Australasian Science Magazine

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By Christopher Doyle

As global action to reduce greenhouse gas emissions continues to stall, can engineering the climate provide a feasible solution to climate change?

The planet is overheating, and humanity faces an impending catastrophe unless scientists and engineers can find a radical solution that will save civilisation as we know it. Putting mirrors into space and shooting reflective particles from cannons out into the atmosphere are just some of the options that have been placed on the table.

While it sounds like the plot of a science fiction movie, this situation is not too far from reality. The climate is indeed warming as global efforts to reduce greenhouse gas emissions continue to stagnate. And as concern among the scientific community grows about the predicted effects of climate change, not only on humans but also on ecosystems across the planet, talk has turned to potential ways to engineer the global climate in order to avoid a climate catastrophe.

Climate engineering – or geoengineering as it is more commonly called – is a term used to describe the intentional, large-scale manipulation of the environment and planetary weather systems. Once a taboo topic among climate scientists, geoengineering is now gaining traction as a potential option for countering the effects of anthropogenic climate change.

Meetings to discuss geoengineering technologies have been held in Europe, North America, South America and Australia. The Intergovernmental Panel on Climate Change aims to provide an assessment of geoengineering technologies in its fifth assessment report due out later this year, while the United States and the United Kingdom have created commissions to investigate the feasibility and risks associated with geoengineering.

Of course, not everybody agrees that deliberately tinkering with the global weather system is a good idea, and geoengineering has gained some strong opposition from scientists and environmentalists who believe it is a band-aid solution at best. According to David Karoly, Professor of Climate Science at the University of Melbourne, geoengineering is “like treating the symptoms of a disease rather than treating the disease itself”. Karoly believes that we should be investing in renewable energy sources that would reduce the emissions of greenhouse gases into the atmosphere in the first place – the direct cause of global warming.

However, proponents of geoengineering argue that there has already been a failure to curb emissions to the levels required to prevent a drastic warming of the planet. They say that transitioning to an economy based on renewable energy sources is going to take time, a luxury that we may not have.

Dr Graeme Pearman, a private consultant and Adjunct Senior Research Fellow at Monash University, believes that research into geoengineering is needed in the face of an uncertain future. Like Karoly, Pearman advocates the need for increased research and investment in renewable energy sources, but he also believes we need a Plan B. “To me there is a risk – maybe low probability, but high impact if it occurred – that we have underestimated what we are in for. If that is the case, then I would rather be technically ready to do something about it than not. [That way] if that did occur, and let’s hope it doesn’t, we would be able to say: ‘Here are some technical options that we could take.’”

But can the technical options being discussed actually slow down the warming of the planet? The answer to this question lies not only in the scientific and technical issues associated with cooling the planet, but also in the ethical and political challenges posed by deliberate interference with the global climate.

Geoengineering technologies fall into two broad and very different categories (see box). The first category is referred to as carbon dioxide removal (CDR), and it includes systems that enhance the absorption of carbon dioxide from the atmosphere into natural carbon sinks – oceans, forests, rocks and soils. Examples of CDR include afforestation, enhanced weathering of rocks, liming of the oceans, large-scale pond production of algae, and fertilising oceans with iron to increase algal growth. Other CDR technologies involve capturing carbon dioxide from the atmosphere by chemical means, with the captured carbon being stored deep in the ocean or in geological structures.

The second category of geoengineering technologies is known as solar radiation management (SRM). Unlike CDR, SRM technologies make no attempt to reduce atmospheric carbon dioxide concentrations but rather are designed to reduce the amount of solar radiation reaching the Earth’s surface, thereby making the planet cooler than it otherwise would be. Examples of SRM include space-based mirrors that block a portion of incoming solar radiation, and increasing the surface reflectivity of the Earth by increasing cloud cover, whitening clouds, or injecting reflective sulfate particles into the stratosphere.

There are advantages and disadvantages to both CDR and SRM technologies, and they vary depending on the actual technology being examined. In general, though, CDR technologies tend to be favoured over SRM as they address the root cause of climate change by reducing atmospheric carbon dioxide concentrations. In addition, as they can generally be scaled up or down depending on requirements, they can be deployed on a regional level.

However, it is most likely that large-scale implementation would be required in order to have any significant impact on carbon dioxide concentrations and, therefore, the global temperature. This has raised concerns about the environmental impacts of implementing such large-scale activities, particularly when it will take decades to have any noticeable effect on the climate.

SRM technologies, on the other hand, require only a matter of weeks rather than decades to have an impact on global temperatures. Proponents of SRM argue that if human civilisation is confronted with a climate emergency, then SRM will be the only feasible way to cool the planet in a short enough time to avoid a catastrophe.

