Contraction And Convergence

The ''contraction and convergence" framework proposes to bridge the gap in per capita emissions between developed and developing nations within a few decades. Its main aim is to specify the long-term pathway for evolution of national emissions of CO2 that would converge at a common per capita level. The proposal typically involves two steps. The first specifies a global emissions pathway for each year, corresponding to a stabilization target for a long-term CO2 concentration level such as 550 ppmv (parts per million volume) by the year 2100. The second allocates annual emissions limits among nations for per capita emissions to converge at an agreed-upon date in the first half of the century. This proposal reflects "grandfathering" and "equal per capita emissions entitlement" principles.

Prima facie, the compromise reflected in this proposal appears practical and acceptable, since "grandfathering" suits the present needs of developed nations and "equal per capita emissions entitlements" fit well with the demands made by developing countries (Agarwal & Narain, 1991). Fairness is not the natural outcome of the framework; it is, rather, a function of the parameters of the framework: the convergence limit and the rate of convergence. Thus, the equity conflict is pushed to another domain, that of agreeing to these parameters. Unless these parameters are agreed on in a fair manner, the result could contravene accepted equity principles like the obligation to pay, Rawlsian (Rawls, 1971) criteria, and welfare maximization.

The per capita emissions gap between the developed and developing nations today is very high (see Fig. 1). Under the business-as-usual approach, in a few decades, the per capita emissions of a developing country could cross the emission limit, and from then on that nation would be a net buyer of emissions entitlements. Early entry of a developing country into such a binding commitment, which is likely to happen under the conventional conception of convergence (Jepma & Munasinghe, 1998), could be doubly inequitable if convergence pathways are constructed presuming that the per capita emissions trajectories of developed and developing nations will converge without crossing the target (Fig. 2a). Such convergence would make developed nations the net gainers of emissions entitlements (Fig. 2a, Area A) and developing countries the net contributors (Fig. 2a, Area B) for all times - past and future.

The income effect (see Kuznets, 1955) is likely to cause the per capita emissions from the developed countries to transition to a declining trajectory earlier than in the developing countries. In later periods, developing countries will experience a rising burden associated with buying entitlements or incurring mitigation costs. For instance, the present per capita carbon emissions from China are 0.7 tons of carbon, and these emissions are rising rapidly. The enforcement of a stabilization requirement, such as 550 ppmv (Wigley et al., 1997), would require the convergence limit to be below this trajectory later in the century. Even if the limit were set in the earlier period at a higher level, say at around 1 ton of carbon per capita, China would

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Fig. 2. Convergence Pathways of per Capita Emissions (Stylized Representation). (a) Conventional Convergence Concept. (b) Just and Equitable Convergence Profiles.

become a net buyer of entitlements within this decade or would have to incur significant emissions mitigation costs for transitioning to a lower carbon emissions trajectory. This situation could be unfair from the perspectives of both historical responsibility and ability to pay, given China's low historical per capita emissions and income.

A more equitable convergence scheme (Shukla, 1999), from the perspective of developing countries, may follow the trajectories shown in Fig. 2(b). The developing country per capita emissions can first cross and then converge to the target level, while remaining on a downward path that follows an environmental Kuznets curve. (The reference to Kuznets curves is linked to Kuznets' empirical observation that income inequality tends to first rise and then fall in the course of economic development, yielding an inverted U-shaped curve between per capita income and inequality or, by extension, environmental performance.) Alternatively, fairness would require dynamic targets that at first allow rising and then declining trajectories for developing countries so that they earn and bank entitlements for later use.

The contraction and convergence framework is useful for reconciling the divergent interests and views of nations on the basis of their diverse per capita emissions profiles. This framework limits equity measurements to two simple parameters and can, therefore, facilitate comparison of alternate equity formulations. However, it is neither an instrument for cooperation nor a mechanism for creating equitable solutions.

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