Topics like these always make me think of the Planet Earth series. They called the world's rain forests "the lungs of the world" because of how crucial they are in cleaning and replenishing our atmosphere. Our ecology is essentially in a balance where the CO2 absorbed during the wetter seasons is released during the dryer cooler seasons when plants shed parts that decompose, releasing CO2. Our oceans also absorb CO2,helping keep the atmosphere keep balance.
So urban development and it's resulting waste products like, CO2, resource depletion, pollution, and trash, upset this balance by adding excess into this equation that the ecology simply can't process.... or rather processes it in a way that's bad for humans(and other species). So urban development as it is now, urbanism as it is now, society as it's built and maintained now, these systems are responsible for climate change. I think it could be done sustainably, but that's a whole other topic I guess haha