The librarian was nondescript in the way that everyone standing behind a counter is, probably in her 30s, with straight, fox-colored hair. When she took my stack of books, I noticed the way her sweater draped over a conspicuous melon-shaped belly, and I felt a tug in my chest and warmth rise in my stomach. It took a moment to recognize this sensation as envy. Then came another feeling: shock. I had never been jealous of any woman for carrying what looked like an uncomfortable load, or for what would come next: the messy, exhausting job of mothering an infant. Something unfamiliar had come over me.

In my late 20s and early 30s, I was terrified of becoming the sort of woman who was “baby crazy,” afraid motherhood would circumscribe my life. I politely admired but didn’t gush over my friends’ new babies. Compared with many women, I was under little pressure to procreate; neither my nor my husband’s parents had ever expressed more than a tentative longing for grandchildren. But six years ago, when I first held my 2-month-old niece, wrapped in a flower-print onesie and murmuring delicious baby noises, I felt a rush of joy, an indescribable feeling of human closeness.

My husband and I had made a home in Seattle for several years, and my friends of childbearing age tended to be writers and activists, scientists and scholars. When considering kids, they weighed not only their desires and finances but the state of the world. Many of them had read grim prognoses of what climate change would do to life on Earth. Even in the restrained language of science, the future holds unprecedented difficulties and disasters. For many people, these problems were an abstraction, but as an environmental journalist, I knew enough to imagine them in front of me. Driving across the bridge to my house, I pictured city beaches drowned by the rising sea. Watching the news, I wondered when the next colossal hurricane would strike the Gulf of Mexico or the mid-Atlantic. These thoughts are not paranoid. According to scientists’ predictions, if society keeps pumping out carbon dioxide at current rates, any child born now could, by midlife, watch Superstorm Sandy–size disasters regularly inundate New York City. She could see the wheat fields of the Great Plains turn to dust and parts of California gripped by decades of drought. She may see world food prices soar and water in the American West become even scarcer. By 2050, when still in her 30s, she could witness global wars waged over food and land. “It does make me wonder if maybe I shouldn’t have kids,” one of my friends whispered to me. A year later, she was pregnant. What had changed her mind?

I heard a lot of stray comments like this as I sat on the fence between motherhood and childlessness. A male musician I knew wondered when I might have a baby, then mused that most people he knew thought the world was too screwed up for children. A literary agent who took me to lunch asked if my reporting on climate change left me so gloomy that I didn’t want to have kids at all.

Sometimes when I considered the question, the sadness nearly suffocated me. Still, in the months after I saw the librarian, some kind of maternal sensibility was switched on in my mind, and I tuned in to the presence of children the way a bird-watcher is alert to avian activity. Grinning girls with micro-braids on bikes, the kids who left popsicle-stick art strung from trees near my house, my friends’ photographs of their newborns on Facebook—they struck me with a plaintive ache. On a flight back from a conference, I gave my window seat to a bespectacled 10-year-old girl traveling alone. She looked so shy that I had an urge to find out where was she going and if she was safe, though I said nothing.

One evening I confided to a friend, as her 4-year-old son ran toy trucks through the adjacent room, that I thought about having a baby, but I worried how to keep a child safe in a future wracked by global warming. “I know,” she said, her face tightening with fear. “I don’t know what to do about it. I feel so helpless.” For a moment, we both were silent.

* * *

In 1970, the biologist Paul Ehrlich leaned over a podium at Northwestern University and declared, “The American woman of the year is the sterile woman who adopts two children.” It was the beginning of a half-century of ambivalence among environmentalists over the nature of motherhood. Two years before his Northwestern speech, Ehrlich and his wife, Anne, had unleashed the best seller The Population Bomb (though the publisher insisted on removing Anne’s name from the byline). The book popularized the notion that the world was headed for a population explosion with catastrophic consequences: Too many people and too few resources would mean horrifying famine and world wars.

