Last week, the Royal Society held a public lecture entitled ‘Geoengineering the climate: A brave new world?’, following their September 2009 publication ‘Geoengineering the climate: Science, governance and uncertainty’. The lecture panelists, like the authors of last year’s publication, were from a wide range of disciplines, reflecting the diversity of issues which arise from geoengineering proposals.
Geoengineering solutions for combating global warming fall into two broad categories. The first, Carbon Dioxide Removal (CDR), addresses the principal cause of climate change by removing CO2 from the atmosphere, and so reducing the greenhouse effect. The second, Solar Radiation Management (SRM), involves countering the warming effects of high atmospheric CO2 by reflecting some of the radiation from the sun.
Examples of suggested CDR techniques include biochar; aforestation; ocean fertilisation; and enhancement of weathering. SRM methods include increasing the albedo of the earth, such as by painting building roofs white; increasing the reflection of radiation from the stratosphere by releasing aerosols; and space-based methods which reduce the amount of radiation reaching the earth, such as by launching reflectors into space.
The immediate benefit of CDR over SRM is that it removes CO2 and so would counter ocean acidification (and other CO2-related problems), whereas SRM only prevents warming. However, some methods for SRM could be deployed very rapidly, most CDR methods would take years or decades to become effective.
The only panelist who opposed any further research into geoengineering was Greenpeace senior scientist Dr. David Santillo. The opinion of Greenpeace, and of many other opponents, is that focussing on geoengineering solutions to the climate problem diverts attention (and funds) from what is sometimes termed ‘Plan A’: the reduction of CO2 emissions. The possibility of a ‘Plan B’ may be regarded by governments, industry and the public as an excuse to continue burning all remaining fossil fuel reserves. An uncertain cure in the place of a more reliable prevention.
However, it can not be assumed that all serious advocates of climate geoengineering see it as an alternative to emissions reduction, but rather as a necessary additional measure. This is the logical conclusion from the increasingly popular view that present levels of atmospheric CO2 are already so high that certain tipping points in the earth climate system have been reached (most recently). This position asserts that even if emissions fall to zero tomorrow, ‘catastrophic climate change’ is still probable.
The problems with geoengineering are wide-ranging and hard to predict, but stem from three main areas:
Firstly, designing successful methods to reduce either atmospheric CO2 levels, or solar radiation absorption require an excellent understanding of the earth system. At the Royal Society, Professor Corinne Le Quéré, from the University of East Anglia, reminded us that current models are still not accurately reproducing observation in a number of fields, Arctic ice melt, for example.
Secondly, implementation of the technology itself could prove prohibitively expensive. This is certainly the case with space-based SRM methods. As well as monetary costs, implementation of some technologies may be expensive in terms of space and resources. Aforestation, for instance, risks competing for fertile land with agriculture.
Thirdly, and perhaps most critically, major geoengineering projects would require international cooperation. Although some CDR techniques, such as biochar and land use changes, could be applied in specific areas, without need for consent from others, they would actually need to be implemented across large areas of the world to be effective. Certain SRM techniques, however, could be carried out by one country (perhaps by releasing aerosols into the stratosphere), and would be effective over the entire globe. This category of technique could be damaging to the climates of certain parts of the world, for example by reducing precipitation. Added to this is the fact that once a particular SRM is started, it will have to continue indefinitely. If suddenly terminated, rapid warming would commence, with disastrous consequences. After the recent failure of world leaders to agree upon emission reductions at Copenhagen, how can we rely upon them to reach an agreement over the much more complex issue of geoengineering?
Plan A may have already failed, plan B is not a silver bullet solution, which leads me to consider plan C: Adaptation. Millions, perhaps billions of people are at risk of being displaced by sea level rise, drought, famine and other effects of climate change. Humankind has adapted to changes in climate before, by migrating, by changes in behaviour, and by inventing new technologies. With a population of nearly seven billion, the task is certainly tougher this time. But perhaps it’s the most feasible option left to us.