From Populations to Ecosystems: Theoretical Foundations for a New Ecological Synthesis

The human species is arguably at a turning point in its historical development. In a few millennia, humans have risen from the state of sparse populations of gatherers-hunters with minor impacts on their environment to that of a global collective force that is reshaping the face of Earth. The fate of our planet hinges to a significant extent on how humankind will handle its new status of global dominant species and adapt its behavior and society accordingly during this century. The global human population and economy are still growing nearly exponentially today. One of the most striking and yet poorly appreciated properties of exponential growth is that a population can grow in absolute terms as much in a single generation as during its entire previous history. By contrast, planet Earth has a constant size. Since the fraction of land transformed or degraded by humanity was estimated to lie somewhere between 39 percent and 50 percent more than a decade ago (Vitousek et al. 1997), humankind could easily destroy all remaining “natural” or unmanaged ecosystems during this century, with devastating consequences for biodiversity, global biogeochemical cycles, the global climate, and, indirectly, humans themselves. Whether we like it or not, a global environmental crisis lies before us with certainty—in fact, it has already started. What is less certain, and gives a glimmer of hope, is how humanity will face this crisis. Any crisis is an opportunity to transform oneself. If humankind manages to radically change its social relationships and its relationship to nature, it can establish a new balance within nature that meets its own needs while preserving the resources and beauty of the natural environment in which it has grown (Loreau 2010).

The global environmental crisis we are entering has several components. Chemical pollution and now climate change have attracted a lot of attention from both scientists and the general public, in part because they are relatively easily measured and monitored. But perhaps an even greater challenge is the future of life and its diversity on our planet (Wilson 1992,

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