Conservation

The Sixth Extinction

Background extinction rate is ~1 species per million per year. Current rate runs 100–1,000 times faster.

Earth is in the early phase of its sixth mass extinction. The previous five were caused by asteroid impacts, supervolcanic eruptions, oceanic anoxia. This one is caused by us — by habitat loss, hunting, invasive species, pollution, and climate change. Conservation is the science and practice of slowing it.

Elizabeth Kolbert's 2014 book of that title made the case to a general readership. The job of biologists is now triage: identify what is salvageable, prioritize hot-spots, document what cannot be saved.

The Catalogue of Life and Death

157,000 species assessed. 42,100 threatened. The Red List is the world's authoritative inventory of extinction risk.

Categories: EX (Extinct), EW (Extinct in the Wild), CR (Critically Endangered), EN (Endangered), VU (Vulnerable), NT (Near Threatened), LC (Least Concern), DD (Data Deficient).

Protected Areas of the World

As of 2024: 17% of land and 8% of marine area under formal protection. Goal of 30x30 (30% by 2030) adopted at CBD COP-15, Montréal 2022.

The Wolves of Yellowstone

In 1926 the last wild gray wolf in Yellowstone was shot. The park's elk herd exploded — to ~17,000 — overgrazing willow and aspen along streambeds, eroding banks, displacing beavers and songbirds. In January 1995, ecologist Doug Smith led the reintroduction of 14 wolves from Alberta. Within a decade, beaver colonies tripled. Aspen returned. Songbirds, otter, even the geometry of the rivers shifted.

This "trophic cascade," documented by Bill Ripple and Robert Beschta, became the textbook case for top-predator restoration. Wolves now number ~108 inside the park.

The Return of the Bison

Hunted to extinction in the wild by 1927. Bred from 12 captive zoo individuals. Today: ~9,500 European bison across Poland, Belarus, Romania, Spain.

The European bison (Bison bonasus) is now the largest land mammal on the continent. Białowieża Forest, on the Polish-Belarusian border, holds the largest free-ranging herd. Rewilding Europe coordinates ongoing reintroductions in the Carpathians, Iberia, the Velebit Mountains. Beavers, lynx, wolves, ibex, vultures — all returning to landscapes from which they were extirpated centuries ago.

Papahānaumokuākea

The largest contiguous protected area in the United States and one of the largest MPAs on Earth — 1.5 million km² of Pacific around the Northwestern Hawaiian Islands. Established by President George W. Bush in 2006, expanded by Obama in 2016. Home to monk seals, green sea turtles, 7,000+ marine species. No commercial fishing permitted.

Other model MPAs: Cabo Pulmo (Mexico) — biomass increased 460% in 10 years after no-take zone. Chagos Marine Reserve (640,000 km²). Phoenix Islands (Kiribati). Ross Sea (1.55 million km², 2017).

Frozen Arks & Seed Vaults

Conservationists in Their Own Words

"In the end, we will conserve only what we love. We will love only what we understand. We will understand only what we are taught." — Baba Dioum, Senegalese forester, 1968

"I do not want to die … until I have faithfully made the most of my talent." — Wangari Maathai, Nobel Peace Prize 2004

"The continued existence of wildlife and wilderness is important to the quality of life of humans." — Jim Fowler

What Worked

• Humpback whale — from ~5,000 in 1966 to ~135,000 today; delisted 2016.
• Bald eagle — 487 nesting pairs in 1963 (US lower 48) to ~71,400 today; DDT ban 1972.
• Iberian lynx — 94 individuals in 2002 to 1,668 in 2023; Portugal-Spain Iberlince program.
• Mountain gorilla — ~250 in 1981 to 1,063 in 2018; first great ape to move from CR to EN.
• Arabian oryx — extinct in wild 1972; reintroduced from captive stock; now ~1,200 wild.
• Peregrine falcon — <325 nesting pairs in N. America 1975 to ~3,000+ today.

Functionally Extinct

Some species are below the genetic and demographic thresholds for survival even with perfect management. The northern white rhino: two females remain (Najin and Fatu, Kenya), no males. IVF using cryopreserved semen and surrogate southern white rhinos is the only chance. The Yangtze giant softshell turtle: three individuals known. The vaquita: under ten.

Conservation has had to develop a category beyond "endangered" — "conservation-reliant." Some species will require permanent management.

The Long Game

Conservation is generational work. Yellowstone was set aside in 1872; its wolves came back in 1995. The 30x30 target points to 2030 — but the bison-Białowieża story took 100 years. The patience required is biblical. The rewards — a planet that still includes tigers, elephants, redwoods, coral, in 2125 — depend on choices made now.

"We have not inherited the Earth from our ancestors; we have borrowed it from our children." — Native American proverb (popularized by Lester Brown)