"As our numbers continue to grow, we continue to increase our need for far more water, far more food, far more land, far more transportation, and far more energy. As a result, we are now accelerating the rate at which we’re changing our climate. In fact, our activities are not only completely interconnected with, but are now also interacting with, the complex system we live on: Earth. It is important to understand how all this is connected. An increasing population accelerates the demand for more water and more food. Demand for more food increases the need for more land, which accelerates deforestation. Increasing demand for food also increases food processing and transportation. All of these accelerate the demand for more energy. This then accelerates greenhouse gas emissions, principally CO2 and methane, which further accelerate climate change. As climate change accelerates, it increases stress on water, food, and land. And at the same time, an increasing population also accelerates stress on water, food, and land. In short, as population increases, and as economies grow, stress on the entire system accelerates sharply."