Musings, Explorations, and Announcements

UNEP published the Green Economy Report (GER) today.  I've been looking forward to reading this as it comes from the team that produced the impressive Economics of Ecosystems and Biodiversity Study (TEEB). TEEB aimed to be the "Stern report" for biodiversity, but it was very different piece of work.   GER, on the other hand, does something very similar to Stern - it lays out contrasting scenarios for global investment and explores their consequences.

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I've heard the song "Waltzing Matilda" many times but I only learned today the meaning of the word billabong - a long lake formed by a river jumping its bed. (In America we call them oxbow lakes.) The billabongs of Australia's Kakadu National Park are the site of a revealing ecological phenomenon reported today in Nature by Anthony Ives and colleagues.  Kariba weed, an invasive fern, arrived in the lakes in 1983, but has been kept somewhat in check through the deliberate introduction of the silvinia weevil.

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Many ecological systems have tipping points - thresholds where small changes in impacts can have very large effects on on ecosystem functioning, often in a bad way.  Lakes, for example, might show little impact from nutrient pollution until a threshold level is reached, and then massive algal blooms form that choke off many other species growth. In the absence of knowledge of exactly how far one can push a system before reaching a tipping point, many invoke the precautionary principle, which states that in the face of uncertainty, one should take the most conservative approach.

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In SEED Magazine, theoretical biologist George Sugihara writes about early warning signals for collapses in complex systems: A key phenomenon known for decades is so-called “critical slowing” as a threshold approaches. That is, a system’s dynamic response to external perturbations becomes more sluggish near tipping points. Mathematically, this property gives rise to increased inertia in the ups and downs of things like temperature or population numbers—we call this inertia “autocorrelation”—which in turn can result in larger swings, or more volatility.

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I have an article up at GOOD magazine about the abandoned rural lands and how to manage them for ecosystem services: Brazil has had a declining rural population since 1990. Even as loggers and farmers cut and burn ancient rainforest in the south, emigrants leave northern farmlands fallow. In China, between just 2000 and 2008, the countryside lost 86 million people. The United Nations projects that the world’s total rural population will begin to decline in the 2020s.

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