Emma Marris writes:

When the last of four dams on the Klamath River in southern Oregon and Northern California was demolished in October 2024, everyone who knew the river well had a question: How long would it take for salmon to reclaim the upper reaches they’d been cut off from for more than 100 years?

About 10 months later, when they began their fall migration, Chinook salmon immediately took advantage of their new river access, looking for places upstream to lay or fertilize eggs. But the fish still faced two intact dams and no one was sure if the salmon would make it through the fish ladders, structures designed for trout, a smaller species, to bypass the dams.

Then in September, a video camera caught them leaping up the ladders like pros.

William E. Ray Jr., chairman of the Klamath tribes, whose people used to rely on salmon for about a third of their diet, told me he was stunned to see the fish make it all the way to Upper Klamath Lake in Oregon in October. And they are back in the hundreds. Mark Hereford, an Oregon state fish biologist, told me he didn’t expect this magnitude of fish to return for a decade.

Salmon are tough, and they’re a reminder that although nature is sometimes very fragile, decades of conservation rhetoric have perhaps overstated that fragility. Nature can bounce back, often quickly.

From “The Lion King” to nature documentaries, we’re told that when you remove one part of a delicate ecosystem, the whole thing can come crashing down. There’s also the seemingly endless series of scientific reports about the decline of species, from frogs to birds, and the message that we are in the perilous, hopeless “sixth mass extinction” in which species are perishing at rates far above average.

The role of our leaders: Writing at the end of 2020, Al Gore, the 45th vice president of the United States, found reasons for optimism in the Biden presidency, a feeling perhaps borne out by the passing of major climate legislation. That doesn’t mean there haven’t been criticisms. For example, Charles Harvey and Kurt House argue that subsidies for climate capture technology will ultimately be a waste.

The worst climate risks, mapped: In this feature, select a country, and we’ll break down the climate hazards it faces. In the case of America, our maps, developed with experts, show where extreme heat is causing the most deaths.

What people can do: Justin Gillis and Hal Harvey describe the types of local activism that might be needed, while Saul Griffith points to how Australia shows the way on rooftop solar. Meanwhile, small changes at the office might be one good way to cut significant emissions, writes Carlos Gamarra.

Though the extinction rate for the past few hundred years has indeed been far higher than the average, out of some 1.8 million described species, humans have been the primary cause of fewer than 1,000 known extinctions since the year 1500. Claiming we are already in the sixth mass extinction event suggests that the threatened species are already doomed and there’s no possibility for them to recover.

Some species do require extreme measures to be saved, like the kākāpō, a charming green flightless parrot from New Zealand that can survive only on islands that wildlife managers keep free of predators. And for the roughly 16 percent of threatened species whose central menace is climate change, it’s a complex, global fight.

But many species and ecosystems can rebound even when we take relatively simple actions to protect them: Look no further than the bison, elephants, humpback whales, egrets, bald eagles and many others that have shown that recovery is possible. [Continue reading…]