fredag 14 oktober 2011

Dödar plast HUNDRATUSEN havsdäggdjur per år?

Harold Johnson går hos Scientific American till grunden med den vida angivna uppgiften att plast dödar 100 000 havsdäggdjur per år - ur texten: 

For one thing, many sources recycle the same “facts” over and over. One in particular keeps cropping up, on personal blogs, nonprofit Web sites, popular scientific eZines, press releases. The words change, but the gist is always this: “100,000 sea mammals are killed by marine plastic pollution every year.”

Wow. This is a striking number. Horrifying even.

Yet something has always bothered me about that number. It’s too round. Too easy. Too “everywhere.” The vanilla ice cream of heartstring-tugging environmentalism.

Och resultatet av efterforskningen (Johnsons länk och fetstil):

That workshop’s proceedings are available in full (pdf) on NOAA’s Marine Debris Web site. The figures for entanglement & death are on p. 269 of the report, but nowhere is the “100,000″ figure given.

The New York Times article of December 1984 is the first published record of the 100,000 number.

And just like that, I had the answer. A “fact” handed down & bandied about from article to nonprofit, conservation society to international organization, over years and years. So long that it has taken a life of its own, and becomes unquestioned, and unsourced. Whether there is — or was — any science behind it remains in doubt.

But seeking good science misses the point. The point is, the number is now 27 years old! If it ever had real value, it doesn’t now. The world is changed. But in an age of page hits, search engine optimization, and a crowded Web, it’s a number that’s just too good to pass up. Especially when it’s been “vetted” by heavyweights like National Geographic and the United Nations. It’s an excellent warning to us all. Sometimes “facts” are built on ether.

Paralleller dras lämpligtvis till exempelvis Mattias Svenssons kontroll av Folkhälsoinstitutets 385 000 barn i alkoholriskbrukande hushåll, där "riskbruk" visade sig anses motsvara mer än sex öl per vecka, och dessutom att barnen enligt den refererade studien inte tog skada ens då föräldrarna räknades till den betydligt tyngre kategorin "allvarliga alkoholproblem". Svensson visar också att den tidigare siffran om "200 000 barn i missbrukarfamiljer" baserades på en intervjuundersökning från Dalby, utförd 1957 och uppföljd 1972.


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