The media love a good argument, and what better than to pitch polemicists against each other from opposite ends of the spectrum? Thus we are given Björn Lomborg v Oliver Tickell in a so-called "climate debate" (Tickell's apocalyptic view obscures the solutions; Lomborg's stats won't mean much underwater, August 21). Regrettably, we learned from this only that sensible solutions are unlikely to flow from entrenched and extreme positions. Most scientists are amazed and alarmed that the issue of climate change should be treated as an article of faith - something either to be believed or disbelieved - rather than a problem surrounded by a lot of uncertainty. What we got from these two was very misleading.
Lomborg claimed: "A lead economist of the IPCC [Intergovernmental Panel on Climate Change] did a survey of all the problems and all the benefits accruing from a temperature rise over this century of about approximately 4C. The bottom line is that benefits right now outweigh the costs." There have been a few studies of the current effects of climate change (for example, on ice shelf and glacier retreat, and on plants and animals) and the IPCC has concluded these are happening faster than had been expected. But despite what Lomborg says there has been no useful assessment of whether these are beneficial or not, because aggregation of effects involves meaningless trade-offs such as comparing the destruction of Inuit communities with the benefits of ice-freed shipping lanes.
Lomborg believes that 4C of global warming "will not be a challenge to our civilisation" and derides Tickell, whom he quotes as stating that warming of this amount would bring "the beginning of the extinction of the human race". Both of these are heroic conclusions, since there has been no study of the limits to our adaptive capacity. The climate change issue has never been about whether we can survive or not, but keeping damages and costs to a tolerable level. The IPCC concluded in 2007 that we risk billions more people being short of water due to climate change, and hundreds of millions at risk of flooding and hunger. That is a lot of suffering, but not the end of civilisation.
There is a strong emerging view, proposed by the IPCC in its latest assessment in 2007, that a careful mixture of mitigation (reducing emissions) and adaptation will be necessary to meet the challenge of climate change. And this is broadly accepted by governments now striving for agreement by the end of next year. The polarised views of both Tickell and Lomborg miss this completely. We know we cannot avoid some serious climate change (our vacillation over the past 10 years has put paid to that), but we can avoid the worst of it. At a minimum we will have to adapt to about 2C of warming. The choice still available to us is whether we should try to avoid more than this amount of warming. Common sense suggests we should, since we do not really know what impacts the future holds, and we risk repeating the mistake of the movie producer Lew Grade who, looking back on the mounting losses of his film Raise the Titanic, concluded: "It would have been cheaper to lower the Atlantic."
· Martin Parry led the 2007 assessment of impacts and adaptation by the IPCC martin.parry.ipcc@googlemail.com
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