The Ehrlichs were willing to entertain extreme solutions, such as “the addition of temporary sterilants to water supplies or staple food.” For some, their ideas conjured up America’s repugnant history of eugenics—in which medical authorities coerced thousands of men and women, especially women of color and the poor and disabled, to get surgically sterilized, a practice that began at the turn of the 20th century and continued through at least the 1970s. The Ehrlichs and other population-control advocates alienated a number of audiences of color—though Paul was also active in the civil-rights movement, and the couple has insisted that there was no racial bias in their case for population control. But at the dawn of the sexual revolution and the modern environmental movement, the book generated a groundswell of enthusiasm. With scientist Charles Remington and lawyer Richard Bowers, the Ehrlichs founded the organization Zero Population Growth; in just over a year, it grew to 102 chapters in 30 states. The popularity of these ideas helped stoke the public sentiment that led to the legalization of abortion. But the threat of overpopulation also became a cover for attacks on immigrants and the poor. Ellen Peck, founder of a 1970s anti-overpopulation group called the National Organization for Non-Parents, faulted government housing and welfare programs for bailing “irresponsible baby-breeders out of their partially self-created financial responsibilities.” As recently as 2004, white-supremacist and anti-immigration groups tried to vie for seats on the Sierra Club’s board in an effort to push the conservation group to oppose immigration to the United States.

Mothers carried moral heft in some environmental fights. Among the most iconic eco-heroes are women like Hazel Johnson, the mother of seven who, from the late 1970s through the 1990s, pushed city and federal officials to clean up asbestos and filter cyanide out of the tap water of some of Chicago’s mostly African-American neighborhoods. Lois Gibbs, mother of four, fought for the cleanup of Love Canal, a neighborhood in Niagara Falls, New York, built on a dumping ground for toxic chemicals. But today, having even one child can pose a moral quandary for some environmentalists. In a 2009 report, statisticians at Oregon State University determined that giving birth to one more American “adds about 9,441 metric tons of carbon dioxide to the carbon legacy of an average female.” Factoring in grandchildren and great-grandchildren, it multiplies her “lifetime emissions” by a factor of nearly six.

The OSU study is one of many recent attempts to quantify the environmental impact of parenthood. But it didn’t make sense, I thought, to filter the world’s most pressing environmental dilemma through the private choices of an individual woman. That analysis left out significant pieces of the puzzle. The average woman couldn’t, by herself, wrench billions of barrels of oil and tons of coal out of North American soil and sell them overseas, or stonewall policies that might have steered the US economy away from fossil fuels years ago.

* * *

Conceivable Future founder Meghan Kallman.(Steve Ahlquist)

As a child, Meghan Kallman used to announce: “I don’t want to have kids.” She wasn’t sure it was really true, but she relished the look of confusion that would appear on grown-ups’ faces. Now in her early 30s, Kallman is a doctoral student in sociology at Brown University. In the fall of 2014, she and a former Occupy activist named Josephine Ferorelli launched the Conceivable Future project, which seeks a more compassionate way to talk about the decision to have—or not have—children in an era marked by climate change. The project’s mission statement is a kind of manifesto: “The climate crisis is a reproductive crisis…. As we consider having families, it becomes clear that the perils of climate change have made this a terrifying time to make such choices…. We now have to worry that the planet won’t support our children.” So far, the project consists of living-room-style forums, more than a dozen events held to date in places like Chicago, Boston, Seattle, Salt Lake City, New York City, and rural New England. Each event offers men and women space to share their feelings on children and climate change in small groups, sometimes on camera for the video statements collected on the project’s website.

I first glimpsed Kallman last June in Seattle, playing trumpet in an activist ensemble called the Extraordinary Rendition Band and dressed in a performance get-up of frothy tulle skirt, white fedora with a gold scarf twirled around the brim, combat boots, and torn fishnet stockings. I watched as the band honked out a set that was mostly boisterous and loud at an urban park near an abandoned gas plant. But their last number was a somber Mexican funeral march, and in the middle of the tune, Kallman—who also teaches in Rhode Island’s state prisons—held up a megaphone and recited lines adapted from The New Jim Crow: “We have not done away with racial injustice in the United States. We have merely redesigned it.” “That’s the truth!” hollered a man in the audience, and the crowd shrieked with enthusiasm.

