At least 20 % of government transport budgets should be invested in infrastructure for walking and cycling , according to the United Nations Environment Programme ( UNEP ) . Such infrastructure would reduce pollution and emissions whilst also saving lives . A quarter of all global carbon emissions are caused by motorised transport , which is the quickest - growing transport sector . The world’s fleet of private cars is forecast to triple by 2050, with most of the growth in developing countries. This type of transport is expected to cause a third of all emissions by 2050 , with the number of private cars tripling by 2050 . UNEP argues that the growth , primarily in developing countries , will damage the world ’s ability to achieve the terms of the Paris Climate Agreement .
At least 20 % of government transport budgets should be invested in infrastructure for walking and cycling , according to the United Nations Environment Programme ( UNEP ) . Such infrastructure would reduce pollution and emissions whilst also saving lives . A quarter of all global carbon emissions are caused by motorised transport , which is the quickest - growing transport sector . This type of transport is expected to cause a third of all emissions by 2050 , with the number of private cars tripling by 2050 . UNEP argues that the growth , primarily in developing countries , will damage the world ’s ability to achieve the terms of the Paris Climate Agreement .