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Geoengineering: do we intervene?

Tan Copsey
2 September 2009

As part of a series for chinadialogue that examines the environmental and political arguments around geoengineering, Tan Copsey spoke to Ken Caldeira, senior scientist at the Department of Global Ecology at the Carnegie Institution and a leading expert in "climate emergency response research". Caldeira is a contributor to the study published today by the Royal Society, Geoengineering the Climate: Science, Governance and Uncertainty, which asks whether planetary-scale geoengineering schemes could play a role in preventing the worst effects of climate change. Ken Caldeira is senior scientist at the Department of Global Ecology at the Carnegie Institution. Tan Copsey is development manager at chinadialogue.

Tan Copsey (TC): What geoengineering ideas do you think are being considered seriously by scientists?


Ken Caldeira (KC): I think it is useful to approach this question by asking what problems are we trying to solve. If we are trying to solve the problem of increasing climate risk and climate damage, then we need to consider transforming our energy system first. If we are concerned with catastrophic climate change, then that pushes us towards other techniques.

If we look at the IPCC [Intergovernmental Panel on Climate Change] predictions for global temperature over the century, in every scenario the world continues to warm. So the question is: if rainfall patterns shift such that we are no longer able to grow food properly for the world, or Greenland starts sliding into the sea, raising sea levels rapidly, or if methane starts catastrophically re-gassing from the Siberian frozen grounds, what would we do? This leads us to think about options that could be deployed very rapidly to cool the earth.

I think the leading candidate is to emulate what major volcanoes do, which is to put huge amounts of small particles into the stratosphere, where they can deflect sunlight back into space. We know this works, because after Mount Pinatubo erupted in 1991, the earth cooled about half a degree Celsius. It would have probably cooled three, four, or maybe five degrees had that amount of material been maintained in the stratosphere. While these are very risky types of things to do, I think that in a climate emergency situation we might have to deal with those risks.

There are other options that make some sense: one of them is the idea of whitening clouds by spraying sea water through the air. This forms tiny little salt particles that increase the whiteness of marine clouds [reflecting light back into space].

I think these are really the two options that have the most plausibility. Most other options are either too difficult or expensive - like the idea of putting satellites into space between the earth and the sun, which would be a huge and difficult engineering undertaking.

TC: Do you think that someone will need to deploy forms of geoengineering in our lifetime?

KC: I am uncertain about how bad climate change is going to be for humans. I think it is pretty clear that if you are a polar bear or a coral reef, your days are numbered unless we radically change our emission patterns very soon.

Climate change is clearly an issue for some ecosystems and it is probably an existential issue for some people who are already at the margins, where climate change could push them over the edge. But what climate change will mean for middle-class people, both in the developing and the developed world, I think is highly uncertain. There are some people, like Jim Lovelock, who think society is like a house of cards - climate change will shake the bottom of it and the whole thing might tumble down. With the recent economic crisis, we see some mortgage defaults in the United States leading to a worldwide economic downturn, so it may be that small disruptions will be amplified to have dramatic social consequences. On the other hand, society might be resilient, and humans might be adaptable, like rats and cockroaches.

Although I don't know how bad climate change is going to be for humans, I do know that there is at least the possibility of devastating consequences - so it just seems to me it makes sense that we have an insurance policy. We should be thinking about these outcomes, what might happen - and if they do happen, what might we do about them.

TC: Do you think there is a risk in talking about geoengineering as a solution - or part of a solution - to climate change, because it reduces the pressure on governments to act to reduce greenhouse-gas emissions?


KC: In this area of climate engineering, or climate intervention, there are at least two political threads. There are people who say if we reduce the risks associated with climate change, then we reduce the incentive to do something about emissions. And there are people who advocate these options in the hope that it will deflate pressure to reduce emissions. But there are other people, such as myself, who think that we need to take the threat of a climate crisis seriously. If you take that threat seriously, then you will think that we need to do what we can to reduce that risk by reducing emissions. But that's not going to reduce the risk to zero.

TC: Climate change is a global problem and its effects will be unevenly distributed across the world. Could action by a single nation ever be countenanced?

KC: I think this is a difficult question. It's easy to say that nobody should ever deploy one of these systems without getting global consensus - and in measured times that is what we would do. But let's say we had a situation where climate change was causing massive crop failure in China: what if Chinese scientists figured that if they intervened in the climate system by putting particles in the stratosphere, and this would likely restore the rains to China and allow China to feed its people once again? If the Chinese leaders thought that they would be saving many millions of lives by putting particles in the stratosphere, it's hard to imagine that a Chinese leader would say: "No, I'm going to let my people starve because I can't achieve international consensus." I think in the case of an emergency, where a political leader thinks it could potentially save many millions of lives, it's hard to see how that leader could allow their people to starve or die. I could envision a situation where political leaders might deploy these systems in the absence of a worldwide consensus.

That said, I think that it's important for us to get our governments to start discussing these issues and develop governance and regulation over these technologies to try to make sure that as much as possible there are international controls and consensus over how these tools are used. But I think when push comes to shove and a political leader has their back against the wall, they may feel compelled to deploy these things unilaterally.

TC: But surely ending a drought in one country - in China, for instance - by putting particles in the stratosphere might increase the adaptation burden in another country, such as India.

KC: Yes. In fact after the Mount Pinatubo eruption in 1991, the Ganges River had its lowest flow rates on record - and so we could very easily imagine that putting a bunch of aerosols into the atmosphere might affect the rains in the Ganges River basin. I think it's possible that if one country or region is in crisis, and one of these systems is deployed, then another region could very well be damaged. We don't know enough yet to be able to predict "who and when and how", but this kind of scenario seems likely. The idea that everybody is going to uniformly benefit from the application of these approaches is not at all clear.

This gets back to the governance issue: would whoever did this be liable for compensating people who were affected? There is a parallel to storm modification research in the United States in the 1960s: scientists were looking at steering hurricanes away from major cities. They eventually stopped the research for fear of liability issues - if you directed a hurricane away from a major city and hit some rural area instead, then even though you might have reduced damage overall, the people you did hit with the hurricane would sue you for damages, especially in the US, where we are very litigious. So I think these kinds of issues could occur on a larger scale.

TC: It sounds like this would make it even more difficult for anyone to reach a global decision on geoengineering. How would you come to an agreement? Is it possible?

KC: I think that these things will not be used except in times of extreme emergency. The idea that you would use these options instead of emissions reduction does not make sense given how great all these political, legal and risk factors are. We just wouldn't be able to deploy these systems in the normal course of policy or get international agreements that it's a good thing to do. But I think if Jim Lovelock's vision of climate change turns out to be right, then I think people might be more eager for something that could cool things off rapidly.

TC: Do you see geoengineering as an expanding discipline? Is there funding to pursue this kind of research?

KC: There are no programmes yet in any country to fund this research. I think we may need to re-conceptualise what the field of research is, away from focusing on specific tools and more onto climate emergency response research - and to say that if the worst did happen, what would we do? We shouldn't get into a situation where we only have a bunch of people developing technologies just for the sake of it.

Geoengineering the Climate: Science, Governance and Uncertainty, a policy report from the Royal Society, is published today. 

The article originally appeared in chinadialogue.

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