Conceivable Future’s logo.(Artwork: Josephine Ferorelli)

A few hours earlier, I’d been sitting with Kallman outside a bagel shop, both of us shivering in the chilly morning air. The daughter of a public-school teacher and a builder from rural New England, Kallman started attending protests when she was in college. In 2011, she was arrested in a Washington, DC, demonstration against the Keystone XL pipeline. She told me haltingly that she’d had an abortion two years before. “It would be disingenuous for me to say the whole reason I had an abortion was climate change,” she added. For one thing, she hadn’t yet found the right person to start a family with. “But there was also this lingering doubt about whether I feel like it’s fair to create new life in the face of this mess.”

In 2014, she met Tim DeChristopher, an activist who’d spent two years in prison for posing as a bidder to block the auction of drilling leases on public lands in Utah. On his release, he relocated to the Northeast, and the two had begun dating that summer. The following spring, they had moved in together, and now, Kallman asked herself the question again: Given global warming, could she consider having a child, even with someone she loved?

Conceivable Future cofounder Josephine Ferorelli.(Christopher Salveter)

It was a question she didn’t feel comfortable asking out loud until she met Ferorelli, who had wrestled with similar feelings. Every time Ferorelli heard a piece of positive news about the environment—such as President Obama’s announcement of a climate deal with China—she would be seized by optimism, thinking: “Maybe I could have a baby.” The next piece of bad news would send her back into despair. To both women, this was the heart of the climate-change crisis: not melting ice sheets or crashing oil prices, but the impact on the people you love and the life you could imagine for yourself.

As far as Kallman knew, no one had ever talked about climate change and childbearing choices this way before. In the 1980s and ’90s, scientists had assumed that world leaders would take action to curb the impact of global warming. But by the mid-2000s, emissions were still rising and the worst-case scenarios were playing out, setting the world up for heat waves that could devastate food supplies and rising seas that could drown coastal areas and island nations. So the Conceivable Future parties were a form of consciousness-raising: Kallman didn’t know exactly where the project would lead, but she pictured such conversations happening across the country and helping to create a political platform.

She asked about my own views, and I found myself making a confession. “The part of me that wants to have a child is very much about joy and love,” I said. “I’m not sure that it’s reasonable to try to tamp those feelings down, but I still have these thoughts like, ‘Is it right thing to do?’”

“Who the hell knows?” Kallman replied. “We’re not pushing any single idea. We’re just trying to make a space where people can have their feelings.”

Kallman was still wrestling with her own emotions. “I’m with you on the love thing,” she added. “When I think about the possibility of not having kids, that’s what I would miss the most.”

* * *

“Whenever I talk about having children, climate comes up,” said a buoyant 23-year-old woman named Morgan. “And whenever women I know talk about climate change, the subject of having kids comes up.”

I sat beside her in a room buzzing with the conversations of some two dozen people. We had all assembled on a hot day in July for Conceivable Future’s Seattle meeting, hosted by a local health-food store. Two women in their 20s led the event; both had met Kallman at a conference in April. The participants, ranging from their early 20s to 60s, made a round of introductions. Natalie had recently flip-flopped from never wanting kids to fiercely desiring them. Yin was a first-generation immigrant whose grandparents had raised eight children in Taiwan and didn’t understand why she was deferring having her own family. Frederica, the mother of a toddler and pregnant with a second child, said she was searching for ways to raise kids who would know how to handle themselves even if life in general became less hospitable.

The attendees were a group deeply involved with the environmental movement; several worked for local environmental organizations. That didn’t make them complete anomalies—40 percent of Americans fear that climate change will harm their family members, and a majority under the age of 40 believe it will affect them over the course of their lives. But for the people in the room, the problem was immediate and tangible, and it influenced decisions big and small.

