Geoengineering: The Last Resort for our Planet?

Devika Kaul investigates the world of geoengineering, asking whether these sci-fi-esque ideas really have the potential to help mitigate climate change.

Written by: Devika Kaul

Art by: Cheng-Yu (Kou) Huang

Imagine a future in which sulfur oxides are pumped into the atmosphere, the sun is blocked by a giant shade and the oceans are covered in algae – all in the name of saving our planet. Some researchers believe that these methods of geoengineering could reduce the impacts of anthropogenic climate change.

Geoengineering is a broad term used to describe climate strategies that involve major intervention with the Earth’s natural environment. What makes these strategies unique is their ability to combat global warming without reducing greenhouse gas emissions. So theoretically, they could provide a ‘quick-fix’ solution to our climate problems, although most proponents only advocate their use alongside more traditional mitigation methods. Geoengineering can be loosely grouped into two categories: carbon sequestration (trapping carbon on earth) and solar radiation management (dimming the sun). Some of the more extreme strategies suggested range from fertilising the ocean, to creating a giant ‘space sunshade’ to divert the sun’s radiation from the Earth.

‘In the natural world, sequestration of CO2 occurs through photosynthesis, calcification of CO2 by phytoplankton, and mineralization in ground root systems. Can we enhance natural processes… or draw inspiration from nature as a starting point for artificial capture?’

These are the words of the US Secretary of Energy in 2009, Steven Chu (who also won the 1997 Nobel prize in Physics).  He was discussing Carbon Capture and Sequestration (CCS): a process which involves capturing the carbon released in the burning of fossil fuels and storing it underground. However, infrastructure and cost appear to have made any progress in CCS unlikely, so that many are now looking for alternative solutions.

One simple option is the preservation and expansion of natural carbon sinks, like forests and peat bogs. This brings benefits besides carbon storage: primarily that landscapes and habitats are protected. As well as these conservation schemes, which are virtually  risk-free and can hardly be classified as geoengineering, there are other unique ideas, like timber building construction. Carbon stored in wood is only released if the wood is not preserved, for example, if it is burned or allowed to decay. So, if timber construction were to take off, carbon would be stored in buildings and the demand for concrete would be reduced, which would have an important added benefit: the concrete and steel industries are responsible for more than 5% of carbon dioxide emissions. However, the pitfalls of this idea are far from trivial, namely habitat destruction and land quality degradation.  Furthermore, timber buildings carry a high risk of fires, especially in dense urban environments.

A still riskier carbon storage strategy is ocean fertilisation. Algae (aquatic organisms that can photosynthesise) can naturally sequester carbon in the same way as trees and other plants: by taking it in for use in photosynthesis. Ocean fertilisation would involve scattering substances in the water which encourage algal growth, making use of this natural carbon sequestering ability of algae.  However this strategy is extremely hazardous –  its risks include ocean acidification, ecosystem disruption and toxic tides, to name but a few.

When the Mount Pinatubo volcanic eruption in the Philippines spewed 20 million tonnes of sulfur dioxide out into the atmosphere, a temporary drop in global temperatures was observed. This inspired the concept of atmospheric sulfur injection: transporting gases – particularly sulfur dioxide – to the required altitude in aircrafts, airliners or even balloons. When released, the gas molecules combine with water in the atmosphere to form sulfuric acid, or other aerosols. Aerosols cause more of the incoming solar radiation to be reflected into space, meaning less radiative heating of the Earth. This would help reduce the warming effects of anthropogenic climate change.

However, as with all geoengineering strategies, there is very little knowledge of possible consequences. When attempting to alter the chemical composition of the atmosphere, unforeseen impacts are extremely likely. Take for example the development of chlorofluorocarbons (CFCs) as an alternative to the toxic refrigerants that were in use in the 1920s. As well as being non-toxic, CFCs were also chemically unreactive and non-flammable. However, it was later discovered that high in the atmosphere, ultraviolet radiation breaks CFC molecules apart. One of the by-products is chlorine, which can then react with ozone (O3) to form oxygen (O2). This process led to the depletion of the ozone layer, which has caused severe damage to the environment, by letting in harmful UV radiation. The ozone hole was only discovered in the 1980s, which shows how much time can pass before harmful consequences are even noticed, and how much damage can be caused in this period.

Some red flags have already been highlighted regarding sulfur injection – it has been suggested that the long-term effects of Mount Pinatubo have not been researched enough: for example, it  has been linked to increased drought in parts of Africa and disruption of the monsoon in Asia. As is often the case, this potential ‘side effect’ would have catastrophic consequences, likely affecting the poorer global South disproportionately.

Taking into account the complexities and risks of most proposed geoengineering methods, it is chilling to think that almost anyone with the resources could start experimenting with geoengineering, taking the fate of whole communities and ecosystems into their own hands. This has already been observed in Canada, where a self-appointed ‘geoengineer’ is known to have been experimenting with iron fertilisation of the ocean. If research is to take place, it is essential that there are strict regulations on implementation of these unusual methods, to prevent unqualified individuals from taking control.

As these examples demonstrate, for any extreme geoengineering scheme to be effective, a vast  amount of research would have to be carried out before any implementation can occur. This has led to most researchers being hasty to mention that geoengineering can only be a last resort solution. Professor Steve Gardiner of the University of Washington described it as ‘Plan Z’, as opposed to the ‘Plan B’ it is commonly referred to as. Others argue that even doing the research, albeit for the worst-case scenario, requires research funds that could be better spent on the safer and – some would argue – more responsible pursuit of renewable energy technologies.  


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