Let’s be clear that we are talking about a potentially awesome issue. On the one hand, emissions from human activities are interfering in two of the most fundamental driving forces of the natural planet: the heat balance of the atmosphere, with its basic patterns of climate, rainfall and ice cover; and the carbon cycle that is intrinsic to global ecosystems.
Of course there are big uncertainties: we don’t understand the consequences of what we are doing. That is hardly comforting; and the omens, including the accelerated break-up of Antarctic ice shelves, the extreme weather events of the 1990s and question marks over the stability of the Atlantic circulation patterns, can only reinforce concern.