Unseen Decline: Exploring the Silent Extinction of Life on Earth
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… Because insects are legion, inconspicuous and hard to meaningfully track, the fear that there might be far fewer than before was more felt than documented, a feeling so common entomologists developed a shorthand for it - the windshield phenomenon… Humans are not great at remembering the past accurately. This is especially true when it comes to changes to the natural world… In decades of photos of fishermen holding up their catch in the Florida Keys, the marine biologist Loren McClenachan found a perfect illustration of this phenomenon, which is often called “shifting baseline syndrome.” The fish got smaller and smaller, to the point where the prize catches were dwarfed by fish that in years past were piled up and ignored. But the smiles on the fishermen’s faces stayed the same size…
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What we’re losing is not just the diversity part of biodiversity, but the bio part: life in sheer quantity. For example, the world’s largest king penguin colony shrank by 88 percent in 35 years, more than 97 percent of the bluefin tuna that once lived in the ocean are gone… Finding reassurance in the survival of a few symbolic standard-bearers ignores the value of abundance... Tigers still exist, for example, but 93 percent of the land where they used to live is now tigerless. Large animals, especially top predators like tigers, connect ecosystems to one another and move energy and resources among them simply by walking and eating and defecating and dying. In the deep ocean, sunken whale carcasses form the basis of entire ecosystems in nutrient-poor places. One result of their loss is what’s known as trophic cascade, the unravelling of an ecosystem’s fabric as prey populations boom and crash and the various levels of the food web no longer keep each other in check…
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Scientists speak of functional extinction, when animals and plants are present, but no longer prevalent enough to affect how an ecosystem works - the extinction not of a species but of all its former interactions with its environment, an extinction of seed dispersal and predation and pollination and all the other ecological functions an animal once had. The more interactions are lost, the more disordered the ecosystem becomes. A paper in Nature suggested that a loss of even 30 percent of a species’ abundance can be so destabilizing that other species start going fully, numerically extinct. A famous real-world example of this type of cascade concerns sea otters. When they were nearly wiped out in the northern Pacific, their prey, sea urchins, ballooned in number and [completely] decimated kelp forests, turning a rich environment into a barren one and also possibly contributing to numerical extinctions, notably of the Steller’s sea cow.
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… In addition to extinction (the complete loss of a species) and extirpation (a localized extinction), scientists now speak of defaunation: the loss of individuals, the loss of abundance, the loss of a place’s absolute animalness. It is estimated that, since 1970, Earth’s various populations of wild land animals have lost, on average, 60 percent of their members... If you look at the world’s mammals by weight, 96 percent of that biomass is humans and livestock. We talk about living in the Anthropocene, a world shaped by humans. But E.O. Wilson, the naturalist and prophet of environmental degradation, has suggested another name: the Eremocine, the age of loneliness.
