April 24, 2006

Part II: Planetary-scale Patterns

Auditing the Earth: Present Changes,
Future Changes, and Irreversibility
Stuart Pimm, Duke University
35 min. (slideshow requires QCShow Player)
Audio only (mp3 format)
View as a webpage (quicktime, real player) (notes)

"Man eats Planet! Two-Fifths Already Gone!"

Stuart Pimm uses this headline as the title to one the chapters in his 2001 book, The World According to Pimm, and he recapitulates many of the planetary-scale lessons from that book in this week's lecture.

When talking about this subject, it's easy to slide into alarmist hysteria, but even under the most rational and calm discussions the numbers are still staggering. Humanity is clearly transforming the face of the planet. We now use 50 percent of the world's freshwater supply and are consuming 42 percent of the world's plant growth. Simultaneously, we are destroying the tropical moist forests of the world, the reservoirs of the world's biodiversity. Indeed, they may be gone in as short a period as 20 to 30 years.

The effect that this is having on the planet's biodiversity is that we are extinquishing animal and plant species 100 to 1000 times faster than the natural rate of extinction. Such numbers should make it clear that the human impact on our planet has been, and continues to be, extreme and detrimental. Planetary-scale ecology may be rapidly eclipsing economics as the "dismal science."

Yet even after decades of awareness of our environmental peril, there remains passionate disagreement over what the problems are and how they should be remedied. Much of the impasse stems from the fact that the problems are difficult to quantify.

How do we assess the impact of habitat loss on various species, when we haven't even counted them all? And just what factors go into that 42 percent of biomass that we are hungrily consuming? It is only through an understanding of the numbers that we will be able to break that impasse and come to agreement.

While it's in Stuart's nature to be an optimist ("unashamedly optimistic" is how he describes himself), the implications of the numbers he presents are nonetheless alarming. But without being an optimist, change for the better probably isn't possible.

— Wirt Atmar

About the Speaker

Stuart Pimm the Doris Duke Professor of Conservation Ecology at Duke University. Stuart became a conservation biologist after watching species go extinct in Hawaii in the 1970s. That experience led to his commitment to study the scientific issues behind the global loss of biological diversity.

Pimm has written nearly 200 scientific papers, including three review articles in the journals Nature and Science. He has written three books: The World According to Pimm: A Scientist Audits the Earth, Food Webs, and The Balance of Nature?: Ecological Issues in the Conservation of Species and Communities.

Pimm's research covers why (and how quickly) species become extinct, the global patterns of habitat loss and species extinction, the role of introduced species in causing extinction, and, importantly, the habitat-management consequences of this research.

Stuart's current work includes studying endangered species and ecosystem restoration in the Florida Everglades, setting priorities for protected areas in the Atlantic coast forest of Brazil and for savanna ecosystems in southern Africa, and tracking jaguars in the rain forests of Central America and fossas in the dry forests of Madagascar.

Pimm also carries the title of "extraordinary professor" at the Conservation Ecology Research Unit, University of Pretoria, South Africa.

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