Along with many other the global leaders, I too am burying my head in the sand.
I do so only because of this: as far as I understand it less than 4% of the greenhouse gases which account for so-called global warming are produced by human activity. The remainder stems from volcanic activity, reactions that take place in the sea, animals farting and so forth. Therefore, by my naive reckoning if mankind ceased producing all greenhouse gases immediately (neither practical nor desirable) this would lead to only a 4% reduction in emissions.
Add to this the fact that the UK produces less than 1% of the 4% and any measures taken by the UK (and the remainder of the world outside Europe is not so gullible) would be negligible.
If global warming is evident it is most unlikely to be due to human activity, and even less likely that mankind can do anything about it. Nonetheless, for many other reasons a considerable reduction in the human population is an extremely worthwhile aim, and one which none of the major powers apart from China seems willing to embrace.