Kate Mackenzie The sobering news about geoengineering

So, geoengineering has had a good year so far. After some optimistic exhortations from the Institution of Mechanical Engineers, the Copenhagen Consensus, and an encouraging mention from White House science advisor John Holdren, the idea of large scale interventions to offset the effects of climate change is having a good year.

However a year-long study by the Royal Society – the first comprehensive report by an influential science academy has not come up with such good news.

The diagram below displays affordability and effectiveness. And yes, on these measures alone, stratospheric aerosols – one of the more dramatic proposals – do pretty well:

However it doesn’t factor in safety; as this next chart shows, aerosals fare poorly on that measure, as does ocean fertilisation – the effects of changing the marine ecosystem are too risky. That leaves the methods clustered around the centre, such as CCS – which, despite being unproven at scale, also fares relatively well on the ‘timeliness’ spectrum, and biomass combined with CCS (labelled BECS in both diagrams):

Royal Society 'Geoengineering the climate' report

Source: Royal Society

There are a few optimistic notes in there – for example the report notes that techniques tackling methane gas, which is more harmful than carbon dioxide, but can leave the atmosphere more quickly – have not yet been explored. But the report’s chief author, John Shepherd, was unequivocal in his reservations about geoengineering as a solution:

“We are not advocating geo-engineering. It is not an alternative to emissions reductions.”

The bottom line is, it seems: geoengineering shouldn’t be seen as an easy way out, and we don’t know enough about it. But, reluctantly, it would be worthwhile finding out more. From the report:

It is clear that the available evidence is not yet sufficient for any well-informed decisions to be taken on the acceptability of any of the geoengineering techniques that have the potential to make a significant contribution to the moderation of anthropogenic climate change.

And from Dr Shepherd:

“Unless we can succeed in greatly reducing CO2 emissions, we are headed for a very uncomfortable and challenging future, and geo-engineering will be the only option left to limit further temperature increases.”

Another positive note is that the report suggests 10 years should be enough time to more comprehensively assess the potential of many geoengineering techniques. And this assessment can’t come soon enough: interest in geoengineering, despite the little that is known about it, is shooting up this year, as Google Trends shows:

Google Trends

Source: Google Trends

Related links:

Report criticises geoengineering techniques (FT, 02/09/09)
Geoengineering: You’re probably already doing it (FT Energy Source, 27/05/09)