Introduction

It makes no difference for the climate whereabouts in the world greenhouse gases (GHGS) are emitted or absorbed. Since emission reduction measures can be taken anywhere, their potential and cost-effectiveness is not determined by the specific national situation, but by the global situation. From a technical point of view, therefore, emission reduction as a solution to the climate problem is a global challenge. This chapter therefore looks at emission reduction as a technical strategic issue from a global perspective .

The magnitude of the emission reduction challenge is dictated by the contributions of the various greenhouse gases, their sinks and the anticipated increase or decrease in emissions over time. The following questions are central here:

• • What are the main sources of emission and absorption in terms of their magnitude and dynamics, by sectors and by countries/continents?

• • How far would emissions have to be curbed in order to achieve the European Union's (EU) 2°C target?

• • Within what timeframe would emission levels have to be reduced?

If we focus on emission reduction policy, in what directions do we need to look for solutions:

• • What are the main technical options as regards reduction potential and maturity? The more pressing the time, the greater the need for available technologies which can be fitted into existing systems and practices.

• • How cost-effective are the various options? The importance of cost-effectiveness increases as the need to engender support for climate policy spreads to developing countries.

• • What is their synergy with other options, so that options can benefit from each other, and what synergy do they show with other social objectives such as security of energy supplies and economic development?

• • Does today's knowledge offer a reasonable perspective of timely emission reductions in the first half of this century?

This chapter is structured as follows. Section 4.2 translates the EU's 2°C target into an emission reduction programme for CO2 and other greenhouse gases (OGGS) for the next fifty years and shows the gulf compared with a BAU (Business As Usual) situation.