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Climate intervention schemes could be undone by geopolitics

By Mike Hulme - posted Monday, 21 June 2010

As global warming intensifies, demands for human manipulation of the climate system are likely to grow. But carrying out geoengineering plans could prove daunting, as conflicts erupt over the unintended regional consequences of climate intervention and over who is entitled to deploy climate-altering technologies.

Last month, J. Craig Venter announced that his team had successfully developed the first self-replicating cell to be controlled entirely by synthetic DNA. Not artificial life exactly, but certainly something different: a synthetic cell in which humans had intervened deliberately with the express purpose of changing the genetic structure and characteristics of a natural organism.

Humans are lining up comparable purposeful interventions in the functioning of another physical system - not the microscopic system of a bacterium, but the macroscopic planetary system that fashions and delivers all our climates. The range of such potential climate intervention technologies - from altering how much of the sun’s energy strikes the Earth, to removing carbon dioxide from the atmosphere - continues to expand against a backdrop of anxiety that humanity may inadvertently be pushing global climate toward a dangerous state.


These two new ventures - manipulating the biological functions of cells and manipulating the physical functioning of the climate system - may be seen as simply the latest steps in the enduring human project of seeking control over the physical world. Hominid mastery of fire in the Paleolithic brought about radical changes in the possibilities for human life, and the manufacture of antibiotic drugs in the 20th century opened up a wide range of new medical treatments that have reduced suffering and extended human life. Designing self-replicating cells and re-tuning global climate may therefore appear as inevitable developments in our ingenuity and our ability to manipulate the world around us.

But compared to the questions raised by Venter’s biotechnologies, two categorically different sets of questions arise about climate manipulation: How do we judge the risks of unintended consequences? And who is entitled to initiate the large-scale deployment of a climate intervention technology - and under what circumstances?

Proponents are suggesting two broad categories of technologies to roll back global warming. The first, solar radiation management (SRM), calls for altering the solar radiation budget of the planet, using such technologies as mirrors in space, aerosols in the stratosphere, and cloud whitening over the oceans. And then there are technologies, grouped under the category of carbon dioxide removal (CDR), that propose to accelerate the removal of carbon dioxide from the atmosphere by fertilising the oceans with iron, extracting CO2 from the atmosphere, or sequestering CO2 by heating biomass in oxygen-free kilns and burying the charcoal underground.

Such interventions would bring about, if not exactly artificial climates, then certainly synthetic ones. The calls for significant investments in these technologies have grown in boldness and urgency over the last few years. Whether from government agencies or private investors such as Richard Branson or the company, Climos, resources are being directed into pursuing something akin to Venter’s vision of synthetically controlled cells, but the “cell” in question here is the planetary climate.

Both genres of climate intervention technologies raise serious ethical questions about the propriety of such manipulations, about their accordance with the collective will of people on Earth, and about the unforeseen side effects of such interventions. But the proposition of creating synthetic climates through solar radiation management (less so with carbon dioxide removal) introduces a range of additional concerns not shared with microscopic cellular manipulation. These concerns arise from the brute fact that there is only one climate system with which to experiment, and it is the one we live with. If it is planetary-scale manipulation of climate that is desired - and it is - then experimentation has to be conducted on a planetary scale to prove the effectiveness - or not - of the technology.

The first concern is the risk of unintended consequences. Given that it is not possible to conduct large-scale planetary experiments in solar radiation management before going “live” with the technology, risk assessments have to fall back on using virtual climates generated by computer models. The Earth system models currently used to explore the possible future effects of rising atmospheric concentrations of greenhouse gases are the same ones that have to be used to explore the simulated consequences of a variety of solar radiation interventions.


Using aerosols to offset the additional planetary heating caused by greenhouse gases is a relatively straightforward theoretical calculation; it is a case of simple planetary budgeting. Much harder is to know what this “re-balancing” of the global heat budget will do to atmospheric and ocean dynamics around the world. These are the dynamics that make weather happen at particular times and in particular places and which - through various combinations of rain, wind, temperature, and humidity - shape ecological processes and human social practices. The dangers and opportunities associated with climate occur through these local weather phenomena, not through an abstract index of global temperature.

If the goal of climate engineering is simply to reset the global temperature dial at its 19th or late-20th century register, that might be possible to do. But in the process of doing so, significant perturbations to regional climate conditions, and inter-annual variability around those conditions, are likely to be introduced. Even if changes in the frequency and intensity of storms and precipitation were to be a zero-sum game globally, the distributional effects of such changes will create winners and losers. Such phenomena as El Niño, the Asian monsoon, and the Arctic Oscillation will not remain unaffected. And given the far-from-adequate ability of Earth system models to simulate the regional-scale dynamics of the hydrological system, no one should be confident that the full risks of solar radiation management interventions will be revealed and quantified.

Which brings us to the second question that sets apart the project to fashion a synthetic climate from the project to create synthetic self-replicating cells: Under what future scenario could one imagine full-scale deployment of solar radiation management taking place? Many commentators have drawn attention to the multi-layered issues of financing, ethics, governance, geopolitics, and public opinion that surround most of these solar radiation intervention technologies. These were very much to the fore at the recent Asilomar International Conference on Climate Intervention Technologies in California earlier this year.

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First published in Yale Environment 360 on June 7, 2010.

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About the Author

Mike Hulme is professor of climate change in the School of Environmental Sciences at the University of East Anglia, Norwich, UK, and was founding director of the UK-based Tyndall Centre for Climate Change Research. His most recent book is called Why We Disagree About Climate Change.

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