* Tel.:#0091 22 840 0919/0920; fax:#0091 22 840 2026/2752; e-mail: ramanathan@igidr.ac.in Global Environmental Change 9 (1999) 203 } 210 Selection of appropriate greenhouse gas mitigation options R. Ramanathan* Indira Gandhi Institute of Development Research, General Arun Kumar Vaidya Marg, Goregaon East, Santosh Nagar, Mumbai - 400 065, India Received 12 June 1998 Abstract Greenhouse gas mitigation options help in reducing greenhouse gas emissions so as to avoid the adverse environmental impacts due to global warming/climate change. They have di!erent characteristics when evaluated using di!erent criteria. For example, some options may be very cost e!ective, while some may have an additional advantage of reducing local pollution. Hence, selection of these options, for consideration by a national government or by a funding agency, has to incorporate multiple criteria. In this paper, some important criteria relevant to the selection are discussed, and a multi-criteria methodology is suggested for making appropriate selection. The methodology, called the Analytic Hierarchy Process, is described using two illustrations.  1999 Elsevier Science Ltd. All rights reserved. Keywords: Climate change; Greenhouse gases; Mitigation; Selection criteria; Analytic hierarchy process 1. Introduction It has been recognized during the past decade that growing atmospheric concentrations of greenhouse gases (GHGs) originating from human activities may lead to catastrophic environmental impacts due to global warm- ing/climate change. Hence, e!orts have been directed towards identifying acceptable greenhouse gas mitiga- tion (GHGM) options, which will reduce GHG emissions so that the adverse environmental impacts are avoided. Several GHGM options have been identi"ed over the last many years. Some of the options for mitigating carbon dioxide (CO  ) (a major GHG) in the energy sector include: use of emerging e$cient technologies for new power plants, modernisation of existing power plants, renewable energy technologies for power genera- tion, fuel switch to less carbon-intensive fuels (e.g., from coal to natural gas), shift to non-carbon fuels (e.g., nuclear power), reduction of transmission and distribution losses, system optimisation techniques (e.g., the integrated operation of grids), e$ciency improvements through fuel upgradation, and, use of demand side management options (Painuly, 1997). Similarly, some GHGM options for the transport sector include alternative less carbon emitting fuels, electric vehicles, e$ciency improvements (e.g., conversion of two-stroke engines to four-stroke engines, electronic engine management, transmission im- provements, weight reduction, aerodynamic improve- ments, improvements in tyres, lubricants and accessories, etc.) and improving the modal split in favour of more energy e$cient and environmental friendly technologies (e.g. the railways) (Ramanathan and Parikh, 1996; Sagar, 1995; Hughes, 1991). Obviously, when evaluated using di!erent criteria, these GHGM options show di!erent characteristics. Cost e!ectiveness (measured for example in terms of cost of reduction by one tonne of CO  or any other GHG) associated with these options will be di!erent. Some of them may provide bene"cial side e!ects while some may have adverse side e!ects. For example, substitution of vehicles driven by petroleum products by electric vehicles can also reduce local pollution on the roads. Encourag- ing nuclear power generation may reduce GHG emis- sions, but may have adverse implications in terms of harmful radioactivity and waste disposal. Some options may not be politically or culturally acceptable to some countries. Some options may be very cost e!ective, but their implementation will be di$cult. Selection of appropriate GHGM options is thus a complex problem. It is necessary to consider several 0959-3780/99/$ - see front matter  1999 Elsevier Science Ltd. All rights reserved. PII: S 0 9 5 9 - 3 7 8 0 ( 9 8 ) 0 0 0 3 9 - 9