First come the plants: the Baishan fir and the Qiaojia pine, the coral tree and the suicide palm. Then come the insects, the Franklin’s bumblebee and the Bozdagh grasshopper in turn, then the spiders, the fish, the reptiles, the amphibians, the frogs, 17 kinds in all. Birds fly behind, finches and macaws and vultures and larks, monarchs and thrushes and curlews and crows. Last are the mammals, from the mightiest Javan rhinoceros to the meekest mountain pygmy possum.The Latin binomials of 192 endangered species make up the incantatory text of “Litanies of the Sixth Extinction,” the grim, dark heart of “Vespers of the Blessed Earth,” a new, 50-minute work by John Luther Adams that the Philadelphia Orchestra, the Crossing and the soprano Meigui Zhang will premiere under Yannick Nézet-Séguin in Philadelphia on Thursday, before taking it to Carnegie Hall on Friday.That’s 192 endangered species until low male voices invoke one more, the species that named the others and now threatens them, and itself, with extinction: Homo sapiens.“We’ve got to face that the situation is dire and it’s going to get worse before it gets better,” Adams said of the climate crisis, and his latest musical response to it, in a recent video interview from his home in the New Mexico desert. “The only way it’s going to get better is if we face the harsh, stark, sobering, actually terrifying realities ahead of us — and act on them.”Coincidentally, though tellingly, the “Vespers” will have their premiere little more than a week after the Intergovernmental Panel on Climate Change concluded in its latest report that “there is a rapidly closing window of opportunity to secure a livable and sustainable future for all.”For Matías Tarnopolsky, the president and chief executive of the Philadelphia Orchestra, the new “Vespers” are an example of the role that classical music can play in society.“We all believe that music can change the world,” Tarnopolsky said of the premiere’s creators, “that music can change the way we look at searing issues facing humanity. John Luther Adams’s music — his philosophy, his ethos — encapsulates that in all of his work.”Still, for all the ecological concern that has informed so much of what Adams has composed since he turned away from professional environmentalism several decades ago, he has rarely, if ever, been so direct as in these “Vespers.” Habitual disclaimers that his music and his activism were to some extent distinct used to surround works like “Become Ocean,” the consuming masterpiece that won him the Pulitzer Prize for music in 2014, and “Become Desert,” a New York Philharmonic co-commission that will have its belated Lincoln Center premiere this June.Following the example of Greta Thunberg, Adams took the train to Philadelphia from New Mexico, rather than fly.Aaron Richter for The New York Times“I believe that music has the power to inspire a renewal of human consciousness, culture, and politics,” Adams wrote in “Silences So Deep,” an eloquent memoir published in 2020. “And yet I refuse to make political art.”But the “Vespers” are markedly more urgent in tone compared with Adams’s typical “passive activism,” as it was called by Donald Nally, the conductor of the Crossing, which has recorded Adams works including “Canticles of the Holy Winds” and “Sila: The Breath of the World.”“He builds these sound worlds that allow you to appreciate the awesomeness, literally, of the world around us, even though you’re sitting in a concert hall that is probably contributing to the problem,” Nally said, pointing as an example to the first of the five vespers, “A Brief Descent Into Deep Time,” which sinks through the layered rocks of the Grand Canyon, eons of geology evoking the permanence of the Earth.“Music for me is a kind of spiritual discipline; it’s as close to religion as I get,” Adams said. “It’s a way of being in touch with mysteries larger, deeper, older than I can fathom, and so, because of that, I’ve never really been interested in expressing myself in music.”That changed, he continued, as he worked on the Philadelphia commission from spring 2020 on, amid superstorms, floods, police killings and the pandemic. His best friend, the nature writer Barry Lopez, died of prostate cancer that December, three months after a wildfire had burned parts of his home near the McKenzie River in Oregon, making him a climate refugee.“In the middle of all this,” Adams recalled, “I found myself composing what is if not the most personal, at least the most overtly expressive music I’ve ever composed.”But the “Vespers” are prayers, not a requiem. Even if Adams said that this score is one of the saddest and most austere that he has composed, it still celebrates the splendor of the enduring Earth, and is more melodic than some of his music has been. “If ‘Ocean’ and ‘Desert’ are Brucknerian,” he suggested, “this is almost Mozartean.”That dynamic of beauty and grief going hand in hand is especially apparent in “Night Shining Clouds,” a movement for strings alone that depicts cloud structures whose chemistry means that they are “getting more beautiful because we’re polluting the Earth more,” Adams said. It’s also clear in “Aria of the Ghost Bird,” the desolate final movement, a setting for soprano of the unrequited mating call of the last Kauai oo, a bird native to Hawaii that has not been heard since the 1980s.“It’s the song of an extinct bird, and yet it’s so beautiful,” Adams said. “One of my friends looked at the score and said, ‘Well, you just can’t help yourself, can you J.L.A., you have to end on a hopeful note.’ I said, ‘Jim, the bird’s extinct.’”Adams has not lost hope yet, though he admits that “the odds don’t look good for us as a species, and regardless even the best-case scenario isn’t very rosy.” The Biden administration’s recent decision to approve further oil drilling in his beloved Alaska is “kind of unbelievable,” he said.What gives Adams succor, even now, is a younger group of activists coming to the fore and working in new ways. Following the example of Greta Thunberg, he has cut back on travel and become more deliberate about his choices when it is unavoidable. To attend the back-to-back premieres of “Vespers” and “Night” — his part in “Proximity,” the triptych that opened last week at Lyric Opera of Chicago — he took the train from Albuquerque, rather than fly.“It’s these next generations that are going to have to sort through the rubble that my generation is leaving to them,” Adams said, “and imagine new ways of living together with one another, and living within the limits of biology — or our goose is cooked. But I’m not betting against them, in the face of all of it.”What role does that leave for an old-time environmentalist, now 70, writing music as the catastrophe that he long worked to avoid gathers speed?Adams often talked with Lopez, he said, about what it meant to be a “senior artist.” They agreed that they were, and could be, nothing like the elders of the Indigenous communities they knew. But when Adams recently reread “Arctic Dreams,” which won Lopez the National Book Award in 1986, he found a passage that reminded him of another ideal they had discussed.“The Inuit have a particular kind of person, an isumataq,” Adams said. “An isumataq is not an elder; an isumataq is a person who creates the atmosphere, or the place, within which wisdom may reveal itself. I think Barry was absolutely an isumataq. And that’s what I’m looking for in my own work, and have been looking for all my life. It’s not because I think I know anything. I don’t. I’m probably more clueless than the next person. It’s precisely because I don’t know, that I do what I do.”“I’m not trying to save you, or anyone else, let alone the world,” Adams continued. “First and foremost, I’m doing this because I’m lost, and I’m looking for religion. I’m looking for God, in that sense.” More