Earth has experienced five mass extinction events in its 4.5-billion-year history. The most recent — the asteroid impact that ended the Cretaceous period 66 million years ago — annihilated approximately 75% of all species, including the dinosaurs that had dominated terrestrial ecosystems for 165 million years.
We are now living through the sixth.
This time, the asteroid is us.
Species are currently disappearing at 100 to 1,000 times the natural background extinction rate. The background rate — the normal pace of species loss through evolutionary turnover — is approximately one to five species per year. Current estimates suggest we are losing species at a rate of dozens per day. Many vanish before they are even catalogued. They disappear unnamed, unmourned, their ecological roles unfilled, their genetic libraries burned before they are read.
The Living Planet Report — published by the World Wildlife Fund and the Zoological Society of London — has documented an average decline of 69% in monitored wildlife populations between 1970 and 2018. Not 69% of species gone. Sixty-nine percent of the individuals within monitored vertebrate populations — mammals, birds, fish, reptiles, amphibians — eliminated in less than fifty years.
This is not a gradual decline. It is a collapse.
The insect apocalypse may prove to be the most consequential ecological catastrophe of all — precisely because it is the least visible.
In 2017, researchers in Germany published a study that sent shockwaves through the scientific community. Using standardized insect traps in 63 protected nature reserves — not agricultural land, protected reserves — they documented a 75% decline in flying insect biomass over 27 years.
Three-quarters of the insects. Gone. From protected areas.
This was not an isolated finding. Studies from Puerto Rico's Luquillo rainforest documented a 78% decline in ground-dwelling arthropods and a 98% decline in canopy-dwelling arthropods over 36 years — accompanied by parallel declines in the birds, frogs, and lizards that depend on them for food. Similar patterns have been documented across Europe, Asia, and the Americas.
Insects are not optional. They are the foundation of terrestrial life. They pollinate the vast majority of flowering plants. They decompose organic matter, recycling nutrients back into the soil. They aerate the earth. They feed birds, bats, fish, amphibians, and reptiles. They regulate pest populations. They are the base of the food web upon which nearly every terrestrial ecosystem depends.
When the insects go, everything above them in the web follows. Not immediately. Not all at once. But inevitably. The birds that eat them decline. The plants they pollinate fail to reproduce. The soil they help build loses its fertility. The cascading effects ripple upward and outward through every connected system.
The pollinator crisis is the most immediately consequential dimension of insect decline for human civilization.
Approximately 75% of the world's food crops depend to some degree on animal pollination — primarily by bees, but also by butterflies, moths, beetles, flies, birds, and bats. Without pollinators, the production of fruits, vegetables, nuts, seeds, and oils collapses. What remains — wind-pollinated grains like wheat, rice, and corn — can sustain caloric survival but not nutritional health.
Honeybee colonies in the United States have declined from approximately 6 million in 1947 to roughly 2.5 million today. Colony collapse disorder — a phenomenon in which worker bees abandon their hive, leaving the queen and brood to die — emerged as a recognized crisis in the mid-2000s. But the decline had been underway for decades, driven by the convergence of multiple stressors.
Neonicotinoid pesticides — the most widely used insecticides in the world — are systemic: they are absorbed into every tissue of the treated plant, including pollen and nectar. Bees that forage on treated crops ingest the pesticide continuously at sub-lethal doses. These doses do not kill the bees immediately. They disorient them. They impair their navigation, their memory, their ability to communicate the location of food sources to their hive. They suppress their immune systems, making them vulnerable to parasites and disease. The bees do not die dramatically. They simply fail to find their way home.
The parallel to human civilization is difficult to ignore.
The oceans — which cover 71% of Earth's surface and produce more than half of the planet's oxygen — are undergoing transformations that threaten the marine food web from its foundation.
