One study on a German nature reserve found insect biomass (e.g., kilograms of insects you’d catch in a net) has declined 75% over the last 27 years. Here’s a good summary that answered some questions I had about the study itself.
Another review study found that, globally, invertebrate (mostly insect) abundance has declined 35% over the last 40 years.
Why aren’t we all dead yet?
This is an honest question, and I want an answer. (Readers will know I take catastrophic possibilities very seriously.) Insects are among the most numerous animals on earth and central to our ecosystems, food chains, etcetera. 35%+ lower populations are the kind of thing where, if you’d asked me to guess the result in advanced, I would have expected marked effects on ecosystems. By 75% declines – if the German study reflects the rest of the world to any degree – I would have predicted literal global catastrophe.
So what’s the deal? Any ideas?
Speculation/answers welcome in the comments. Try to convey how confident you are and what your sources are, if you refer to any.
(If your answer is “the biosphere has exploded already”, can you explain how, and why that hasn’t changed trends in things like global crop production or human population growth? I believe, and think most other readers will agree, that various parts of ecosystems worldwide are obviously being degraded, but not to the degree that I would expect by drastic global declines in insect numbers (especially compared to other well-understood factors like carbon dioxide emissions or deforestation.) If you have reason to think otherwise, let me know.)
Sidenote: I was going to append this with a similar question about the decline in ocean phytoplankton levels I’d heard about – the news that populations of phytoplankton, the little guys that feed the ocean food chain and make most of the oxygen on earth, have decreased 40% since 1950.
But a better dataset, collected over 80 years with consistent methods, suggests that phytoplankton have actually increased over time. There’s speculation that the appearance of decrease in the other study may have been because they switched measurement methods partway through. An apocalypse for another day! Or hopefully, no other day, ever.
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