22 March 2011, 09:51 BST
John Shepherd explores the morality and global implications of geoengineering solutions
Humans have always had to struggle with nature, both by adapting to it and attempting to master it. We wear clothes, and build houses. When the weather grows cold, we burn fuel for warmth. When darkness falls we light candles, or use electricity for light and entertainment. We build machines to move ourselves around, and cure many of the ailments that nature throws at us.
In so many ways, we enjoy the bounty of nature while insulating ourselves from its harshness.
Beyond this list of wonders, though, there remain some areas where nature still holds sway over us: none more so, perhaps, than weather and climate. We cannot control it; we can only adapt. Despite our best efforts over the centuries, we can't make or stop the rain, we can't make it warm or cool. We can only learn to live with the consequences.
Now, it appears, we might have the power to engineer the climate to suit our needs.
Past attempts at modifying the weather in our favour, from primitive rain dances to modern day cloud seeding, have met with a combination of failure, ridicule and suspicion. Fears of military applications of nascent technologies led to the Environmental Modification Treaty (ENMOD), enacted in 1978. This banned weather modification for hostile use, but allowed for further research for peaceful purposes.
We have, of course, already altered the Earth's climate â but only by accident, as an unexpected side effect of our efforts at advancement. Now that this accident is beginning to look potentially catastrophic, some scientists are considering how we might deliberately intervene to modify the weather on an unprecedented, planetary scale: by geoengineering the climate.
It is a simple enough idea. By scrubbing greenhouse gases directly from atmospheric air, or by reflecting away a small percentage of the sun's light and energy, it could be possible to reduce, or even reverse, the rate of global warming. It might conceivably be feasible to halt it altogether, and stabilise the climate in an optimum state.
Therein lie both the promise and the peril of geoengineering. On the one hand, it could buy us vital time to reduce emissions to a sustainable level. Despite global negotiations for over 20 years, we have not yet cut our overall carbon emissions at all, let alone on the scale required. So if geoengineering does turn out to be feasible, as well as easier, cheaper or more politically acceptable than reducing emissions, then it could rapidly become the path of least resistance.
But this could create a moral hazard: after all, why incur all the cost and complexity of cutting carbon if geoengineering makes it possible to carry on business as usual? There may also be unexpected â and potentially disastrous â side effects. Never before have we tried to modify our environment on such a scale. If we succeed in doing so, it may come to be considered humanity's greatest achievement â or its worst mistake.
Even researching its potential is fraught with difficulties. For example, large-scale field trials of solar reflection methods, which could elicit a measurable response in the climate system, would come perilously close to actual deployment of the technology. However, until we undertake such trials, we can never be sure what the results will be in the real world. Some people argue that we should therefore refrain from research on such techniques, as the risks may become too great. Others argue that the risks of unabated climate change outweigh them, and that we would be foolish not to explore the possible benefits.
Then there are a host of ethical questions to wrestle with. Who should decide what geoengineering activities go ahead, and where and when? Almost by definition, their impact cannot be restricted to international boundaries. It is not hard to imagine the tensions that may be caused by an extreme weather event occurring in one country shortly after another, perhaps rival, power has conducted a large-scale test. Even if we managed to minimise all unwanted side effects, we would still need to resolve who gets to control the 'global thermostat', and for whose benefit. Cold, wet countries and hot, dry ones are unlikely to agree on what the ideal global temperature or levels of rainfall should be.
These discussions take on added urgency as the business potential of some geoengineering techniques becomes apparent. If the cost of removing a tonne of CO2 from the atmosphere becomes cheaper than that of abating the activity producing it, then a viable business model emerges, quite literally, out of thin airâ¦
Whether and how these issues can be resolved in our far-from-perfect system of international relations will determine whether geoengineering is something that is handled with responsibility, cooperation and prudence, or with hubris and narrow
The UN Convention on Biological Diversity has already made the first tentative steps towards governance of geoengineering activities.
At its November 2010 Conference of the Parties, it advised governments to ban large-scale geoengineering activities that may affect biodiversity, while allowing for small-scale research to proceed.
Now the Royal Society is joining TWAS (the academy of sciences for the developing world) and the Environmental Defense Fund in convening the Solar Radiation Management Governance Initiative (SRMGI). Its aim: to foster international dialogue and cooperation on the issue, to ensure that any research that may be done is safe, transparent and responsible.
Of course the real decisions on geoengineering will eventually have to be taken by national governments. However, it is vital that such decisions are founded on sound science, with well thought out governance structures and broad public participation. It is not too soon for the scientific community to begin the dialogue with civil society that can help to achieve this.
