Rachel Ries’ decision not to have children evolved slowly and through many of the typical reasons, including relationships and career.

But when the 37-year-old Minneapolis singer-songwriter wrote about it in an online testimonial two years ago, her rationale was nothing less than global climate change. “I have no confidence I’d leave my daydream children or grandchildren with a hospitable home on this planet,” she wrote, “and I can’t abide that.”

Her mother, Shirley Ries of Freeman, S.D., was stunned. “I couldn’t even read that article again, it made me so sad,” she said, recalling how her daughter often talked about wanting children. “She would be such a wonderful mother.”

Although Shirley Ries and her husband say they fully support their daughter, they and others agree these can be strange and sorrowful moments for grandparents-not-to-be these days.

It’s hard to know what to say to our adult children when the apocalypse is part of their family planning.

An increasingly big worry for ‘baby doomers’

Fears about climate change are probably not the main reason U.S. birthrates have declined during the past decade, particularly among those under 30. The 2007-09 recession’s lingering effects and burdensome student debt have no doubt played a bigger role.

But at least some of our adult children — maybe more than we realize — say worries about a world disrupted by a hotter climate are causing them to rethink having children. Some have named these reluctant millennials “baby doomers.”

“I’m not sure whether the trend is growing, but the amount of conversation about it sure is,” said Meghan Kallman, a postdoctoral research associate in sociology at Brown University and co-founder of the Conceivable Future project, which calls climate change a reproductive crisis.

Robert Barstow shows his son Michael Barstow the smelly algae hugging the shoreline of the St. Lucie River in Stuart, Florida last year. The algae fouled coastal waterways, closed beaches and drove away tourists. Getty Images

The nonprofit, created in 2014, doesn’t discourage people from having children, but instead creates opportunities for people to express anxieties about the question, in living room forums across the country or on its website, where testimonials range from women with kids pondering their futures to men in their 20s contemplating vasectomies.

A grandparent’s dilemma

Where does that leave grandparents? Josephine Ferorelli, the group’s other founder, says many of these young people are highly conflicted. On the one hand, they are angry at their parents’ generation for creating the climate change crisis. On the other, they want to see their parents become grandparents. “They’re pulled in both directions at once,” she says. “It’s never a totally antiseptic decision you make without the involvement of your family.”

But involvement is limited when it comes to the decision itself. Although I’m nearing the typical age of a grandparent, having grandchildren is decidedly not my choice to make — a fact I knew even before temporary U.S. immigration policy declared grandparents are not bona fide relatives. Our adult children own their reproductive choices.

And even if we’d love to have grandchildren, the world doesn’t need more babies. Global population is now on track to hit 9.6 billion by 2050. A walk through a park or a scroll through a Facebook news feed will reveal that grandbabies are clearly happening for enough of us. Too many children face dire needs on this planet, and it would do us well to consider shifting our energies toward those existing needs, away from our biological obsession and toward intergenerational relationships that nurture in new ways.

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Yet if we’re honest, the biological drives are strong. When one of my friend’s two sons renounced having children — for, yes, among other reasons, fears about climate change — my friend accepted it and got more involved in the lives of her friends’ children. But, she admitted, she still grieved.

I’ve also seen that shadowy specter in my family. My 20-something offspring have not decided about children, yet they have all sounded the alarm about our climate change future. Recently my youngest solemnly pronounced: “I don’t think it’s going to happen for you, Mom.”

What could I say? My instinct is to assure them they’re young, things could change and how do they know anyway? Aim for hope, I say. You are precisely the caring, ethical people who should bring children into the world.

Besides, I thought, hasn’t every generation believed the world was going to end for the next generation?

Not the ‘same as it ever was’

That response, as it turns out, is decidedly unhelpful, Kallman says. It’s exactly the kind of dismissive comment she has heard from many who recount their fears of having children during the Cold War’s nuclear arms proliferation — a political problem that was more far more controllable than the earth processes already unfolding even if we were to stop using fossil fuels today.

“We are at the mercy of really dramatic, unplanned and volatile events, local, physical events,” Kallman said. “And that is dramatically different from the decision of whether to push the red button.”

Indeed, grandchildren today would have climate change as their reality from the moment they are born, its economic and political disruptions shaping their job prospects, their mortgages, their retirement. Much is uncertain, of course, but climate change will strike harder at those with fewer means. Hotter temperatures will even shape the fertility of their children, according to a 2015 study, reducing U.S. births by 100,000 a year by the end of the century if carbon dioxide rates continue unabated.

Local children help clear an oil spill on a beach in New Zealand in 2011. Getty Images

What can you do?

Not all of us will want to face these realities. For those who do, we need to be ready for our adult children’s anger, for their anguish, for their questions, for their worry, for their grief and ours.

“This is a grief-based decision for most people,” Kallman says. “In my experience, anyone who has made that decision has gone through deep, deep waves of grieving, and deep, deep waves of wondering what they’re missing.”

Compassion, she says, is what’s needed. In other words, maybe it’s time for all of us to get our grandparent on, with or without the baby.

In the end, young people wrestling with these decisions need exactly what the best Nonnas, Oba-chans, Abuelas, Babus and Nanas have done through the generations: quietly shown up without fanfare and created opportunities for conversation by simply listening to those fears and hopes.

We can also do more. We can help them with the messy tasks, which includes fighting to reduce our reliance on fossil fuels. And we can pass on the wisdom we’ve no doubt gained from decades on the planet: that life rarely hands us exactly what we planned; so when that happens, we make a new plan.

Rachel Ries, for instance, has decided to move behind her brother’s home to help care for his three young children when she’s not on the road touring. The arrangement, she says, has given her life creative freedom and purpose.

“What matters is my family, the family I already have,” she says. “The family that already needs love, attention and care in light of the impermanence of it all.”