A method of re-establishing the critical carbon sinks around the world in order to balance the destructiveness of human development is that of planting urban forests and managing their growth and care. This vision of nature coexisting with human development instead of being subservient to it is beginning to take hold. What easier thing than to flow with the energy cycles of nature that provide water, oxygen, shade and food to the local climate regions? The principle that life adapts to the available resources is not only universal, but critical to the balance of nature.
There are examples of this urban forestry taking hold through community cooperation with government policies. The city of Johannesburg in South Africa has been documenting, managing and growing its massive urban forest since 2000. It is one of the largest urban forestry projects existent, to the point that it has regenerated lands that were previously barren:
On satellite pictures, the city looks like a rain forest, albeit man-made, but because the city does not get the required amount of rainfall to qualify as one, it passes as an urban forest. In the 1860s, when trekkers first settled on the Witwatersrand, there was not a tree in sight, and the area of rocky grassland was dotted with the odd shrub and several streams.
This was achieved with partnerships by many entities, public and private, and includes, by necessity in all urban reforestation efforts, a public re-education about the actual value that trees in managed ecosystems can provide.
Another one of the oldest and largest urban forests is in Rio de Janiero and its environs. Interestingly, the deforestation caused by human development generated an outcry in 1658 because of the degradation that impacted the water supply; without the trees that had created the natural forest, the wetlands dried up, as did the water supply. So in 1860 it was mandated that the barren hills be reforested with native plants and trees. It's an impressive story, but the warning is that 400 years later the forest has still not recovered its natural biodiversity, so the wild and natural forests are not yet able to maintain natural systems. This means that the natural regenerative mechanisms are still not back in place, and it's incumbent on us to take this to the next level - which is to pull back from the edges and allow natural regeneration to happen. More recent, urgent issues are created by political events in Brazil - In 20 years, Curitiba, Brazil has increased the green space per inhabitant from 0.5 to 52. The intention was to plant one and a half million trees in 20 years for, since the 1988 murder of Chico Mendes (the campaigner to save the rainforest), Brazil had been on the defensive in ecological circles.
Many communities worldwide foster their urban forest in an informal way with guidelines and arguments for citizens to cooperate in keeping the urban tree canopies healthy and promote undergrowth such as shrubs and mulch. It's a much more natural feel than you'd find in typical suburban roof farms that are acres of asphalt and a few scraggly trees captured in concrete sidewalks. This form of cancer can and should be reversed for the sake of sustainable habitation.