Existing laws, regulations, and related activities like recycling, carbon-free energy resouces for electricity, but the Earth's temperature keeps increasing up to +1.5°C by 2040.
How about "More Oxygen" from green fields on the roofs of buildings?
Rooftop gardening may supply fresh fruits and vegetables specially creeping types. So, rooftop idea is good. If someone has enough space, he or she can start Commercial farming applying modern technology.
Green roof was actually use for keeping home warm during winter and cool during summer at the same time in urban areas the green roof also absorbs smogs.
Since the green roof reduces the building temperature it will help in reducing energy consumption.