What is geoengineering and should we try it?

Materials World magazine
5 Jan 2016

Until recently, the idea of engineering the earth’s climate to reduce the impact of global warming was widely regarded to be closer to the realm of mad scientist than real academic study. But, increasingly, it’s making the headlines. Rhiannon Garth Jones finds out more. 

More than one volcanic explosion has injected such high amounts of sulphur dioxide into the stratosphere that the sunlight reaching the earth's surface was temporarily reduced, lowering the global temperature. The eruption of Mount Tambora, Indonesia, in 1815, and of the Philippines' Mount Pinatubo, in 1991, both reduced temperatures around the world by 0.4–0.7°C. As world leaders try to agree on measures to stop the global climate rising by more than 2°C, the idea that we could artificially create a similar temperature drop is understandably appealing. 

However, the year following Mount Tambora’s explosion was known as ‘the Year Without Summer’ in the northern hemisphere and subsequent crop failures from North America to Bengal caused the worst famines of the 19th Century, according to a study by Clive Oppenheimer, Professor of Volcanology at the University of Cambridge, UK. Clearly, any method that scientists come up with to artificially replicate the effects of large-scale volcanic eruptions on global climate will have to identify and mitigate the consequences.

The time is now

This type of fiddling with the Earth’s climate is often referred to as geoengineering. A wide range of options have been proposed over the years, many inspired by existing natural phenomena, and the approach remains controversial. But the growing consensus about the likely increase in global temperatures and the subsequent impact has lead to a number of high-profile calls for greater research into possible solutions. Geoengineering has been pushed further into the spotlight following the recent COP21 conference in Paris, the focus placed on the issue by the Pope in 2015 and the acknowledgement by leaders of developing countries, such as India’s Prime Minister Narendra Modi, of their unwillingness to sacrifice an improving quality of life by reducing their carbon emissions. More and more, it seems, we are willing to acknowledge that our carbon emissions are contributing to rising temperatures, without a concurrent willingness to take action. Geoengineering aims to fill that gap between our awareness and action. If we can (relatively) cheaply prevent the predicted future climate without altering our quality of life, its supporters argue, why don’t we try?  

The arguments on both sides suffer from the same problem – we just don’t know enough to present a comprehensive case, as the few previous experiments haven’t released their results. But, as research and funding in this area gains momentum, we are starting to get an idea of what some of the different approaches might be and the main ones break down into two broad groups – solar reflection and carbon capture.

Reflecting the sun

The cooling effect caused by volcanoes is due to the particles of sulphur dioxide spewed out in the eruptions, which reflect the incoming rays of sun. This usually lowers the Earth’s temperature for around a year, though the effect can last up to five. The particles eventually fall, although the acid rain they create is not considered alarming. We could spray sulphur particles precisely, maximising the effect by reflecting more light for longer.

There are obvious pitfalls to this approach, as well as ones that we can expect further research to reveal. Firstly, the cooling effect isn’t permanent, so we would have to spray continuously to keep the temperature at the same level. If we didn’t, and the artificial shield created by the sulphur dioxide disintegrated suddenly, the subsequent rise in temperature could cause instant and serious problems, particularly if nothing was done to reduce emissions in the meantime. Secondly, we don’t know how precisely we could manage the reduction – a few tenths of a degree lower than intended and we could end up in a decade of ‘no summer’, devastating crops and altering weather patterns. 

This technique might be used in small, targeted ways – cooling a small section of ocean in the right place could limit the severity of a hurricane, for instance, or as a drastic measure when faced by an equally drastic event, such as a breakdown of the Indian monsoon.

David Keith and James Anderson, both professors at Harvard University and the chief administrators of Bill Gates’ Fund for Innovative Climate and Energy Research (Ficer), have been conducting research into solar reflection for years. The two stratospheric scientists are currently hoping to get support from NASA to launch a helium balloon, at an estimated cost of around US$10m, carrying sulphur and water vapour 20,000 metres into the atmosphere to spend a day monitoring their interaction with the ozone – previous research suggests that it will react with chlorine in the atmosphere, resulting in damage to the ozone. Keith and Anderson believe the impact will be less than a commercial airline flight. In the absence of many other such studies, it is hoped that it will contribute towards a structure governing similar research in the future.

