…we were asking whether it was possible to create a zero-carbon world, a special issue seizing the opportunity of the climate summit in Cancún to present a more optimistic picture. Does any of this sound familiar, not least to those who read last month's issue on the lead-up to the climate summit in Paris?

Ever since we first tackled global warming in earnest (back in April 1990) we have faced the perennial challenge of how to return to the same topic again and again without readers switching off in either boredom or despair. In a sense, it is the same problem faced by the mainstream media – except that, while they are all too willing to escape into celebrity fluff or consumerist propaganda, there is no real escape for us from the reality that this is the Mother of All Crises and that we need to keep up the pressure on politicians unable to see past their next election.