Suburbs may on the surface look fresh, green and full of trees, but living a green lifestyle is, in fact, far easier in the city. The main reason is of course transportation. Suburbs consist of homes isolated from everything else, including workplaces, shops, leisure facilities, hospitals, and schools.
To do or buy anything you have to make a trip, and to make this trip you have to burn fuel. Even where public transport exists it too uses energy, albeit far less per person than automobiles. Usually there is not even this option. You have to drive.
All these people making long car trips to and from the suburbs every day pumps a tremendous amount of carbon emissions into the atmosphere. The air pollution that leads to childhood asthma and adult bronchitis is not usually caused by dirty factories any longer. It is caused by cars, and most of it comes from suburban travellers. This also adds to serious global issues such as acidification of the oceans and climate change.
People who live in the suburbs yet want to be green might have a difficult time finding alternatives. Modern suburbs, especially in the United States, are built on the assumption that everybody will, and wants to, drive. Public transport is minimal, cycling on the roads is likely to be extremely dangerous, it is way too far to walk (and chances are there won’t be sidewalks anyway) and people too spread out for car pooling to often be an option.
In the city, however, things are far closer together. You could probably walk or cycle to just about anywhere you want to go. City centres also have rather better public transport networks making this a viable option. The numbers of people using them also make this option a greener one.
There are a few less obvious reasons why being green in the city is easier than in the suburbs. One is related to the size of accommodation. Houses are bigger in the suburbs and they consume more energy to heat or to cool. Building them in the first place requires more raw materials. People in the city use less space per person, and with this they are already consuming less without even trying.
Another aspect is that specialist shops selling organic produce, organic delivery schemes, and smaller businesses are easier to find in the city. Living in the suburbs you are pretty much restricted to the nearest enormous supermarket. Getting there uses yet more fuel, these places are often less than ethical businesses, and you will always be tempted to buy way more than you need every time.
In the city, you have more choices, you can support smaller companies, and of course if you are walking or cycling you can’t buy too much at once. You just won’t be able to carry it, so temptation is not even an issue.
However don’t despair if you are stuck in the suburbs and struggling to be green. There is plenty you, and your neighbours, can do that would make a huge difference. The main one would be putting pressure on local authorities to provide alternatives to driving, whether this is cycle lanes or a regular bus service.
The latter can actually be profitable, whether for a private owner or local government, which is a good argument to support your case. Also investigate other ways to reduce the driving you all do, for example by having a shopping rota. Being green might be easier in the city but it is possible in the suburbs too.