I've got some of the standard maternal guilt that is ingrained in our culture: I worry that I am not spending enough quality time with my son, while also worried that I may be a "helicopter" mother. But my main source of guilt springs from the mere fact that I created a person. Specifically, an American person who will inevitably leave a large carbon footprint. It's environmental guilt.

There is a little voice in my head that chastises me every time I forget to bring my canvas bags to the grocery store, when I throw away coffee grounds that should be composted, or when I drive when I could walk or take the subway. The thing is, I'm just too damn tired sometimes. I have a one-year-old.

And that little voice; well, it's actually my husband's voice. I married an environmentalist who bikes to work and stops by the farmers market to drop off our compost twice a week. Usually, I love this about him. He challenges me to be a better person. But in 10 years of togetherness, our most heated arguments have been about my failure to live up to his environmental standards.

"I'm not willing to gag every time I enter the kitchen for your precious banana peels!" I yelled one summer when his composting experiment in our kitchen (which is not air-conditioned) turned into a repulsive, foul-smelling goo.

And later: "I want to use cloth diapers, too, but it's day 10 with pee and poop soaking through them and onto my clothes, and we're 15 loads of laundry in, and I'm the one doing it all!”

His comeback was to suggest I pay closer attention to our newborn’s "pee cycles" and change his diapers more often.

When we started thinking about having children years ago, creating pro and con lists, I wrote "environmental impact" in all caps on the cons side of the page. I'd read the 2009 Oregon State University study that measured carbon legacy—the carbon footprint you, your children, and their descendants leave—and it gave me pause.

Americans are huge consumers of energy: "an extra child born to a woman in the United States ultimately increases her carbon legacy by an amount (9,441 metric tons) that is nearly seven times the analogous quantity for a woman in China (1,384 tons)," says the study.

The researchers did some complicated calculations having to do with average life expectancy, per-capita emission rates, average fertility rates, and how many descendants a person will have to get to that number, but any way you slice it, Americans' carbon legacies are among the worst in the world.

The researchers preempted the collective guilt response from parents ("But what if I recycle and take public transportation?"). They measured the potential savings of replacing your old car, fridge, windows, and light bulbs with energy-efficient versions, driving less and recycling. Those lifestyle changes were insignificant compared to the environmental burden of producing another human being: a Prius-driving, composting, American woman "would save about 486 tons of CO2 emissions during her lifetime, but, if she were to have two children, this would eventually add nearly 40 times that amount of CO2 (18,882 t) to the earth’s atmosphere."

The study suggests that women "have one less child," a confusing directive when, in my case, I wasn't sure whether I wanted to try for one child, two or none.

When I brought up the environmental impact of procreation with my husband, though, I was astounded that he—the man who composts used Kleenex and picks up other people's trash when we walk through the park—didn't feel as pained about it as I did.

"We're only talking about having one child," he said. "We're not even fully replacing ourselves."

"But the impact is so much bigger than whether we recycle or whatever," I said, shocked by his nonchalance.

"Yeah. But if we only have one, it's still a long-term net reduction. I think we should do it." He shrugged and went back to chopping vegetables for a Diet for a Small Planet recipe.

Ultimately, in my protracted angst about whether to attempt baby-making, something my mom said tipped the balance. I was babbling on about the environment, the responsibility, the financial strain.

"All of those are good points and whatever you decide is OK with me, but I will say that the love you feel for a child—the love between parent and child—it's like nothing else. And I just think more love is better than less love."

More love is better than less love. Right. Love, the missing item on my pro and con lists, the ultimate renewable energy source.

Still, when my belly began expanding, the weight of bringing a new human being into the world also grew. Besides the environmental toll, it seemed selfish to create a little person to care for when so many people don't get the care they need. That was my thought as I trudged past an increasing number of homeless people on my way to my office, a nonprofit writing program where foster kids write stories about their abuse, then back to my apartment building where low-income residents are slowly being pushed out. The guilt heaped up, though I knew it was privileged guilt, a luxury of feeling possible in my upper-middle-class strata, where the issue is not how to get food on the table, but how to get organic, hormone-free food on the table made from sustainably sourced lumber. Then I felt guilty for feeling guilty.

I put together a nursery full of secondhand furniture, clothes and toys (with images from the Story of Stuff dancing through my head), but somehow the big box stores knew what I was up to and assaulted me with catalogs I didn't ask for and emailed coupons enticing me to the aptly named Buy Buy Baby store. I read an "article" sponsored by Disney that listed the "Top 100 Newborn Essentials" to buy and I felt simultaneously appalled by the amount of stuff the baby industrial complex was pushing and panicked that I didn't have enough of it.

I tried to subvert the consumer culture by DIYing, thinking my carbon footprint would be minimized if I didn't buy more crap. Instead of buying a pumping bra, I cut holes in my sports bra; instead of buying tiny baby washcloths, I cut up some old cloth diapers to size; instead of buying wet wipes, we made our own out of Seventh Generation napkins. All those things literally fell apart, and I sheepishly went online to order replacements, delivered within 24 hours via fuel-guzzling jets and trucks. At least, I told myself, because we're city dwellers who live in a small apartment and get around mostly by foot and subway, we have comparatively low carbon emissions (23,000 pounds of carbon annually, according to this EPA calculator, versus the average household emissions of 66,000).

Soon enough, my son's smiles and giggles distracted me from my constant low-level guilt. He was finally a real person, toddling around the park, fascinated with the sparrows and squirrels, who had no idea he was soiling diapers that would become landfill waste and gobbling up avocados and bananas that were shipped across the globe. My concern about the environment became more concrete as I imagined him navigating a world of extreme weather. It seemed increasingly important to push for big solutions, starting with electing politicians who understand the seriousness of climate change and support tough regulations on carbon emissions.

My husband and I strapped our baby into a carrier and joined more than 300,000 others in the People's Climate March in September. After ogling the colorful protest signs and the vast crowd, my son fell into deep sleep and I got to chat with some parents who, I assumed, must be as guilt-ridden as I was about breeding.

"Well, sure, I think when you're deciding to have children or not have children, you think about what kind of world are they going to live in," one mom activist said to me carefully.

But she didn't like my question about the contradiction between being an environmentalist and a parent.

"Having a family is part of being human…I wouldn't tell someone 'you shouldn't have children' as much as I wouldn't tell someone not to live past 100 because they're a drain on the environment. It's a value judgment about who should be alive and who shouldn't be alive. Being able to have kids and have a livable climate should be the goal," she said.

I felt better after talking to her, though I realized that this complex issue has kept me vacillating between hope and despair depending on what I've just read or heard. But, at the risk of sounding hokey, there's something about loving someone I expect will outlive me that more often tips the scales in favor of hope these days. So my mom was right that more love is better than less love, but by combining that with my persistent guilt, I hope that my son and I both become good stewards of the planet. Especially if he becomes a brilliant engineer who figures out how to get us off fossil-fuel dependency, cleans up the Great Pacific Garbage Patch, and in his spare time, invents a disposable diaper that can be recycled.