I remember, some years ago, the news headlines of an impending insect mass extinction. But I similarly remember pushback against the term “insect apocalypse”. When the publisher Jonathan Cape announced that well-known entomologist Dave Goulson was working on Silent Earth, my interest was naturally piqued. So, how bad is it, really?
Silent Earth is a well-written and logically structured book, neatly divided into five parts and 21 chapters, none of which run on for too long. After four earlier books published with Jonathan Cape nothing less was to be expected. Goulson first gives you his reasons for why he thinks insects matter, which are a mixture of both instrumental and intrinsic values. He candidly admits that “For me, the economic value of insects is just a tool with which to bash politicians over the head” (p. 37), while his reasons for caring about insects are primarily moral. Goulson then examines the evidence for insect declines, discusses potential causes, and outlines what can be done. His pen is sharp and he is not afraid to lash out in places, but I also found his writing infused with intellectual honesty and a willingness to consider criticism.
The part I was most interested in was chapter 4, which examines the evidence for insect declines. This is also, I expect, the part over which critics might take both this book and the whole argument to court. See, the problem is that, where insects are concerned, our data are woefully incomplete; something Goulson, to his credit, makes no secret of. His discussion of the relevant studies takes up a mere 20 pages and includes the 2017 Krefeld study that got the ball rolling, but was limited to reporting declining insect biomass in German nature reserves. A follow-up study by Seibold and colleagues was more thorough and reported similar declines. Other studies discussed here focus on particular insect taxa, though I found no mention of Reichholf’s work on butterflies. Unfortunately, there are few long-term studies available from elsewhere, but where we have looked, evidence predominantly points towards declines. An initial compilation of studies by Sánchez-Bayo and Wyckhuys was limited to those reporting declines, though a follow-up study by Van Klink and colleagues corrected for this and found a decline in terrestrial insects but an increase in freshwater insects, while highlighting that we have virtually no long-term data for Africa, South America, Oceania, and Asia. And keep in mind, Goulson adds, that the majority of insects have yet to be described, with (insect) taxonomists themselves a species in decline.
“where insects are concerned, our data are woefully incomplete; something Goulson […] makes no secret of. […] but where we have looked, evidence predominantly points towards declines.”
Given these huge gaps in our knowledge, are biblical phrases such as “insect apocalypse” justified? This has been much discussed and there are two contributions worth highlighting. Ed Yong wrote an excellent piece for The Atlantic in 2019, pointing out that headlines of total insect extinction in X years are absurd (Goulson also calls this “an unlikely claim” [p. 64]), and hits the nail on the head by reminding us that this question “goes beyond the fate of insects: How do we preserve our rapidly changing world when the unknowns are vast and the cost of inaction is potentially high?” Do we wait and gather more data, or, with the precautionary principle in mind, act now? Then, just this June, the British Ecological Society put up a panel debate on YouTube whose take-home message effectively was “be worried, but don’t believe the hype”.
Because make no mistake, there are good reasons to be very concerned. After a brief but powerful reminder of the very relevant phenomenon of shifting baselines, Goulson spends most of Silent Earth reviewing the many environmental insults we hurl at insects and other wildlife. This covers habitat loss and fragmentation, pesticides, herbicides, industrial agricultural practices, the spread of insect parasites and diseases by humans, climate change, light pollution (only little studied), and invasive species. Just some of the interesting and worrying findings are that habitat fragmentation is likely to interfere with insects relocating in response to climate change, and that certain mixtures of pesticides can have unexpectedly harmful interactions. Above all, Goulson points out, these threats are often studied in isolation but act in concert. Is it any surprise if insects are declining?
“Given [the] huge gaps in our knowledge, are biblical phrases such as “insect apocalypse” justified? This has been much discussed […]”
What stood out throughout this part of the book is Goulson’s intellectual honesty: he is always willing to point out the shortcomings in studies. When discussing the controversial glyphosate debate—which has alternately been judged likely and not likely carcinogenic by major organisations—he remarks that even for a trained scientist “it is hard to know what to conclude” (p. 127) and that he is “not absolutely certain where the truth lies” (p. 132–33). Goulson shows a remarkable willingness to remain open-minded but will call bullshit where he sees it. Chemtrail conspiracy theorists “are generally dismissed as crackpots, and rightly so” (p. 193), but geo-engineering is risky. There is no link between 5G and COVID-19 but “just because some people are crazy does not mean that 5G has no consequences for the health of people or wildlife” (p. 197). Biodynamic farming is largely harmless, but “[…] there are aspects to [it] that are beyond the boundaries of conventional science” (p. 269). And though he recognises that genetic modification of crops could reduce the need for pesticides, the technology is now predominantly wielded by the wrong people—the only sensible opposition to GMOs in my opinion.
There was one unfortunate tendency noticeable in these chapters: Goulson’s Further Reading section is not always complete—especially the pesticide chapter sometimes misses relevant studies discussed in the text (e.g. on p. 106 Goulson mentions a study by Sur & Stork that is not listed). And because he neither clearly references all of them, nor uses footnotes, it is not always immediately apparent what study he discusses. I am familiar with the argument that in books for a general audience you do not want to constantly interrupt the flow of your narrative with citations, which is why I prefer superscripts leading to numbered endnotes. Though most can be identified with some effort, readers should not have to repeat Goulson’s research, especially on controversial topics where the data matters.
“[…] there are good reasons to be very concerned […] the many environmental insults we hurl at insects and other wildlife […] are often studied in isolation but act […] in concert.”
A valuable side to Silent Earth is that Goulson does not just raise the alarm, but also suggests solutions. There are tips for making gardens insect-friendly, but he focuses particularly on the far more pressing issue of overhauling agriculture, which takes up so much more land. Much of what he recommends here is sensible advice, whether or not insects are in dire or not-so-dire straits. Yet I feel he only intimates, rather than calls out, that this requires affluent Westerners to redefine what makes a good life and embrace an ethos of self-limitation. Meanwhile, addressing climate change gets the barest of mentions. And though he repeatedly points out our soon-to-be world population of an estimated 10 billion, the word overpopulation never crosses his lips. I guess it would be unreasonable of me to expect one man to have all the answers.
Silent Earth is an incredibly important book that raises the alarm on a topic that needs far more attention but also left me feeling terribly conflicted. Our data on insect decline are very patchy, yet our impact on the natural world documented here is undeniable, leaving us in a diabolical bind: gathering more data takes time, yet without it, few people might be convinced that adopting precautionary measures is the sensible course of action. I am similarly torn over the phrase “insect apocalypse” on the cover, especially as the contents of this book are alarming but not alarmist. As mentioned in my review of The Uninhabitable Earth, such phrases draw attention but risk backfiring: if people perceive it to be hyperbole there is the risk they check out prematurely of a problem that does need our urgent attention, while vested interests will happily exploit it to undermine your credibility. I hope this does not happen, as we do need a far wider recognition that insects keep the world ticking over. And since they can quickly recover, all is not lost. Lastly, it will be interesting to see what tack the upcoming The Insect Crisis will take and whether it can contribute anything Goulson has not already covered.
Disclosure: The publisher provided a review copy of this book. The opinion expressed here is my own, however.
Other recommended books mentioned in this review: