The IPCC Third Assessment Report

New scenarios of future emissions of the various greenhouse gases and aerosols are currently being developed by Working Group III for the IPCC Third Assessment Report to be completed in 2001. Preliminary estimates that will be used in the newest climate model simulations have been made (H. Pitcher, Energy Modeling Forum Workshop, August 1998, Snowmass, Colorado; Nakicenovic, 2000).

These scenarios are formed differently from those of 1992. Basically, narrative story lines that include key scenario characteristics have been developed to describe a short history of a possible future development. The narratives explore what might happen if political, economic, technical and social development took particular alternative directions. From these narratives, quantifications are developed for the major factors that will influence emissions. These factors include population growth, gross domestic product and cumulative resource use. Four different macro-regions are considered: countries of the Organization for Economic Cooperation and Development (OECD), Eastern Europe and the former Soviet Union (EEFSU), Asia, and the rest of the world (ROW). The first two macro-regions represent developed countries, and the latter two represent developing countries. Interactions among industrialized and developing countries are particularly considered. There is neither a 'best guess' scenario (i.e. no probabilities are given for the four scenarios) nor an extreme 'disaster' one.

Scenario A1 describes a world with very rapid economic growth, low population growth, and rapid introduction of new and efficient technology. Scenario A2 describes a highly heterogeneous world with high population growth and less concern for rapid economic growth. Scenario B1 characterizes a convergent world with rapid change in economic structures, introduction of clean technologies, rapid technological development, and concern for global equity and environmental and social sustainability. Scenario B2 describes another heterogeneous world with less rapid and more diverse technological change. Scenario B1 has the lowest increase in total emissions of carbon by 2100; Scenario A1 has the highest. Scenarios A2 and B2 attain similar mid-range levels of carbon emissions by 2100. In all of these scenarios, sulphate aerosols are assumed to start decreasing before 2040, and in most of them, to start decreasing before 2030. All aerosols emission scenarios are considerably lower than the IS92a one. Aerosols essentially become relatively minor forcing factors by the end of the 21st century. These changes suggest less extreme scenarios than those of IS92. There still remains a set of scenarios based on the underlying economic and political assumptions, but the outer boundaries are narrower than those in earlier reports. Within the coming year, major climate modelling groups will use these emissions scenarios (once they are converted into concentrations) to generate new projections of climatic change to the year 2100.

Guide to Alternative Fuels

Guide to Alternative Fuels

Your Alternative Fuel Solution for Saving Money, Reducing Oil Dependency, and Helping the Planet. Ethanol is an alternative to gasoline. The use of ethanol has been demonstrated to reduce greenhouse emissions slightly as compared to gasoline. Through this ebook, you are going to learn what you will need to know why choosing an alternative fuel may benefit you and your future.

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