Wednesday, October 31, 2012

How the oceans might collapse

Here is yet another refutation of the denialist assertion that all the world needs is more growth.  There is hope for the oceans, but only if catches are reduced to levels substantially below present catches, and substantially below so-called maximum sustainable yields (MSY).

From ScienceVol. 338 no. 6106 pp. 474-475

The Risks of Overfishing

On page 517 of this issue, Costello et al. paint a dismal picture of the state of the world's fisheries. The authors report that globally, the vast majority of exploited fish populations have been depleted to abundance levels well below those recommended by conventional management guidance. Of even greater concern, most species are on a continuing trajectory of decline. These insights were gleaned from analyses of data from previously unassessed fish populations. These poorly understood fisheries, which represent about 80% of the world's fish catch, are in much worse shape than the relatively well-studied fisheries on which previous global status reviews have relied...

On the basis of these and other observations, the Lenfest Forage Fish Task Force recommended that catches of many forage fish species be cut in half relative to conventional guidance, and that no new forage fish fisheries should be instituted in low-information circumstances.

Dayton argued for a shift in the burden of proof for fisheries management decisions, in line with that applied in other natural resource and human health and safety policy arenas. This shift in the burden of proof would require demonstration of no serious impact before fishing could proceed. It is justified not least because the risks of continuing fishing when it results in serious negative consequences are generally much greater than the risks of curtailing fishing when it does not have a deleterious impact.


Sunday, October 28, 2012

The Limits to Growth, and Thinking in Systems

 I've just responded to a typical denialist dismissal of The Limits to Growth: The 30-Year Update

The short summary:

1. The authors of the limits to growth computer models are much more nuanced and critical of their models than are their detractors.

2. The book, Thinking in Systems: A Primer, discusses the fundamental aspects of the model, and how such models change our view of the world.  If there is one book that I wish everyone would read, including every scientist, politician, business leader and educator, it would be Thinking in Systems: A Primer.