WHAT'S IN A NAME?Geoengineering is "the deliberate large-scale intervention in the Earth's climate system, in order to moderate global warming".
Geoengineering the climate, Royal Society, 2009.
Being asked if you are in favour of geoengineering is like being asked if you are in favour of drugs. Which drugs? In what circumstances? Recreational or medical? Similarly, what kind of geoengineering? What are you trying to achieve with it? There is actually very little that one can say about geoengineering (or drugs) in general that is both true and useful.
The potentially serious problems that generalisations can cause were highlighted recently when the UN Convention on Biological Diversity [see above] debated a proposed moratorium on "all geoengineering activities". One assumes that the delegates didn't really want to ban planting trees or painting roofs white, but the language they supported would have done just that.
A problem for those who want to have a serious discussion is that 'geoengineering' often calls to mind the most outlandish interventions. For this reason many people have dismissed the whole concept as a 'bad thing'. But are there useful alternatives to the term?
Sensible discussion should, in the very least, start by dividing the techniques into their two main categories: those which aim to remove excess quantities of carbon dioxide from the atmosphere (so tackling one of the prime causes of global warming), and those which aim to reduce the amount of solar radiation reaching the Earth's surface (so reducing global surface temperatures without tackling the cause of their rise). The former are sometimes referred to as 'carbon-negative' strategies; the latter as 'global dimming'. The Royal Society favours the (arguably more precise) terms, carbon dioxide removal (CDR) and solar radiation management (SRM). While these have been quite widely adopted by the specialist academic community, there aren't many signs of them replacing 'geoengineering' in the public and the media.
A major conference looking at the governance of all geoengineering techniques, held in Asilomar, California, in March 2010, dispensed with the term altogether, using 'climate intervention' and 'climate remediation' to refer to SRM and CDR respectively. However, this met with the accusation that an unpopular idea was undergoing a PR rebranding. True or not, the new terms appear not to have become popular yet.
Controlling language may be almost as difficult as controlling the weather, and perhaps the best option is not to fight the 'G word', but to nudge it in a new direction, by referring to 'carbon geoengineering' and 'solar geoengineering'. These terms are still not perfect, but they're certainly more descriptive than 'geoengineering' on its own, and could help to prevent misunderstanding if adopted.
CDR v SRMGeoengineering methods can be split into two broad categories, which act on different parts of the climate system:
â¢ Carbon dioxide removal (CDR) techniques, to take out CO2 from the atmosphere, so reducing the greenhouse effect.
â¢ Solar radiation management (SRM) techniques, to reflect a small percentage of the sun's light back into space.
Carbon dioxide removal
Were time not a factor, CDR would be much preferable to SRM for addressing climate change. This is because it treats the cause of climate change (the accumulation of greenhouse gases in the atmosphere) rather than just counter-balancing the effects (by reducing the amount of incoming sunlight). In most cases, but not all, CDR techniques also have less potential for unpredictable side effects.
CDR techniques include:
â¢ land use management to enhance carbon sinks (eg planting and growing trees)
â¢ biomass for carbon sequestration (eg biochar)
â¢ enhanced natural weathering (using ground-up rocks to absorb CO2)
â¢ direct removal from the air ('scrubbing' CO2, possibly for use as fuel)
â¢ ocean fertilisation to encourage the growth of algae to absorb carbon.
Solar radiation management
SRM would reduce the amount of sunlight reaching the Earth by a small amount. It could reduce global warming much more quickly than CDR, and would likely be much cheaper to deploy.
However, SRM techniques don't treat the cause of climate change, would have a much higher risk of unexpected consequences, and would not address other effects of increased greenhouse gas concentrations, like ocean acidification. As such, they should only be considered as a potential temporary stopgap to avert a crisis, or to buy more time while emissions are brought under control.
SRM techniques include:
â¢ increasing surface reflectivity, by brightening man-made structures (eg whitening roofs), planting more reflective crops, or placing reflective materials in deserts
â¢ making marine clouds more reflective
â¢ distributing aerosols into the atmosphere to mimic the effects of volcanic eruptions
â¢ placing shields or deflectors in space to divert solar energy away from the Earth.
These methods could have a notable effect on the climate in less than a year, and some are projected to be extremely cheap relative to reducing carbon emissions. However, there remains considerable scientific uncertainty about the overall climatic impacts of solar geoengineering (eg on patterns of rainfall).
John Shepherd is Professorial Research Fellow in Earth System Science at the University of Southampton, UK. He chaired the Royal Society study on Geoengineering the Climate in 2009. Additional material by Michael Ashcroft and Andy Parker.
Source: Forum for the future