Monday, August 8, 2011

And you thought Moody's downgrade of US Bonds was bad...

In Walter Miller's post-apocalyptic sci-fi classic "A Canticle for Leibowitz," one after-effect of the nuclear holocaust is euphemistically called "the Simplification." Most sentient earthlings who pay attention to such things are aware that there is an ecological holocaust in progress. It's been going on since we got handy with spears, but the pace has really picked up in the last century as we've gotten handy with organic chemicals and with bulldozers. As with Miller's (thankfully fictional) holocaust, there is also a simplification.

A good candidate for "most depressing title of a journal article" would be a report from UC Santa Cruz entitled "Trophic Downgrading of Planet Earth." These cheery six pages illustrate how, in just about every habitat, there used to be a much more complicated food chain (or "trophic web," as is the preferred term) and a richer, more diverse, more ecologically and economically useful biota. In just about every habitat, deliberate or inadvertent human activity has removed a "top predator" from the habitat, resulting in a much simpler ecosystem--and one that is less ecologically and economically useful.

The "top predators" in each ecosystem don't just skim the cream off the ecosystem, they are essential to maintaining its complexity. Unfortunately, top predators are also the most desirable as trophies, the most sensitive to habitat loss, and the most efficient at bioaccumulating toxins. When these species collapse, a complicated, interconnected trophic web abruptly telescopes into a short, simple food chain--often one that favors weeds or invasive species. As the authors put it, "the transitions in ecosystems that characterize such changes are often abrupt...difficult to reverse, and commonly lead to radically different patterns and pathways of energy an material flux and sequestration."

The authors of this paper provide example after example, from every habitat. For instance, it may be hard to see the causal link between eliminating lions and catastrophic fires, but it's there:

No lions-->more cattle-->rinderpest-->no herbivory-->grassland replacement by trees-->fire.

This isn't bunk; in one of the rare cases of good news, rinderpest (a cattle plague) has been declared extinct as the result of a coordinated international effort. There's a direct correlation between disappearance of rinderpest and reestablishment of grassland.

But really, most of the news is bad, in just about every habitat. It takes an extremely willful blindness to just go along as if everything is OK and the environment doesn't need some sort of protection.

You can make your own conclusions about various politicians here. In Miller's book, the people who drove The Simplification--burning libraries, killing scientists and engineers, and destroying machines--were called "simpletons," an appellation they wore with pride. There are certainly many politicians who like things very simple. Maybe these real-life simpletons are happy that we are experiencing a planet-wide simplification.

James A. Estes et al (2011). Trophic Downgrading of Planet Earth. Science 333:301-306.
Miller, Walter M. (1959). A Canticle for Leibowitz. J. B. Lippincott & Co, Philadelphia.

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