Despite being able to use many different public transports, we mostly use private transport. Research shows that climate problems are caused from many differnt factors, but air pollution is thought to be the main factor, meaning improvements in ways of transport will lead to some kind of solution.
Firstly, we now use our own vehicle where each families usually have one to two per households. In other words, families with two or more private vehicle is likely to produce more than twice as many pollutant compared to families using public transport depending on their family size. Therefore, developing public transport as a common method of transport, it is more probable that issues related to climate change will reduce and display positive outcomes. Furthermore, the increased use in public transport will deduce the amount of traffic occuing in busy cities, allowing reduction of pollutant produce per time.
However, private vehicles used in a standard households are mainly hybrid cars or in some developed countries, electric cars are increasing its number. This suggests the reduction of CO2 emission, letting the use of public transport being less meaningful.
In conclusion, carbon emisson from vehicles is the biggest factor of the environmental issues in cities, improving public transport will likely be contributing to some solutions for the enviornmental problems in some kind of way.