The broad theory of man-made global warming is acceptable in the purely qualitative sense. If humans continue to fill the atmosphere with carbon dioxide, there can be little doubt that the average temperature of the world will increase above what it would have been otherwise.
The argument about the science is, and always has been, whether the increase would be big enough to be noticed among all the other natural variations of climate. The economic and social argument is whether the increase, even if it were noticeable, would change the overall welfare of mankind for the worse.
Attempts to resolve the arguments are plagued with problems, a lot of which are inherently insoluble. There are many aspects of the behaviour of the natural climate system and of human society that are unpredictable in principle, let alone in practice. But perhaps the biggest of the underlying problems, and it is common to both arguments since it inevitably exists when there is large unpredictability and uncertainty, is the presence of strong forces encouraging public overstatement and a belief in worst-case scenarios.
From the social and economic side of things, one might take much more notice of the global warming scare campaign if it were not so obvious that many of its most vociferous supporters have other agendas. There are those, for instance, who are concerned with preservation of the world’s resources of coal and oil for the benefit of future generations. There are those who, like the former president of France, Jacques Chirac, speaking at a conference on the Kyoto protocol in 2000, look with favour on the possibility of an international decarbonisation regime because it would be a first step to global governance (the president’s actual words were “For the first time, humanity is instituting a genuine instrument of global governance”.) There are those who, like the socialists of the 20th century, see international action as a means to force a redistribution of wealth both within and between the individual nations. There are those who regard the whole business mainly as a path to the sort of influence which, until now, has been wielded only by the major religions. More generally, there are those who, like the politically correct everywhere, are driven by a need for public expression of their own virtue.
Of course there is nothing wrong, or at least not much that is wrong, with the ideals behind any of the above agendas except perhaps the last couple on the list. But the battles over them should be fought in the open and on their own merits rather than on the basis of a global warming crusade whose legitimacy is founded on still-doubtful science and on massive slabs of politically correct propaganda.
It is generally assumed that climate scientists themselves are more or less united on the matter and are not pushing a global warming barrow because of their interest in some other agenda. Certainly this is the story the activists would have us believe.