By Theodore Endreny
Megacities are on the rise. There are currently 47 such areas around the globe, each housing more than 10 million residents.
More than half the global population now lives in urban areas, comprising about 3 percent of the Earth. The ecological footprint of this growth is vast and there’s far more that can be done to improve life for urban residents around the world.
When it comes to natural spaces, trees are keystone species in the urban ecosystem, providing a number of services that benefit people. My research team has calculated just how much a tree matters for many urban areas, particularly megacities. Trees clean the air and water, reduce stormwater floods, improve building energy use and mitigate climate change, among other things.
For every dollar invested in planting, cities see an average of US$2.25 return on their investment each year.