Geoengineering, the “deliberate large-scale intervention in the Earth’s natural systems to counteract climate change,” has been touted as a potential method for tackling the climate crisis but is it really the most viable solution for one of the most pressing and complex issues of our time?

What is Geoengineering?

Although there are numerous geoengineering technologies which have been proposed in recent years, these techniques mostly fall into two main categories: Solar Radiation Management (SRM) or Solar Geoengineering and Greenhouse Gas Removal (GGR) or Carbon Geoengineering.

Solar Geoengineering vs Carbon Geoengineering:

Solar geoengineering technologies aim to reverse the increases in global temperatures resulting from escalating greenhouse gas emissions by reflecting some of the sun’s incoming radiation back into space, effectively altering Earth’s albedo, whereas carbon geoengineering aims to actually remove greenhouse gas emissions from the atmosphere in order to reduce the greenhouse effect, whilst also combating ocean acidification

An expert committee of American scientists highlighted the need to distinguish between solar and carbon geoengineering. Whilst they agree that finding effective ways of removing greenhouse gas emissions from the atmosphere is “almost inevitable,” the use of solar geoengineering techniques is “irrational and irresponsible” unless utilised as a final resort. 

Although carbon removal techniques are generally recognised to be an essential part of preventing dangerous levels of greenhouse gas concentrations in the atmosphere, Scott Doney, a marine geochemist at Woods Hole Oceanographic Institution and committee member, raises the point that “you really need to spread your bets over a variety of techniques.”

Carbon geoengineering has been suggested by the Intergovernmental Panel on Climate Change (IPCC) as a potentially critical tool in the fight against escalating greenhouse gas emissions. 

Solar geoengineering as a solution to combating the climate crisis has faced widespread criticism and resistance amongst the climate science community because these technologies don’t address the root cause of climate change- human-induced greenhouse gas emissions- but instead masks the effects. 

Since many solar geoengineering techniques remain theoretical and their potential effectiveness based on model simulations, there is serious concern over the possible negative side-effects of these technologies since they are yet to be implemented in real-life scenarios. But is this criticism warranted?

Ultimately, many scientists believe that even considering solar geoengineering as a possible solution to the climate crisis provides governments with an easy way out and could cause them to take their eyes off the ball when it comes to reducing greenhouse gas emissions. 

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A study published last year aimed to clarify some of the uncertainties surrounding solar geoengineering by analysing what the effect on global climate would be if solar geoengineering was used to offset half of the warming produced by a doubling of CO2. Researchers found that under this scenario, the increase in tropical cyclone intensity caused by CO2 emissions could be offset by solar geoengineering. 

Furthermore, they concluded that temperature, water availability, extreme temperatures and extreme precipitation were all minimally affected by their simulations. Therefore, although this study did find some regional inequalities in the impacts of solar geoengineering, these are most likely overstated and the authors of the study rule out the claims that some regions would experience significant harm from these technologies.

Stratospheric Aerosol Geoengineering (SAG) is one of the most widely discussed solar geoengineering techniques. This would involve injecting sulphur dioxide into the atmosphere which, in theory, could mirror the effects of a large volcanic eruption and cool the Earth. During an eruption, sulphur dioxide is released into the atmosphere and upon combining with water forms sulfuric acid; it is these aerosols which reflect incoming solar radiation and effectively cool the planet.

There is overriding concern that whilst in theory, SAG could be a viable method for tackling the rise in global temperatures, it could lead to significant changes in rainfall patterns elsewhere, which could threaten agricultural practices and food supply.

Scientists are also concerned about the possibility of a dramatic increase in global temperatures if there is a sudden termination of aerosols being injected into the stratosphere. The issue with SAG is that it masks the problem of rising greenhouse gas emissions, which unless emissions reach net-zero, are inevitably going to increase.

Another reservation about SAG is that it wouldn’t solve other climate change effects such as ocean acidification, assuming greenhouse gas emissions aren’t tackled sufficiently. 

So is Geoengineering the Answer?

It is difficult to predict the exact role, if any, geoengineering will play in contributing to mitigating the effects of the climate crisis. However, what is certain is that it remains imperative that extensive research into these technologies continues now, and into the future, in order to determine the legitimacy of these possible solutions in the real world. 

Whilst in an ideal scenario the burning of fossil fuels would cease overnight, the bleak reality is that this will take significantly longer to achieve and the question is whether it will happen quickly enough to meet the ambitious 1.5C temperature target set by the Paris Agreement. Therefore, in addition to focusing on reducing human-induced emissions worldwide, geoengineering may well prove to be a critical ally in the fight against the climate crisis.