The environmental problems posed by road transport and discussed i n this part of the book are organised i n terms of the geographical domain of their effect. The only global effect of road transport resides i n its contribution to the so-called enhanced greenhouse effect resulting i n possible changes i n the earth's climate. Al though the U K ' s contribution to the total emissions is small, the U K , along wi th al l other developed countries, has committed itself to restraini n g future emissions and road transport is one sector w h i c h contributes significantly to overall emissions.