Most of the time, roofs are not used for anything but keeping our heads warm and safe.  On the tops of buildings and schools can be little gardens that can eventually be transferred to the ground.  We can also do things like fish farm on top of roofs.  They are good because they are right under the sun, they fight the pollution problem, and there is easy access to healthy foods.

Great point you brought up! When we build buildings, we are taking away space where something else used to live. This could be a number of plants and animals. If we added a garden to ever top in some big city, the buildingings themselves would be filtering out Co2 from the air. Simply adding a few trees or even planting a garden that's supplying us food could be a great step towards cleaner air, and local food in places you usually can not get that.

Great point Kayla, and to clarify, will the gardens on the roof have covers or drains to keep water from overflowing. Let's just say it rains one day, all the water will flood the plants from being stuck on the roof. So how would you monitor how much water the plants get?

This is a really good idea, that could be made a huge part of all city skylines across the world. Most of the time in cities there aren't that many trees, besides in parks, mainly because they were all cut down to make room for buildings. This idea brings back nature to the city, as well as limiting the cities carbon footprint. I also love the idea of using the gardens as a food resource to people, cutting down their carbon footprint as well. This sadly wouldn't work for my are since I live in a small town without any flat top building, but incorporating more gardens into our lives is a step that we need to make.

I think rooftop gardens is a great idea because it allows people who live in urban environments a chance to sustain themselves instead of being completely reliant on grocery stores or restaurants. Grocery stores have pesticides on their produce and the quality of the food is much lower than what you would get in a standard garden. Because urban environments do not usually have gardens, rooftop gardens are a innovative idea into making the world greener.

Rooftop gardens are also useful in terms of conserving space. Since Earth's population is growing more and more each day, it's not practical to grow plants for food outside of cities. The CO2 emissions from transporting the food to the cities will damage the environment, and eventually, the cities would expand all the way to the farms. By building rooftop gardens, people can conserve space, grow organic food, and contribute to helping lower the amount of CO2 in the atmosphere.

@Aidan M (USA) BOD3MCW   
To answer your question, I really think its depends on where you are in the world.  There would be no reason to stop overflow if the garden is in a dry area with little to no rain.  However, in places with a lot of rain, a cover should be used at certain intervals so some rain can be used.  To make sure there is no flooding, we can use the thing on almost every building: drains.  Drains take the excess water away so there is no flood, but the water a plant needs will get to the plant.  The pots that a plant is in can also have some holes to let out water.  You would have to monitor the garden just like every other garden, because other gardens can flood as well.  A few adjustments just have to be made.

I believe this is a great idea for a small changes for a small city but I doubt it would be enough to make a vast change

I disagree @youcanfindanythinginchinatown , if he entire country of even just a couple states took advantage of this idea, not only would it help make clean air, it would also decrease the need for processed food. For example, if a school were to participant in this, they could use fresh fruits and veggies from their garden rather than have to buy sub par versions of those foods, filled with pesticides and chemicals, for the students. It would also eliminate waist in schools, because instead of having to throw away unused products, they could simply take as much as they needed without having to estimate in advance. As far as School goes, this could also be an awesome way to give children who live in big cities an opportunity to work in agriculture. I've also seen some of your other posts and I do believe that "going back to the primitive times" is quite unreasonable, however this is one step closer and WOULD in fact make a HUGE difference in America.

i love the idea of growing food on your roof because it is a sustainable way to get food and an easy way to absorb the sun.

Rooftop gardens is a popular idea amongst conservationalists, mainly because it provides a natural carbon output within urban environments. Cities have little opportunities to save carbon- it's hard to live in an environment where everything everywhere is man made and attempt to lead an energy efficient lifestyle. However, using the free space on the roofs of apartments and office buildings, people living in an urban environment have an opportunity to eat locally grown food (which eliminates the carbon produced by the process of transporting produce) and promote a clean atmosphere.