Posted on September 1, 2009 at 10:41 pm,

The BBC reports that the Royal Society has been evaluating the possibilities of Geo-Engineering to reduce climate change.

Geo-engineering, if you haven’t come across the term before, means dealing with climate change in ways that don’t involve cutting carbon emissions. The report examines a whole range of technologies which are said to be able to counteract the increase in the number of greenhouse gases, all of which require further research to be feasible.

The report takes the rather sensible line that these options should not become a diversion from efforts to reduce carbon emissions. It also points out that the technologies all have serious risks and uncertainties. But it does outline which options look the most practical should we come to that point.

My own conclusion from reading the summary is that the use of geo-engineering techniques would indicate that the human race has failed to take seriously our duty to care for the planet we live on. However, if we fail to take appropriate action now, then these more risky and costly alternatives may prove a necessary evil.

Our response to this report should be to increase our efforts to reduce carbon emissions, in order to ensure that such methods do not become necessary.

The strategies they suggest are viable fall into two categories.

Carbon Removal Techniques

These are ways of taking the carbon out of the atmosphere, solving the problem at its root cause. It identified three with the most useful potential.

  • The report said that three are currently no cost-effective ways of capturing carbon directly from the air, although this would be the best possible option.
  • Enhanced weathering – using naturally occurring reactions of CO2 with rocks and minerals – may have wider environmental implications, but may prove a long-term option.
  • Land use and planting forests. The report said that this could play a small but significant role. However, there are issues regarding other priorities with regard to the use of land.

I don’t think that use of any of these methods, in conjunction with reducing emissions, would be disastrous. In particular, the problems regarding land use are probably the easiest to overcome. Archaeology and historical accounts tell us that the Amazon rainforest supported a fairly large population before Europeans arrived on the continent. Apparently large chunks of it were effectively an orchard. Creative use of land could enable us to combine human needs with the need to preserve forest areas.

Solar Radiation Management

These strategies involve trying to tinker with the radiation we receive from the sun. These methods are rather more drastic, but have the advantage that they could make an impact more quickly.

  • Stratospheric aerosols, which mimic the effects of major volcanic eruptions, appear to have much potential as a short-term solution. However, they would also have plenty of adverse effects. In particular, they would deplete the amount of atmospheric ozone.
  • Space-based methods (reflecting solar radiation away) would be slow to implement, expensive, and complex. Their main up-point is that they may provide a long-term effect.
  • Cloud albedo approaches – creating clouds, or increasing their ability to reflect solar energy away from the Earth – could have specific localised effects, but has big question marks over their feasibility, effectiveness, and environmental impact.

Techniques of little worth

The report also identified three approaches which have less potential.

  • Biochar – essentially creating a charcoal-like substance to lock carbon into the soil. The report was sceptical about its scope, effectiveness, and safety.
  • Ocean fertilisation – dumping large amounts of iron into the sea, in order to increase the number of plankton, thus enabling the ocean to absorb more carbon dioxide. The report concludes that it is unproven and has a very high potential for unintended negative side-effects.
  • Surface albedo approaches – basically making the Earth more reflective. These were found to be ineffective, expensive, and likely to have negative effects on local weather patterns.

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