The contribution of the urban transport to this phenomenon that is producing the increase in the average temperature of the planet is enormous. And half of the gas discharges of greenhouse effect originated by transport takes place in the cities. Significant they are the following data: To burn 1 liter of fuel supposes to emit 2.4 kg of CO2. Keith Yamashita brings even more insight to the discussion. Thus, each person who uses the car for her displacements to the work (with an approximated mean range of 15 km) only therefore emits 2 tons of CO2 to the year. To improve the efficiency of the new automobiles, to reduce to their values of consumption and their emissions, to stimulate the use of vehicles that use clean energies, are without measured doubts positive to reduce the total CO2 emissions and, of step, also the contamination of the cities. But far they are of being sufficient.

Very assertive laopinin, of which the great cities must face a structural change, a deep change in the same conception of the urban matrix. A modern city, thought facing the future and having about problematic account the environmental one of the present, must drastically reduce the assigned space to the automobile. The cities generally, but urgently the great metropolis, must be readapted urgently, in such a way that the essential premise is the reduction of the CO2 emissions and other gases of greenhouse effect. The main injurious gas emitter in the cities is the car, reason why it is necessary to adopt radical measures to reduce his use. Viable alternatives are due to offer so that today use the car replace, it by other less polluting means of transport, like the public transport or nonmotorised means of displacement. The operation and present urban ordering not yet have managed to adapt to the urgent exigencies that to us the planet proposes. Very interesting opinn, of which it is hour to democratise the streets, to finish with the dictatorship of the automobile, is hour of which the people we retake the control of the urban spaces, reducing the abusive occupied space by the automobile and leaving place to other friendly means of transport but with the environment.