When European Union governments agreed in 1996 that avoiding 'dangerous climate change' meant keeping global average temperature rise during the 21st century to less than 2°Celsius, it was widely said that this could be achieved by allowing atmospheric concentrations of greenhouse gases to rise to about twice the pre-industrial level -- that is, about 550ppm CO2(e). (At present Angela Merkel and other European politicians remain adamant about the 2°C target, and it looks as if the European position will be buoyed by the Brazilian government, among others.)
But at least since a conference organised by the UK government in February 2005 (and Avoiding Dangerous Climate Change, an edited version of the conference papers published as a book early in 2006), it has been increasingly held as credible that stabilisation at 450ppm or less will be necessary to have a fair chance of avoiding a rise of more than 2°C.
Accepting this position for the sake of argument [as does a background paper I wrote earlier this year for a UN report that appears later this year], I'd like to highlight what I think could be a matter that is not as well or widely discussed as it should be: some forms of geo-engineering or geotherapy should not be dismissed at the start of serious discussion about how to manage climate change.
Consider a point made by Paul Baer and Michael Mastandrea in High Stakes (IPPR November 2006), and restated in Two Degrees, One Chance, a paper from 4 UK development NGOs published for this week's G8 conference. They note that the most stringent pathway for GHG reductions still carries a 9 - 26% [i.e., up to about 1 in 4] risk of exceeding 2°C. "This pathway requires emissions globally to peak in 2010 and then contract by 5% each year thereafter, reducing concentrations to below 400ppm by the end of the century" (page 7 of the latter document).
I have never met someone I would consider sane who believes that global emissions can be made to peak in 2010. So if Baer and Mastandrea's reasoning and the modelling on which it is based are correct, then (I think) this follows: to be reasonably confident of a greater than 3 in 4 chance of avoiding 'dangerous climate change' we need to find out what possibilites, if any, there may be to actively reduce GHG atmospheric *concentrations* (and not just emissions) within the next few (say, one to five) decades. Hence the likes of Richard Branson's CO2 prize.
Amongst the arguments against this case are:
1) it can *never* work;
2) the cure may be worse than the disease; and
3) it will encourage people to think they can continue to pollute now because someone else will bail them out later -- a version of 'moral hazard'.
I have not seen a convincing rationale for 1), but would be glad to read or hear one.
As for 2), well yes there will always be some truly terrible ideas out there; but it is not clear that one that has had some air play -- Paul Crutzen's thought experiment on injection of aerosols into the stratosphere -- will necessarily be worse than the full range of effects of 'dangerous climate change'. And put that to one side, there *may* be (I am not saying *are*) other ideas which could deliver actual benefits such as large scale but community-based and controlled creation of biochar (Johannes Lehmann of Cornell University says biochar in combination with biofuels could store up to 9.5 billion tonnes of carbon a year. He may or may not be right, and he is one of the first to call for more R&D. See: Which biofuels? 2)
And regarding 3), of course there are plenty of people looking for excuses to keep polluting and who may latch on to geo-engineering but I think this misses an important point about where we actually are. 'Moral hazard' is most often used in argument by people on the right of politics -- to argue, for example, that healthcare should not be free because this only leads to abuse of the system. That risk exists of course, but the reality can be rather different, as Malcolm Gladwell has shown. With regard to climate change we are already in the emergency room. The science seems to be making it pretty clear that we need to take all possible measures to reduce emissions, but even if we do there may still a high level of risk (i.e. up to 1 in 4) of dangerous climate change. It may therefore be prudent to look at the possibilities, if there are any, for accelerated reduction in atmospheric concentrations back down below 400 and even to pre-industrial levels within a few decades (something alluded to by Tom Goreau at least 15 years ago).
Whatever the truths of these matters, future argument will benefit from more thought and less emotion, moralising and opprobrium. On this point, though on little else, I partly agree with Josie Appleton who criticised Six Degrees for not talking 'the language of environmental management'. As I wrote in my own review Six Caveats about Six Degrees, '...The fifth caveat is that Six Degrees makes only a brief contribution on perhaps the biggest of all questions: what humanity needs to *do* to get its act together...'
Having got so many people excited about climate change maybe we need to work hard on making this issue a little more boring. But even agendas as ambitious as that outlined in Heat may be inadequate to the challenge.
(see also A 21st century greenhouse gas budget?)