Global and Regional Greenhouse Gas Emissions Scenarios

The scenarios describe trajectories up to 2100 by four world regions. Today the distribution of both income and GHG emissions is very unbalanced between various world regions. Furthermore, the relative importance of individual gases and sources of emission differ from region to region. A feature shared by all scenarios is higher growth rates of population, income and GHG emissions in the current developing countries (DEV) than in industrialized countries (IND).

Today the DEV regions account for about 46% of all emissions, but by 2100 no less they contribute 67–76% of the global total. By that same year the total income generated in the DEV regions reaches 58–71% from only 16% in 1990. As a result of these two developments, GHG emissions per unit of income converge over time. Carbon emitted from fossil fuel use remains the primary source of GHG emissions over the next century; by 2100 CO₂ makes up 70 to 80% of total GHG emissions.

The role of sulfur warrants special attention. Contrary to many earlier studies, all scenarios presented here assume that sulfur emissions are controlled in all regions sooner or later, and to various degrees. As sulfur plays a role in cooling of the atmosphere through formation of sulfate aerosols, a local effect, this abatement constitutes a relative local warming effect. The decrease of sulfur emissions is already observed the IND regions, and is expected also in ASIA after an initial rise.