What's today's most unprecedented impact of people on the planet? Climate change? Maybe, though the planet has witnessed massive swings in climate through geologic time. The loss of species? Tragic, but species have been going extinct as long as they have been evolving. Today, we are living through an unparalleled, demographic upheaval. We are now an urban species, and in the next few decades nearly 7 out of 10 people in the world will be living in cities. The impact reaches far into nature and how people get food, water and other resources to support urban life. Our transformation to an urban species could spell more disasters for the planet, or it could be our saving grace.
Beginning about ten thousand years ago, our species made a momentous transition. Instead of foraging and hunting for food, people began to cultivate plants to eat and domesticate animals for meat, dairy and labor. The change in lifestyle from food-gathering to food-growing set civilization on a new path. Complex societies with stratified hierarchies evolved, similar to other farming species such as leaf cutter ants and termites.
The growth of economies, trade and industrialization of food production over the next ten millennia propelled civilization into a new survival strategy that is unique to our species. As of 2007, the majority of people in the world live in towns and cities and get their subsistence from food produced by a minority. Just a century ago, 85 out of 100 people lived in rural areas and grew much of their own food. This dramatic shift in lifestyle reverberates to all corners of the planet. It fundamentally changes how people relate to nature and how nature responds to people.
Nearly all the growth in the world's population, from the current 7.3 billion to about 9.5 billion by mid-century, will be in cities before leveling off. Like the urban boom of Europe's Industrial Revolution in the eighteenth century, Africa and Asia are quickly shifting from agrarian to urban-based economies. Is this urbanization of our planet good news or bad?
For those who depend on nature to provide clean water, purify the air or recycle our wastes -- in other words, every living being -- the transformation might seem to be bad news. Though cities and towns cover a paltry few percent of the land surface, their tentacles extend far and wide. Cities consume the lion's share of the world's energy. Wealthy urban dwellers gobble up a disproportionate share of food and luxuries. Many of these luxuries -- coffee, chocolate, bananas and pineapples to name a few -- come from the tropics where remaining forests and other wild places are the last hope for the survival of orangutans, tigers and many other uncounted, less charismatic species. In cities, a trip to the grocery store hides our dependence on the soil, climate and farmers in these far-away places. A turn of the tap obliterates the long journey of water through forests, soils and streams to filter out impurities. City life, the argument goes, severs our links with the very nature that makes life possible.
There's another way to view the implications of the massive urban shift in the world's population. Cities concentrate the place of consumption. Instead of millions of scattered, individual villages and households each scraping together enough energy and food to get by, resources from the countryside funnel into cities. Vermont, New Hampshire and upstate New York, for example, were nearly bald of tree cover a century ago. As people moved to cities for industrial jobs, coupled with transport of foodstuffs from the Midwestern prairies, they abandoned the less productive farms in the northeast. Trees, bears and other signs of nature have made a comeback.
The opportunities are immense for our urban existence to benefit the planet. If -- and this is a big if -- people in cities demand that the products they consume don't mow down rainforests, pollute waterways or spew out greenhouse gases. Re-wilded places can filter water, store carbon, provide homes for other species and carry out the multitude of other benefits that nature provides. They can provide solace from urban life and places to recreate.
There are signs that the "big if" could be a reality rather than a pipedream. Just within the last few years, companies ranging from Cargill to Dunkin' Donuts have pledged that their supply chains will only use sustainable sources. Donuts will not be fried in "conflict" palm oil that destroys forests and usurps local communities' rights to the land. Walmart, through collaboration with the Environmental Defense Fund, has committed to purchasing grains from farmers who do not use excess fertilizers that run into waterways and emit potent greenhouse gas. Brazil, one of the world's agricultural powerhouses, has slashed its deforestation rate by nearly 80 percent over the last decade while increasing its production of soy and meat.
Countries like Costa Rica show the possibilities for reducing forest loss and turning a profit from nature-based tourism. If urban consumers can satisfy their demands without trampling on faraway, unseen places that produce the goods they consume, the future could protect nature even though their daily lives seem disconnected.
City life brings its own share of problems. Air pollution plagues many cities of the developing world. Urban diets of processed, sugary and fatty foods are fostering obesity and heart disease and threatening the health of growing urban populations in China, India, Mexico and elsewhere where economies are growing rapidly. Roads and housing cannot keep pace with the influx of people from the countryside. With the rush to adopt high-consumption lifestyles, the gains in holding private-sector producers responsible for their supply chains and governments accountable for protecting wild places could slip.
Despite the pitfalls, there's no going back to the agrarian existence of the past. Our urban future is all but inevitable as economies grow and people flock to cities. But our existence as an urban species, the first of its kind in the several billion year history of life on this planet, is uncharted territory. Rather than decry this new way of being, we can embrace this future as an opportunity to repair nature.