Sharply reducing the number of cars in cities in favor of public transportation could cut carbon dioxide emissions by around 40 percent by 2050, a new study has found.

The study from the University of California and the Institute for Transportation and Development Policy said promoting walking, cycling and using public transport instead of cars will be the most effective way to reduce pollution in urban areas, Reuters reported.

"While every part of the global economy needs to become greener, cleaning up the traffic jams in the world's cities offers the least pain and the most gain," said study co-author Michael Replogle of ITDP, as quoted by Reuters.

CO2 emissions will probably rise fastest in developing countries. According to Replogle, more public transport in growing cities will additionally offer more job opportunities.

"It is clear that the success of developing good public transport in wealthy countries has come by governments establishing systems for greater private investment in public transport," he told the Thomson Reuters Foundation.

"That has not been happening as effectively in much of the developing world, but this report describes the framework in which it could happen."

Implementing more public transport would be extremely cost-effective, saving economies some $100 trillion in costs; it would also be safer, reducing the yearly premature death toll by around 1.4 million, according to the study.

What is the next step toward an urban landscape that doesn't include bumper-to-bumper traffic?

"What's needed is for governments to work with development banks and other institutions to help give a green light to the kind of projects that can reallocate street space to favor public transportation, bicycles and walking," said Replogle, as quoted by BBC News.

"Unlike energy strategies that require investment in more costly technologies, this is a set of investments that simply require investing in better public transportation and making streets safe to walk and bike."

See Now: OnePlus 6: How Different Will It Be From OnePlus 5?