Keith acknowledges the dangers of solar geoengineering, publicly stating, ‘I don’t necessarily believe we should do it. There are very legit arguments that we shouldn’t. But I think fundamentally, at this point, I’m an advocate for taking it seriously and doing serious research […] because it potentially has large benefits. That’s not crazy.’

Removing the issue

The other main approach to this issue is capturing carbon, an area of research that has seen much greater coverage in recent years, including in Materials World. Carbon capture could allow us to reach a ‘net zero’ status, without reducing our use of fossil fuels and possibly without the same consequences as solar reflection.   

The UK has been leading the way in this research, with two major carbon capture and storage (CCS) demonstration projects using post-combustion amine capture and oxyfuel combustion, being developed at Peterhead, Scotland, and Drax, north Yorkshire, over the past few years. However, the Government funding for these projects was withdrawn in the Autumn 2015 budget (see page 12 for more information). Shell, which was one of the remaining candidates for its Peterhead project, announced its disappointment, stating the technology ‘has the potential to bring huge value to the UK, both in terms of immediate emissions reductions and developing knowledge for the benefit of a wider industry’. Such a case highlights the problems geoengineering faces across the board – while some people are excited by the possibilities, there is too little funding available for the research to answer the many questions about each approach’s consequences.

Post-combustion amine capture and oxyfuel combustion are not the only methods of removing carbon from the atmosphere. One promising area is ocean-fertilisation, where nutrients such as iron, nitrogen and phosphorus are added to the ocean to increase marine food production and absorb carbon dioxide. The basic aim of ocean fertilisation is to increase the stocks of phytoplankton, which form the basis of the marine food chain and are found in extremely high concentrations – called a phytoplankton bloom – in ocean areas that are rich in nutrients, particularly iron and nitrogen. Phytoplankton absorb carbon dissolved in the ocean for photosynthesisation before, if uneaten, sinking to the deep ocean. In theory, significantly increasing the concentrations of phytoplankton would capture more carbon as well as improving sustainable fisheries in those areas. Iron is preferred to nitrogen and phosphorus because it has the highest potential for sequestration per unit mass added. It has been argued that, in principle, this approach is no different to the way we have expanded the nitrogen cycle in soil by the mass use of fertilisers, although the speed of the process would certainly be faster. 

One experiment in ocean fertilisation was conducted in 2012, 300km off the west coast of Canada’s Queen Charlotte Islands, when the Haida Salmon Restoration Corporation, funded by an indigenous tribe in British Columbia, added around 100 tonnes of iron sulphate across 5,000km2 of an ocean eddy in the Pacific. The corporation and its main advisor on the project, Russ George, focused heavily on the carbon capture value before the work began, as well as the likelihood of improving the production of salmon in the area. In 2013, the salmon runs rose from 50 million fish to 226 million and the experiment allowed NASA to collect images of the successful phytoplankton bloom, giving a much greater idea of the consequences of ocean fertilisation.

Looking forward

The Haida Salmon Restoration Corporation experiment remains controversial and is an excellent case study for the issue of geoengineering. The action was funded by a demographic that is likely to disproportionately suffer the impact of any climate change, without the approval from the Canadian Government, it may have ignored UN protocols on marine dumping and, while it has had initially promising results, it may well have unforeseen negative effects. The possibility that other affected groups and individuals might take similar action is a major concern, especially when the promised results are so exciting.   

Michael Thompson, Managing Director for the Forum for Climate Engineering Assessment, believes that we are not realistically at the stage where we can have a proper debate on the topic, but that ‘it is time to bring this conversation out of the closet. The best way forward is to have an open, robust conversation about all the potential strategic responses to climate change that take into consideration the voices of the most vulnerable to climate impacts, those with the most to gain, and the most to lose, from any potential deployment of climate engineering technologies.’ 

For that conversation, we need to know more about those technologies that look most viable, meaning we now urgently need more research. If geoengineering can give us time to change our carbon emissions without drastically reducing our quality of life, we surely want to know. Similarly, if attempts to engineer the ocean, the atmosphere, or any other part of our world might lead to catastrophic results for the planet and its population, we need to know before any large-scale action is taken. Geoengineering remains neglected by much of the serious academic community, but we need to start giving the idea attention – not least because groups like the Haida Salmon Restoration Corporation already are