The ocean has absorbed approximately 30% of all human-generated CO2 since the industrial revolution. This absorption has prevented even more atmospheric warming, but at a devastating cost: the CO2 reacts with seawater to form carbonic acid, increasing ocean acidity by approximately 26% since the preindustrial era. This process — ocean acidification — is sometimes called "the other CO2 problem."
Acidification dissolves calcium carbonate — the compound that corals, shellfish, sea urchins, and certain plankton use to build their shells and skeletons. As acidity increases, these organisms struggle to form their protective structures. Some dissolve faster than they can grow.
Coral reefs are the rainforests of the sea. They occupy less than 1% of the ocean floor but support approximately 25% of all marine species. They provide nursery habitat for commercially important fish. They protect coastlines from storm surge. They sustain the livelihoods of approximately 500 million people worldwide.
They are dying. Mass bleaching events — triggered when ocean temperatures exceed the thermal tolerance of the symbiotic algae that give corals their color and energy — have become increasingly frequent and severe. The Great Barrier Reef has experienced five mass bleaching events since 2016. Scientists estimate that the world has already lost approximately 50% of its coral reef cover since 1950, and that under current trajectories, 90% could be gone by mid-century.
The freshwater crisis may be the constraint that hits hardest, soonest, and most irreversibly.
Aquifers — underground reservoirs of freshwater that accumulated over thousands to millions of years — are being pumped dry in decades. The Ogallala Aquifer beneath the Great Plains of the United States — one of the largest underground freshwater reserves on Earth — irrigates approximately 30% of all US crops. In parts of Kansas, Texas, and the Oklahoma panhandle, the aquifer has declined by more than 150 feet. At current extraction rates, significant portions will be functionally exhausted within a single generation.
The Ogallala is not unique. Aquifers beneath the North China Plain, the Indo-Gangetic Basin, the Arabian Peninsula, and North Africa are all being depleted far faster than they can be recharged. Globally, more than 2 billion people live in countries experiencing high water stress. By 2050, projections suggest that number could reach 5 billion.
Water is not substitutable. There is no alternative input. When the water is gone, the agriculture that depends on it ends. The cities that depend on it empty. The civilizations that depend on it collapse. This is not theoretical. It has happened before. The great civilizations of Mesopotamia, the Indus Valley, and the American Southwest all collapsed in part because they depleted the water systems that sustained them.
We are doing it again. Faster. At larger scale. With more people dependent on the systems being destroyed.
In 2009, a team of scientists led by Johan Rockstrom at the Stockholm Resilience Centre identified nine planetary boundaries — biophysical thresholds that define the safe operating space for human civilization on Earth. These boundaries include climate change, biodiversity loss, land-system change, freshwater use, ocean acidification, atmospheric aerosol loading, stratospheric ozone depletion, biogeochemical flows (nitrogen and phosphorus cycles), and the introduction of novel entities (synthetic chemicals and materials).
As of the most recent assessment in 2023, six of the nine boundaries have been crossed.
This is not a future projection. It is a present-tense diagnosis. Humanity is not approaching the limits of the planetary system that sustains it. Humanity has already exceeded them — in biodiversity, in climate, in land use, in biogeochemical flows, in freshwater, and in novel chemical contamination.
The metaphor is a river approaching a waterfall. Once the current reaches a certain speed, once the canoe passes a certain point, the outcome is no longer a matter of choice. It is a matter of physics.
The creatures that are disappearing — the insects, the amphibians, the coral, the birds — are not decorative features of a world designed for human use. They are the functional organs of the Living System that makes human life possible. Each species removed is a thread pulled from a tapestry. Remove enough threads and the tapestry does not gradually thin. It collapses — suddenly, catastrophically, and irreversibly on any timescale meaningful to human civilization.
As you do unto the least of these, you do unto Me.
What we do to the insects, the coral, the soil, and the water, we do to our children and to our Selves. We are not separate from nature. We are nature, awakening to what we have done.
The web of life is not something out there, surrounding us.
It is something in here, constituting us.
And it is unraveling.
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