Climate change committee should take its own advice

Two years could make a big difference in stopping world temperature from rising above 2C, writes Duncan Clark

A couple of weeks ago I posted my first thoughts on the much-anticipated report from the Committee on Climate Change. My point was the clash between the report's stated aim of limiting this century's temperature rise to 2C. But what the reports recommends to achieve this – a peak in global emissions within 10 years followed by a 3% cut per year – has nearly a 70% likelihood of exceeding the 2C target.
Why, I wondered, didn't Adair Turner tell us what we'd need to do to avoid crossing the dangerous 2C threshold? Why didn't they include a more ambitious emissions scenario?
Looking at the report's technical appendices the authors have examined just such a scenario – with global emissions peaking in 2014, followed by an annual 3% cut. This, the figures show, would probably stop us overshooting a 2C rise this century.
Well, almost: the most likely outcome in this situation would be a 2.01C temperature rise above pre-industrial levels by 2099, compared with more than 2.2C if the recommendations were acted upon.
Which raises an obvious question: why on Earth was this scenario not given any real space in the main report, rather than just a passing mention about supporting research? And why, given that the committee had found a scenario that met their original criteria, did they not recommend it as Plan A?
Apologies if all this sounds overly geeky, but when it comes to possible planetary meltdown, I figure it's worth worrying about the small print. With that in mind, I asked the Committee on Climate Change what had happened.
The reply said that the committee hadn't made a big deal of the "missing" scenario as it allowed the same emissions in 2050 as the others. The reply also went into detail about computer modelling and cross-checking figures. It partly went with a 2016 peak, for example, because it allowed them to compare results with those from other bodies.
That's almost a satisfying answer, but not quite. Ultimately, if they worked out that a global peak two years earlier would take the most likely temperature change from 2.2C down to 2C, then we should be told that as loudly as possible.
And why had the committee opted for a peak "within 10 years", rather than by their already insufficient 2016? This, it turns out, was just "loose drafting" – the intention, apparently, was to suggest an emissions peak in 2016 after all.
All told, then, the committee's official message is that we need a global emissions peak by 2016. What the committee's numbers tell us is that we need a peak by 2014. Global leaders please take note.