I think this kind of activities are crucial to warn people about our last chance. Actually a lot of scientists have different ideas about this topic. Firstly we should know that only one car-free day has a small impact on air pollution. In stead of this kind of short notice warnings, we must support pivotal activities which are supported not only governments but also huge conglomerates like big car firms. Secondly, in order to reduce car emission, our governments and local managers should enact important bills which are obeyed by all countries and world. Lastly, the green gas effect which is triggered by engines which are powered fuel or gas, should be eliminated step by step. These kind of cars or trucks or all vehicles should be exchanged with electrical motors or renewable energy using engines. At first glance we may out of limit to turn our predecessors time’s, but we should even struggle to reach some levels of their time’s carbon levels. So it is never be too late.