However, while SRM may cool the planet quickly, it may just as rapidly lead to adverse impacts on the global community. For example, Karoly warns that injecting aerosols into the stratosphere to reflect solar radiation, the most widely touted of the SRM technologies, would increase ozone depletion and alter rainfall patterns in the tropics. “I’m not quite sure why people are suggesting that slowing down climate change by killing more people with UV radiation and skin cancer and causing droughts in tropical countries is a good solution,” he says.

SRM technologies also provide no solution to the other symptom of increased atmospheric carbon dioxide concentrations – ocean acidification. It is estimated that the world’s oceans are absorbing one-quarter of anthropogenic carbon dioxide emissions, but increasing levels of carbon dioxide in the oceans are making the seawater more acidic. Continued ocean acidification is predicted to have far-reaching effects on marine ecosystems, including disrupting food chains, decimation of coral reefs, and increased vulnerability of fisheries.

It is generally agreed that the global climate following deployment of SRM would be vastly different than if atmospheric greenhouse gas concentrations were decreased, either through the use of CDR technologies or by cutting industrial emissions. According to Pearman: “The problem [with SRM] is that you actually install a different climate change because you won’t actually exactly offset the changes that occur at different regions of the planet. That means that anyone who does this has an ethical responsibility to all the other people who may or may not be disadvantaged.” This is some responsibility given that every person on the planet could quite justly claim to be a stakeholder in the global climate.

This raises the question as to who gets to set the global temperature. After all, not all nations, and certainly not all corporations, necessarily perceive climate change as a bad thing. For example, the retreat of Arctic sea-ice has opened up the possibility of oil and gas exploration in previously unreachable areas, and increased commercial shipping is now possible through the Northern Sea Route.

Clive Hamilton, Professor of Public Ethics at Charles Sturt University and author of the Earthmasters: Playing God with the Climate, believes it would be extremely difficult to reach a global consensus on geoengineering. He says: “It is likely that one or a small group of powerful countries will have the capacity and resolve to implement or deploy a geoengineering technology, and it is not difficult to foresee that poorer and less powerful countries will be sceptical about the nations that have their hand on the global thermostat.”

As there is currently no legal impediment to undertaking some of the geoengineering technologies being discussed, Hamilton argues that there is a need for an international body to govern research into geoengineering in order to minimise the possibility of an individual or a nation acting unilaterally. “I think there is a major role for Australia to play to bring together the international community to try to develop an effective legal structure for regulating research into geoengineering and deployment if it ever comes to that,” he says.

Pearman agrees, adding: “There needs to be some protocols with regard to what research can and can’t be done, and that shouldn’t be left up to individual scientists or institutions to make that sort of decision”.

According to Hamilton, a large part of the research to date has been driven by private companies, which creates another dilemma. “We’re talking about technology designed to save the world from catastrophe, so in my mind, turning that into a profit-driven activity in which patents for these technologies will be owned by private companies really stinks to the core. If we are going to have geoengineering research then it should be publically funded and the results should be publicly owned.” After all, what price do you put on a world-saving technology?

There is no doubt that the focus on geoengineering will continue to increase over the coming decades, both as the research into the various technologies ramp up and as the topic enters the public debate. But does the mere discussion of geoengineering actually reduce the likelihood of cutting emissions of greenhouse gases?

According to Hamilton, this is almost certain to happen. “Geoengineering looks like an easy way out, or certainly can be presented as an easy way out – a relatively cheap way of responding to climate change without antagonising the oil giants, the coal companies and consumers who are obsessed with petrol prices. I think there is every likelihood that politicians, corporations and opinion makers will seize on geoengineering as a get-out-of-jail-free card.”

This presents an interesting conundrum, as geoengineering is more likely to be successful if coupled with reductions in industrial greenhouse gas emissions. CDR technologies will lead to faster decreases in atmospheric carbon dioxide concentrations and therefore a slower rate of warming, while reductions in emissions are essential under SRM in order to minimise the impacts of ocean acidification.

Nearly every report on geoengineering to date has stated that reducing greenhouse gas emissions must be the primary goal of any climate change policy, yet this crucial step may be overlooked by the powers-that-be due to the mere promise of a technological fix. The situation will undoubtedly grow more complex as industry and lobby groups with a vested interest in continuing to emit greenhouse gases and in profiting from geoengineering technologies influence the debate.

There is no doubt that if it were successful in countering the effects of climate change, geoengineering could potentially lessen a great deal of human suffering and environmental harm. However, many of the geoengineering technologies proposed to date have yet to be realised or even tested, while others cannot even be tested without causing large-scale changes to global weather systems.

There is still a long way to go before a scientifically-sound and defensible technology is made available. Even so, the ultimate stumbling block could be the ethical, political and legal hurdles that geoengineering must clear before it can be implemented.