WE ALL HAVE OUR environmental nightmares. Mine feature jumbo squid.

A cross between an octopus (those flesh-grasping tentacles and big, Javier Bardem–like eyes) and an underwater parrot (beaks on sea creatures just seem wrong), these voracious predators are bullying their way into new turf faster than an army of methed-up street thugs.

It gives me the willies, the notion of our aquatic food chain being lorded over by ruthless cephalopods that scientists suspect are better suited to climate change than the creatures they'll displace.

If that doesn't bother you, consider novelist T. C. Boyle's vision of eco-Armageddon. The protagonist of A Friend of the Earth (Viking, 2000) lives circa 2025 in a compound much like Michael Jackson's Neverland. As the weather grows increasingly violent, he struggles to care for a handful of the planet's few remaining species. Here's what some will find really scary, though: In this future without biodiversity, our sushi choices will largely be limited to koi and catfish.

Given the apocalyptic stories we tell ourselves these days, is it any wonder that San Francisco magazine recently identified a new modern malady: eco-neurosis (see "Mixed Media")?

Sierra thinks the best therapy for environmental angst is knowledge followed by action. For example, Joan Hamilton's piece, "The Tortoise and the Hare," follows researchers seeking clues to two disparate species' prospects as their mountain and desert homes heat up.

Not long after Joan filed her story, her husband, Bruce Hamilton, the Sierra Club's deputy executive director, came by my office. Like Joan, Bruce fits my image of the classic Sierra Clubber. His bearded face has seen blistering deserts and wind-beaten peaks. His pale eyes hint that nature has imparted wisdom. These days they reveal a sadness. But there's a fiery joy too as he describes Building Resilient Habitats, a Club initiative that calls for a North American web of interconnected reserves--existing and yet to be created--that would allow animals to migrate to new ground before global warming does them in.

The doomsday visions sprouting in humanity's collective imagination include global sterility and surreal, survival-of-the-fittest realms inhabited solely by cockroaches, catfish, and new monsters of adaptability.

In the movie I Am Legend, Will Smith's character battles mutant species on a disease-crippled earth. In Cormac McCarthy's novel The Road (Random House, 2006), a father and son scratch their way across a landscape laid to utter waste.

Not to spoil these stories, but each ends on a measure of uplift. No matter how tough things get, the tales suggest, good people tend to find each other, pull together, start to fix things. We find such endings believable because ultimately--and despite evidence to the contrary--we humans have faith that we're smarter than squid.

Illustration by Dewey Saunders; used with permission.