Many ecosystems are dominated directly by humanity, and no ecosystem on Earth's surface is free of pervasive human influence. It has happened very quickly, and it already has resulted in unanticipated, major consequences. In their Science article, Vitousek, Mooney, Lubchenco and Melillo present an overview of the major ways that the human enterprise has transformed the planet, and suggest methods to manage this transformation so that the species and ecosystems we depend on can be sustained for the future. More than half of all accessible fresh water is used by humans. About a quarter of the bird species on Earth have been driven to extinction.
Humanity fixes more nitrogen from the air than is fixed by all natural processes combined.
While abundant usable nitrogen is good for crops, it also supports invasive species. Mooney, who is the Paul S. Achilles Professor of Environmental Biology, said that it is both the massive scale of global change and the rapidly accelerating rate of change that scientists are concerned about. We are changing Earth more rapidly than we are understanding it. That would involve slowing human population growth, and using resources efficiently so the wastes and byproducts of human activity do less harm to the environment. They also called for accelerated efforts to understand human-caused global change, with more ecological research as well as more work to understand the social, economic and cultural forces that drive human actions on the environment.