In just 40 years, the world’s vertebrate wildlife populations have declined 60 percent, according to a new report by the World Wildlife Fund.

This sobering study doesn’t surprise me. I’ve watched nonhuman vertebrates (all mammals, birds, reptiles, amphibians and fish) decline my whole life.

The study, WWF’s biennial Living Planet Report, which surveyed data from 16,700 populations of more than 4,000 species, found the global rate of species loss is 100 to 1,000 times higher than a few centuries ago.

The planet is experiencing its sixth mass extinction, the first one in human history — and it’s caused by us.

The primary cause of the decline is habitat loss and degradation, which accounts for nearly half of all threats within each taxonomic group, except fish (28 percent).

Humans destroy and degrade habitat through “unsustainable agriculture, logging, transportation, residential or commercial development, energy production and mining,” the report notes, adding “fragmentation of rivers and streams and abstraction of water” are the main threats in freshwater ecosystems.

Roughly 20 percent of the Amazon rainforest has disappeared in just 50 years, while about half of all shallow-water corals have been lost in the last 30 years. Wetlands have shrunk by 87 percent in the modern era, according to the report.

The second cause of this decline is overexploitation, which refers not only to deliberate hunting, poaching and harvesting of wildlife, but also to the unintentional killing of non-target species, commonly known as bycatch. This is a particularly big problem for fish, accounting for 55 percent of loss in their populations.

Other top threats include invasive species, disease, pollution and climate change. Climate change accounts for 12 percent of bird and 8 percent of fish declines, the report states.

The fastest wildlife decline is in freshwater habitats, which lost 83 percent of their vertebrate populations between 1970 and 2014. The total number of freshwater vertebrates drops by about 4 percent each year.

The planet’s tropical regions are losing vertebrate species at an especially dramatic rate, with South and Central America suffering an 89 percent decline.

Biodiversity is not a luxury that’s “nice to have,” as the report puts it, but the foundation of human civilization. Globally, these ecosystem services are worth an estimated $125 trillion per year.

As one example, the report examines how much we rely on the planet’s pollinators — which are responsible for $235 billion to $577 billion in crop production per year — and how their abundance, diversity and health are affected by climate change, intensive agriculture, invasive species and emerging diseases.

As I have noted before, as the human population pushes toward 8 billion, we must slow our growth to preserve and restore the planet to a healthy equilibrium.

Biologist E.O. Wilson has proposed saving half the Earth for other species. To do so, we must reduce our agricultural footprint, especially meat production, and our desire for ever-larger cars, houses and shopping malls.

The clock is ticking and once-abundant life forms are disappearing. Are you willing to change your footprint to save them?

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