After there being, for years, a near-taboo associated with discussion and research on geoengineering, now there is a renewed interest in solutions to climate change problems that involve modifying the Earth’s system. However, the approaches that have been explored so far either fell short or exceeded the required parameters.
A collaborative study by researchers from India, China and the U.S. published in Geophysical Research Letters has offered a combination of two dominant methods — stratospheric sulphate aerosol increase and cirrus cloud thinning — to reduce global warming and precipitation rates to pre-industrial levels. The supercomputer simulation, based on the Community Earth System Model, suggests this as a possible way of dealing with planetary emergencies.
“[A]n accelerated warming in the future could result in planetary emergencies such as successive crop failures. Do we then have a plan to tackle this? That is where geoengineering comes in,” says Govindasamy Bala, from the Indian Institute of Science, who is part of this international collaborative research. He does not fail to emphasise that there must be a strict governance framework set up while exploring these options, as they involve ethical and moral questions.
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One of the well-studied methods proposed in geoengineering was to spray minute sulphate aerosol into the stratosphere. This would have the effect of reducing the warming to pre-industrial levels, but would also reduce the precipitation at a much higher rate than required to balance the effect of carbon dioxide. The other option proposed was cirrus cloud thinning. Since the cirrus clouds, which are at a height of 10 km above the Earth’s surface, also trap the heat, thinning them could cool down the Earth system. However, this reduces the rate of precipitation to less than the required amount.
The study suggests that a cocktail of these two approaches would change both temperature and precipitation at the same rate at which they are being increased by carbon dioxide; hence, the approach could, in principle, simultaneously restore both temperature and rainfall to pre-industrial levels.
According to Mr. Bala, the main advantage of geoengineering, when compared to, say, carbon sequestration, is that it costs less. “In the place of cost in the order of, say, $250 billion every year for direct methods, geoengineering could cost around $5-10 billion,” he estimates. There is also the problem of scale — after trapping billions of tonnes of carbon dioxide using the direct carbon sequestration methods, how does one transport and store it?
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This nascent research only underlines the need to achieve consensus on climate change mitigation.