The first instalment of the Intergovernmental Panel on Climate Change’s fifth report, published last autumn, stated that our environment is incontestably heating up and it is beyond reasonable doubt that human activities are the cause. The second, published earlier this week, concluded that global warming is already taking worldwide effect and threatens everything from crop yields to social cohesion. The tenor of the third, therefore, which is due for publication later this month, can hardly be a mystery. Even so, the first hints from a draft of the report are a stark vision of the scale of the challenge ahead.
If warming is to remain below the 2C threshold above which change becomes catastrophic, wealthy nations, including the sceptical US, will need to halve their carbon emissions by 2030. Fast-growing economies including India and China will also have to make significant reductions. Across the globe, cuts will need to go far beyond any existing targets, commitment to which is already far from guaranteed.
All of this only adds to concern at the glacially slow progress made so far. In Britain, worries over energy security and economic sustainability are putting pressure on green goals; indeed, the Treasury is reviewing the fourth phase of the so-called “carbon budget”, which runs from 2023 to 2027, with a view to slowing the pace of change. But even if the UK were to meet all its self-imposed obligations, that alone will have little impact beyond the setting of a fine example. Until there is a comprehensive global agreement, including a resolution of the thorny question of how to share the high costs of climate-change mitigation between developed countries (which polluted heavily in the past) and developing countries (which are doing so in the present), the prospects of meaningful advances are frighteningly slim.
At the last of the serial UN Conventions on Climate Change, in Warsaw in December, efforts towards a global deal made no material progress. But the crucial meeting, at which any new treaty on global warming would need to be signed, is not until next year’s event, in Paris. It can only be hoped that the IPCC’s blunt appraisal will focus minds. It should.