It is a well known fact that cities are often as much as 5 degrees hotter than the surrounding area. This is for a variety of reasons.
A new study looked at 2000 cities around the world and found that a mixture of tree planting, rainwater gardens and de-paving can mitigate almost all of the extra heat likely coming because of global warming.
It is estimated that cities have been warming by around 0.5 degrees Celsius each decade (on average) – which has been found to be around 29% faster than in rural areas. More alarmingly, for the emergence of mega cities in places like china, is the fact that these cities are seeing these problems to an even greater degree.
However, the study found, that where tree planting occurred a cooling effect was felt. Trees also have other incredibly important factors, such as their ability to capture micro particles from the air (they settle on the plants leaves, and are then washed down the drain when it rains) which bring many positive impacts for humans living nearby.
It is true that humans have roughly halved the number of trees on earth, and that there is not the space to replant them all (with the space humans currently take up) however, there is likely space for billions more trees in the worlds cities – something that could soak up many billions of tonnes of carbon, as well as improving health and wellbeing for people all over the world.
Whether this will happen is another question. It is likely that some parts of the world people will do what is sensible, but in other places it might be quite different.