As often happens with the newly converted, Boris is now piously preaching to the rest of us on all matters green, for example in his latest Telegraph column on his way to the sideshows at the Copenhagen Summit. Not that he necessarily practises what he preaches. For a start, it would have been better if he had made the effort to get to Copenhagen by train via Brussels rather than on a short-haul flight.

Nor was it clear what he was doing there. Telling the world how London shows the way with retrofitting public buildings and promoting electric cars is all very well, but Boris can take little credit for the former policy, which was launched under the previous Mayor. As for electric cars, it is not at all clear that the Mayor is in a position to lead on this, given that the vast majority of charge points will have to be on suburban roads controlled by local authorities and not on the TfL red routes where we rightly have little off-street parking. And Boris fails to explain what the source of supply for the electricity will be. Is it to be from renewable energy sources or from the sources we are already using? If the latter, then even if electic cars would reduce noise and air pollution they would contribute little to reducing our carbon emissions.

And whilst Boris is preaching to the world about London’s achievements, we should not lose sight of the fact that, according to the Economist Intelligence Unit’s recently published European Green City Index, we are only a middle ranking city when it comes to greenery – in 11th place, just behind Paris. That’s the reality: in the European cities league table we occupy an equivalent position to Fulham or Sunderland in the Premier League, not Chelsea or Man United. Quite honestly only the host city Copenhagen, which comes out top of the Green City Index, is entitled to go preaching to the rest of the world on what cities can do to reduce their residents’ combined carbon footprint.

While he has a look at the tables in the Green City Index and London’s position in them, Boris should also take time out to reconsider his neo-Malthusian views on population growth as a cause of potential environmental catastrophe. (“We are replicating too fast,”, he tells his Telegraph readers, “hurtling towards nine billion souls on the planet like bacteria multiplying on a Petri dish.”) While the Evening Standard has highlighted how this does not fit very well with Boris himself having four kids (which of course is a personal choice), a more fundamental criticism is that the perspective of disaster caused by rising population has been discounted on numerous occasions before in history.

As I wrote about advocates of neo-Malthusianism in an earlier post:

“What they do not want to admit is that the fertility rate of half the world is now 2.1 or less, the magic number consistent with stable population, and that it’s expected to fall below this level between 2020 and 2050. (See the recent article in the Economist.) That’s not surprising as poor countries are going through the same demographic transitions that rich ones went through, but at an earlier stage in their development and much more quickly.

“As for environmental damage, the poorest people in the world like the Bangladeshis are producing at most 0.3 tonnes of CO2 emissions per capita annually, whereas a US citizen produces 20 tonnes. So, while it’s clear that if the poor countries recreate the same consumption patterns as the US we will certainly have some problems to deal with in the future, at present that is a distant prospect. It is the environmental damage caused by the developed countries that is the immediate challenge.”

Boris’s time in Copenhagen would have been better occupied advocating that cities should be party to any agreement, given that 75 per cent of the CO2 emissions originate from cities and the human race has reach a point now that 50 per cent of it now lives in these huge urban centres. Particularly now that nation states have proved unable to agree amongst themselves on the way forward after the Kyoto agreement, Boris should be calling for cities to step into the breach. Now that would be some leadership!