TWO degrees Celsius. That increase in global temperatures has become synonymous with 鈥渄angerous climate change鈥�. Lobbyists haggle over it, scientists build models around it and Greens wring their hands over it. So it is dispiriting to learn, with the next round of United Nations negotiations under way in Durban, South Africa, that many climatologists feel it is a target we are almost certain to miss.
Is it time to set a new target? Two degrees was not selected by the Intergovernmental Panel on Climate Change, which merely set out the effects of different temperature changes. Rather, it emerged as a political consensus in 2007, culminating with its inclusion in documents produced at the UN negotiations in Bali, Indonesia. For some, such as the residents of low-lying islands, 2 掳C is already too much. For others, it will be expensive but manageable (see 鈥淲armer world is the challenge of a generation鈥� and 鈥淓arth in balmy 2080鈥�).
We should proceed with caution. Discarding or relaxing the 2 掳C target would set the wrong tone for future negotiations. Every further fraction of a degree by which the temperature rises represents a failure of political will. It should feel like it.
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