IMPLICATIONS OF RECENT CO2 EMISSION-LIMITATION PROPOSALS FOR STABILIZATION OF ATMOSPHERIC CONCENTRATIONS

The stabilization of atmospheric greenhouse-gas concentrations is the ultimate objective of the United Nations Framework Convention on Clima te Change. To investigate the gas emissions required to achieve this g oal for CO2 over the next few hundred years, the Intergovernmental Pan el on Climate Change (IPCC)(1,2) has used two sets of concentration pa thways ('profiles'). One set is based solely on smooth changes in emis sion towards concentration stabilization(3), and the other goes furthe r by incorporating economic considerations(4). Here I devise new profi les that take into account emissions-limitation proposals restricted t o 'Annex I' (developed) countries, as well as the constraints imposed by more recent emissions data (now available until the end of 1995; re f. 5). The Annex I scenarios considered are two that span proposals re cently considered by the IPCC6, and a less restrictive case. Using the new CO2-concentration profiles and a carbon-cycle model(7) to determi ne global CO2 emissions, and taking into account the prescribed Annex I country emissions, I determine the CO2-emission requirements for non -Annex I (developing) countries to achieve the stabilization of atmosp heric concentration at about twice preindustrial values, I show that a ction by Annex I countries within the bounds of the scenarios consider ed can mean that non-Annex I countries have several decades before the ir emissions need to depart significantly from a 'business as usual' ( no intervention) trajectory. Alternatively, if international trade in carbon emissions is permitted, non-Annex I countries can choose to emi t below their 'business as usual' baseline and benefit from the tradin g of emission rights.