Climate Engineering

A critical review of proposals, their scientific and political context, and possible impacts.

compiled for Scientists For Global Responsibility, November 1996

Ben Matthews

School of Environmental Sciences, UEA, Norwich NR47TJ
Fax 01603 507719, Tel (wk) 01603 593733,


This review of climate engineering proposals aims to provide a comprehensive resource of up to date information and ideas for people concerned about the development of large-scale technical fixes to counter the problem of global warming. The proposals fall into three main categories: increasing the reflection of solar radiation back to space, enhancing natural sinks of carbon dioxide, and direct disposal of carbon dioxide captured at source. In addition, proposals involving weather modification, ozone chemistry and terraforming Mars are mentioned briefly. Direct disposal of carbon dioxide is included because it involves exploitation of "global commons" such as the deep ocean, and because it is often compared with schemes to increase natural sinks. Some of these proposals are realistic and thus a real cause for concern, whilst the reader may find amusement in reading some of the crazier schemes! All of these technical fixes are intended to tackle the symptom of the problem of fossil fuel consumption. The development of technology to encourage energy efficiency or renewable energy, on the other hand, which is intended to reduce that consumption, is much less controversial, and is not considered here.

Some academic research projects which may lead to climate engineering, such as fertilisation of the Southern Ocean with added Iron, have recently received much media attention. However, the media seems to be less aware of the much larger community of researchers who are employed by the fossil fuel and power industries to investigate similar proposals for enhancing CO2 sinks. This review aims to clarify not only how each proposal might work or fail, but also who is promoting each idea. Sponsorship by the fossil fuel industry is closely linked to the bluffing game of international greenhouse politics, where excuses for doing nothing are always welcome. Hidden political values are concealed in cost-benefit analyses, in which a trade off can be made between climate engineering or climate warming damages, implying that consumption is already non-negotiable. The "just in case" argument for backing climate engineering research may become a self-fulfilling prophesy in this political context, but in the real world the choice might then be between two potential catastrophes, for positive feedback processes make the climate system inherently surprising. I conclude by asking whether such research should continue, and how we might check its momentum in the future.

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climate engineering proposals
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Addresses and web pages

Part 1. Introduction

Many of us like to think that our job plays some small role in the massive task of "saving the world". Myself, I was convinced long ago that global warming was the greatest potential threat to all life on earth, because we were entering unknown territory in a chaotic system dominated by little-known feedback processes. If positive feedbacks predominate in the "runaway greenhouse", this could spell the end of life on earth. On the other hand, I knew that for 4 billion years the Earth had remained comfortable for life, and this was largely due to negative feedback processes involving life itself. In particular, the beautiful little algae in the sea controlled the pump of CO2 from the atmosphere to the ocean, and thus kept the world cool. And so I ended up working here in the laboratory, measuring CO2 fluxes in and out of a tankful of such algae.

But in this university there are many others also motivated to "save the world", who find themselves instead studying development, social sciences or economics. And in a gathering of such people, they often grumble about how the "the World Bank (or similar organisations) rule the world". On such occasions, I sometimes like to jut in and point out that really, if anything, it is the algae in the sea that rule the world. For, in the long term at least, it is they that have controlled the chemistry of the ocean, and thus of the atmosphere, and thus the global climate, and despite our pollution they continue to do this, so far little perturbed..

However, I begin to wonder, whether maybe the others were right after all. For I can envisage, in the not too distant future, that economists could be telling us how we should control the algae in the sea, to control the climate as we want it, to find the most economically "efficient" response to global warming. They already produce global cost benefit analyses to tell us how much CO2 we should put in the sky, to best suit humans with money and power. But if they are given the link to the algae, it may be my own colleagues here who took the initiative to make it possible. New experiments on the "Iron Fertilisation hypothesis" last summer proved particularly successful. The scientists' motivation is not to control the world's climate, but curiosity to find out what does control the growth of the algae, necessary to understand ice ages and predict future climate change. But the question is, once you have the key to such "climate engineering", is it not likely to be developed, and directed according to the interests of money and power? History shows us, how the exciting science of one decade, turns into the more dubious technology of the next. Nuclear physics and molecular genetics are examples. Is it possible that the science of climate feedbacks, biogeochemical cyles, or "geophysiology" could be heading the same way?

My colleagues would probably tell me, that my World Bank scenario is alarmist and unhelpful, that's not what the scientists are intending. Some say that our task is only to solve the scientific challenge, and it is always better to possess the key to the mystery. Yet not surprisingly, there was a lot of controversy here after the recent publication of the results of the Iron experiment (more detail later), particularly fuelled by reluctance on the part of certain prominent researchers to reject the idea that their research might lead eventually to a partial technical fix to global warming. A hostile editorial in New Scientist (vol 152 no 2051) led to mudslinging in the media, for instance Jonathon Porrit's newspaper article "Beware the Quick Fixes of Nutty Professors" in response to another article welcoming this wonderful cure which might give us the freedom to drive more cars. It seems people either hate the iron fertilisation "quick fix" or love it, in rough proportion to their love of consumption and faith in technological "progress". The controversy encapsulated deep divisions.

Following from that, I decided to see whether there were other realistic "climate engineering" proposals in the scientific literature. I found about a dozen different ideas. These are considered in detail in section 2 of this paper. Of course, we should expect that in any field, there will always be some crazy proposals, many of which will never receive enough resources to be tested. But then I noticed that most of the papers came not from academics in institutions which pursue the basic science of global change, but instead from engineers, chemists, and biotechnologists who seemed to be sponsored by the fossil fuel or power industries. Sponsorship of climate engineering research is considered in section 3. It seems that these schemes are not just being suggested, but are already being pushed, as a cheaper alternative than reducing CO2 emissions. This made me much more concerned.

There are three reasons to be worried about this turn of events, and these are considered in section 4. First, the push to find such a technical fix, will distort the science of global change. Second, if there is a serious prospect of a technical fix, this will weaken people's resolve to take the responsible course of drastically reducing fossil fuel consumption. And third, most worrying but most distant in the future, there is prospect of these proposals becoming reality. For the global climate is a highly non-linear system determined by complex feedback processes , and we still have a poor understanding of how it works. Any attempt to deliberately tinker with this system, could backfire very badly. Most new experiments do not work the first time as expected. There are always unwanted side effects. But if we tinker with the whole world, we only get one chance.

So, I wondered, perhaps the time is ripe for concerned people to get together, to check the enthusiasm of the climate engineers, and provide a forum for consideration of the ethical issues and side effects? Possible approaches are considered in Section 5. This might be a new topic for organisations such as "Scientists for Global Responsibility", or for the more radical young scientists under the banner "new luddites", who have recently devised peaceful but innovative ways to question the "Optimism" of the scientific establishment, so far focussing on cars, genetic engineering, and specific events in science festivals. But it might seem strange for such "green" activists, to start questioning whether we should curtail some climate change research. And perhaps the proposals still seem so far fetched, that we would only make ourselves look silly, by taking them too seriously at the moment? I will postpone further judgement, and continue by outlining some of the proposals in more detail.

Note that US academics have coined the term "geoengineering" to describe this topic. However, both to me and to citation indices, this still tends to conjure up hard hats and oil rigs, belonging to more traditional applied geology. So for the moment, I will stick with "climate engineering". "Terraforming" is another term, but refers to other planets.

Click here to continue to Part Two : Climate Engineering proposals

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