Solar Geoengineering

With the number of extreme weather events that occurred in 2023, there is a new urgency around the need to find alternate and innovative solutions to the problem of climate change. One easy option is solar geo-engineering - that can be implemented by startups that raise donor funds to send up balloons carrying sulphates. That said this is not without its fair share of concerns. Not the least of which is uneven cooling and the impact on monsoon patterns in India.

This article was first published in The Mint. You can read the original at this link. Archived.

On 29 September 2023, rainfall broke all previous records at the John F. Kennedy Airport in New York. The National Weather Service warned of potentially life-threatening flash floods in poorly drained areas, and the city’s subways literally cracked at the seams in some places, with torrents of water gushing from walls. Videos of the city showed waterlogged homessubmerged cars and people being rescued in boats. The world’s most privileged city had been brought to its knees by extreme weather.

Catastrophic Weather

But the New York City episode was only one in a series of catastrophic weather events this year. In California, the Burning Man festival that is held in the middle of a desert was turned into a giant clayey mud-pit so utterly impossible to traverse that festival-goers were advised to shelter in place till they could be rescued. The Hong Kong Observatory recorded in just one hour more rain than ever before, as a result of which the posh streets of that cosmopolitan city were transformed into raging rivers. Europe faced extreme heat and Xinjiang in China recorded its highest temperatures yet, while wildfires in Canada burnt over 40 million acres of forest. If we ever needed evidence that climate and weather patterns have changed, this year’s events provide it.

I have, in previous articles in this column, discussed some possible solutions—ways by which we might reverse some of these harms of our own making. One solution is solar geo-engineering—the process by which the reflectivity of the upper atmosphere is increased so that, instead of warming up the earth, the rays of the sun are simply deflected away.

Simple Solution

This, as it happens, is an idea that is relatively easy to implement. All it would take is the release of sulphur dioxide in the upper atmosphere where, on coming in contact with water vapour, it will form suspended droplets that act like tiny mirrors, reflecting sun rays back into space. The cost of doing something like this would be, according to a recent article in the Scientific American, roughly $18 billion a year for each degree of cooling achieved. When compared with the alternative—the cost of removing billions of tonnes of carbon dioxide from the atmosphere needed to keep global warming under 1.5° Celsius above the pre-industrial level—it is clearly the more cost-effective solution.

The trouble is that stratospheric injections of sulphur dioxide can affect weather patterns all over the planet. A rise in the concentration of stratospheric aerosols could lead to uneven cooling that, while it might cool down tropical zones, could result in a small but unacceptable increase in temperature around the poles. In real terms, this would mean that even if we successfully mitigate extreme weather around the equator, we could, at the same time, be accelerating the rate at which permafrost and sea ice melts at the poles.

These unintended consequences could also vary depending on how the geo-engineering is carried out. For instance, studies at the Indian Institute of Science suggest that injections carried out at the equator would likely result in aerosol particles being spread across the northern and southern hemispheres in such a way that there will be very little impact on monsoon patterns in India. If, however, these injections take place at high northern latitudes—as might be necessary if we want to slow down Arctic warming—they are more than likely to have a significant impact on our monsoon precipitation, potentially shifting its band southward by 150km and reducing, as a result, the country’s summer rainfall by as much as 29%.

Make Sunsets

Given how easy it is to inject sulphur dioxide in the upper atmosphere, there is little to stop countries—or private citizens even—from taking matters into their own hands. In February this year, US-based solar geo-engineering startup Make Sunsets did just that. By burning store-bought sulphur, it created sulphur dioxide gas, which it used to fill a balloon. After topping it off with a little helium to float, the balloon was released into the sky. It was monitored as it floated higher and higher into the sky till it eventually exploded, releasing the gas into the upper atmosphere.

Make Sunsets had raised funds for its experiment by convincing donors that every $10 they were contributing would pay for the release of one gram of sulphur dioxide—enough, it claimed, to offset the warming effects of a metric tonne of atmospheric carbon dioxide for a year. After that initial shot, it launched three more such balloons, and has plans for a thousand more. For its supporters, this is an inexpensive way to ease their conscience. The small amount they contribute will, they are assured, help create a massive protective dome around the earth, which, by reflecting heat, will help compensate for the many tonnes of carbon they have emitted over their lives. They will, as a result, help mitigate the worst extremes of climate change and make an impact where even governments have failed.

Yet, no one should attempt to re-engineer the planetary weather system without properly evaluating the direct as well as unintended consequences of such actions. Even if these measures help ameliorate weather conditions around the location where the injection exercise is aimed, there is no saying what effect it might have on conditions somewhere else on the planet.

If geoengineering is the path we are going down, we would do well to at least co-ordinate our efforts.