5.4 Contraction and convergence
However it is achieved, avoiding dangerous climate change requires industrialised nations to cut emissions by at least 80% (some estimates cite a figure of 95%) while developing nations grow their economies. One proposed global framework is contraction and convergence (C&C), which was conceived by the Global Commons Institute in the early 1990s.
C&C consists of reducing overall emissions of GHGs to a safe level (contraction), with global emissions being reduced because every country brings emissions per capita to an equal level (convergence). The first stage of implementation is a contraction budget for global emissions consistent with stabilising atmospheric concentrations of greenhouse gases at a pre-agreed safe maximum concentration. C&C is favoured by the European Commission, European Parliament and many other government bodies; and with the contraction aspect reducing total carbon emissions, it is supported by many campaigners (including George Monbiot cited above). Supporters of C&C, such as the Climate Justice Project, believe that the safe maximum is much lower than other estimates. Specifically, they believe that the IPCC's safe estimate of 550 ppmv CO2 is wrong and risks entering a phase of runaway ‘climate feedback’, with one change causing another with unpredictable results. They advocate a more precautionary approach, with atmospheric CO2 being stabilized at 350–450 ppmv. In the UK, to reach these targets, individuals' emissions would need to be cut by between 60% and 90%.