls for a risk-benefit analysis duly informed by science.

In conceptual terms, the proposal is simple. If the earth is made to reflect some of the sun’s heat, we could cool it down or counter the thermal impact of methane and carbon emissions. Huge mirrors placed in orbit had been an early suggestion, but a far less clunky way out would be to deploy soft interventions. To bounce solar rays off our globe, we could possibly brighten natural clouds, done by spraying oversea formations with saltwater to squeeze water out of them. This could accompany an exercise to reduce cloud density so that they trap less long-wave radiation, even as ships churn up seafoam to compensate for our shrinking polar caps (which, being white, act as natural reflectors). Since these ideas have limitations of scope and calibration, attention has turned to a ‘killer app’: the proposition that we lace our stratosphere with additional reflective aerosols to keep out exactly as much sun as we need for a recovery. Unlike cloud and ocean manipulation, an aerosol screen would be a global project, not a patchy one. Nor would it meddle as much with our weather patterns, ocean currents and marine life, being so far up in the sky. An elevation that high is needed, above all, for safety. The sulphate aerosols that act as coolers are harmful. While we go about clearing the air of these, they could yet serve a worthy purpose at the upper reaches of our atmosphere. Alas, what could go wrong and the costs thereof are not yet clear. What if an aerosol-release error combines with a wild chain reaction up there to stir up even more havoc down here? The odds of such a shock scenario need to be worked out and debated. Only then can such a plan’s potential for heat-relief be weighed against its risks, which may include a slackening off on carbon-neutrality as a goal. Unmet emission targets could spell uncertainty, deter clean investments and expose us to apocalyptic outcomes.

It should be self-evident that nobody has the right to modify the planet’s gaseous make-up without everyone else’s explicit approval. But this complexity must not disqualify the sun- screen option. Even if it’s only a last resort, a reflective shield must not be kept off the global agenda for multilateral talks. Perhaps CoP-26 could discuss it. India, meanwhile, should study the option on its own to arrive at a stance shaped by scientific findings. We have plenty at stake, as current heat caps are not up to the task, and dicey decisions may lie ahead.

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Published: 15 Aug 2021, 09:05 PM IST
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