Morgan and I joined a discussion group at the edge of the room. Beside us were two veterans of environmental campaigns in the ’70s. Richard introduced himself as a baby boomer with stepkids but no biological children; Shannon was a former nanny who’d read Ehrlich early in her life and become convinced that it was “completely wrong to have kids—I took a pretty hard stand on it.” But the two were sympathetic toward Morgan, who was born in the early ’90s and could have been the same age as the daughters they’d never had. Morgan said that she had never known a time when global warming didn’t consume her thoughts. “I can’t turn it off,” she added. “I think that gives you permission to do whatever you want as a survivor,” Richard offered kindly. “Yes!” Shannon chimed in.

The tone of these conversations reflected an openness and a lack of judgment that I’d never experienced before on a topic so charged and personal. No one claimed they had the best answer. Instead, we shared a collective grappling with questions of how to cope with the future.

Conceivable Future hosts its first house party in Chicago.(Marya Spont)

Even much of the population movement no longer takes a hard line on such questions. I asked John Seager, head of Population Connection, the organization once known as Zero Population Growth, if he would offer advice for a project like Conceivable Future. I could almost hear him recoil over the phone: “No, I absolutely wouldn’t,” he replied. “These are the most personal and private decisions.” In the years since the publication of The Population Bomb, his group went through an identity crisis, followed by a profound shift in message, when study after study showed birth rates dropping on their own once women had access to contraception, education, healthcare, and legal abortion. (The American birth rate decreased after birth control became easily accessible in the 1970s. Millennials now have dramatically lower fertility rates than any previous generation.) The global population is still surging, and it’s predicted to reach 9.6 billion by 2050. But to Seager’s group, the solutions looked more systemic. “If I could [boil] the whole issue down to two words, it’s ‘Trust women,’” Seager said. “If women are empowered to lead the lives they want to lead, the problem just evaporates.”

* * *

“Becoming a mother is like walking through a door,” a writer friend in her 50s told me. “There’s a whole set of experiences that you can’t understand until you’re on the other side.”

By last fall, I’d finally decided to open that door. My pregnancy arrived in October like a sickness. I wanted to work but lay in bed while my stomach churned; I tried to energize myself by jogging down the street, but afterward, I collapsed on the couch. I alternated between moments of all-encompassing pessimism and moments of unbridled joy. I followed the development of the creature in my abdomen on websites that gave facts about its size: as big as a lentil and then a blueberry, built like a delicate tadpole or a brine shrimp.

Then, after 10 weeks, I began to miscarry. I knew the early weeks of pregnancy were fragile; I had told myself that I would be rational if this happened. But the grief welled up from a part of my psyche that I’d never been aware of before, like an unused muscle. The sadness was deep and physical, torrential and uncontrollable. For weeks, I was embarrassed by all the ways that my body had left me raw. Yet, at times, the grief was like a strange new power—I was as sensitive to the world around me as a barometer. I cried for parents who had to bury children killed by bombings in Syria. I wept for a friend who lost her mother to cancer. I felt like I finally understood what was at stake in these conversations about the future of the planet: the value of what we create and of those we choose to love.

Throughout the winter, I sank deeper into my grief. I slept fitfully and clenched my teeth as I dreamed. I still worked, but barely, as if in a kind of daze. Then I awoke one morning in February to the opening of plum-tree blossoms in my backyard and walked among the decayed remains of last year’s leaves. In the woods nearby, the salmonberries had begun to open their green buds. Last year, spring came early and warm, followed by a summer of record-breaking heat that lit the Pacific Northwest’s forests on fire. Now that it was spring again, I wondered if I would try once more to conceive. I imagined my hypothetical child walking alongside me. What would I say about this place, the renewal of faith, the seasons of life, and whether we could rely on them as we always had? Would I know how to prepare someone for what lay ahead? There was no calculation I could make to tell me the right thing to do. There was only this moment, and the knowledge that everything we choose in it creates or forecloses possibilities for those who live after us.