Bus CO2 Emissions Puzzle

One useful piece of bus information comes in the annual report by TfL’s Mike Weston to the Hybrid User Forum – this year’s is rather disfigured by too much NB4L rubbish, but there’s always an interesting graph of predicted bus emissions based on the introduction of various new initiatives.  Close examination of this year’s graph against the last two years, helpfully labelled with the introduction dates for the NB4L, hides a dirty little secret:

Compare the CO2 line on the 2011 and 2012 graphs – in 2011 the expectation by 2017/18 was a reduction to just under 500k tonnes of CO2 per year – this year the expectation by 2017/18 and four years of NB4Ls is a reduction to around 540k tonnes – about 50k tonnes more than was expected last year.  I don’t think Boris is planning to increase the bus network, so this is presumably down to the reduced number of hybrids being bought plus the rumoured life extension of older, more polluting buses that would normally be pensioned off to the shires by now.  It’s typical of Boris’s attitude to the bus system that he fails to grasp the nature of the system in the round.  Another FoI beckons…