No, Having One Child Does Not Add 60 Tons Per Year to Your Carbon Footprint


This chart is making the rounds, and has been picked up by  Grist, the Guardian, and countless other outlets. It makes a good point – enviros tend to focus on small impact personal mitigation measures like recycling or changing light bulbs, and ignore the big impact personal choices, like flying and having a car dependent lifestyle.

But it also claims that having one child adds 60 tons annually to the carbon footprint of an individual in the developed world.  This makes it sound like one of the most basic aspects of human existence — having a family – is the most climate irresponsible thing you can possibly do. To put that 60 ton number in context, the average per capita carbon footprint in the United States is  about 20 tons – the highest in the world. The global per capita carbon footprint possible consistent with holding climate change to 2 degrees Celsius is somewhere between two and four tons per year, depending on whose numbers you use.

So how does one child born in the developed world add three times the US per capita carbon emissions every year?  Does each newborn come with a Lincoln Navigator and a United Airlines Premier Frequent Flyer Status?

The answer is that the one child does not have such an outsized footprint. The 60 ton number in this chart misrepresents the underlying study – which accounts for the carbon impacts of all future generations going out over 500 years into the future. The chart making the rounds incorrectly attributes these centuries of impacts to the life of the current parent.

I looked into the paper underlying the chart and the sources for that paper, so let me try and explain the error the authors make.  The chart is part of a well-intentioned paper by Seth Wynnes and Kimberly Nicholas appearing in Environmental Research Letters, titled “The climate mitigation gap: education and government recommendations miss the most effective individual actions.” The Supplemental Materials for this paper cite one source for the calculation of the carbon impact of having one child in developed nations, a 2009 paper by Paul Murtaugh and Michael Schlax entitled “Reproduction and the carbon legacies of individuals.”

The important thing to understand about the Murtaugh and Schlax paper is that it does not just calculate the carbon impacts of that one child’s lifetime — rather it looks at the carbon impacts of that child, plus the impacts of that child’s child, plus the impacts of that child’s grandchildren, great grandchildren, etc,  out for almost a millenium, with a diminishing share attributed to that irresponsible 21st century ancestor.  The chart below, from the Murtaugh paper, illustrates how the calculation includes future centuries of carbon impacts:

Murtaugh centuries

Actually, now that I look at it, the calculation does not just extend for centuries into the future, it extends “out to infinity.” So the Murtaugh carbon footprint calculations are not carbon emissions that will occur during any individual’s lifetime.

The Wynnes paper cites the Murtaugh paper as its only source for the carbon impacts of child rearing, and give the annualized carbon impacts of having one child in the developed world as falling into a range between 23,700 kg CO2e (Russia) and 117,700 kg CO2e (US) per year, both in its table one and the following chart:

Wynne Chart.png

But none of the number used by Wynne actually appear in the Murtaugh paper!  The Murtaugh paper does include the following chart for all time combined not annualized out to infinity carbon impacts of one child and all of that child’s children’s children’s children’s children’s descendants:

Murtaught Table 2

Wynne appears to have taken these until-the-end-of-time-totals, converted tons to kg, and divided by average life expectancy to come up with their “annualized numbers” – I can’t get the exact same numbers, but it’s pretty close:

annualized co2 child

So Wynnes, et al, come up with their “annual” CO2 impacts of  having “one” child by taking the cumulative attributable impacts of your children until the end of time and acting as if those impacts occur on an annualized basis during the parent’s lifetime. This is highly misleading, at least.

The decision to have children- and how many – is obviously a highly personal choice. But I think having two children per couple – slightly less than zero population growth – is completely defensible as a climate choice. Any argument that the solution to climate change requires the elimination of future generations in order to avoid a backwards attribution of their impacts will not win any converts to the cause.

One last note: the Murtaugh numbers used by Wynnes are based on the assumption that current per capita carbon emissions in each country will continue unabated until the end of time.  There is not enough fossil fuels on the planet for that assumption to be remotely plausible.



Peak Solar!


This time of year, around the summer solstice, is the annual peak for solar energy around here! I have just a few DIY panels on the roof and side of my house – cost me a couple of thousand dollars five years ago. There are too many shady trees in my leafy exurbia to make a full professional installation worthwhile. The four 150-watt panels I bolted down to the roof face east instead of south and only get about four or five hours of direct sun even during the longish days of late June. With luck I average about 300 watts of actual output from my solar roof for about five hours — about 1.5 kilowatt-hours per day.

Not much by home solar standards — my peak solar production is less than a tenth of the annual average solar energy of a typical home installation.  

But it also cost me less than a tenth of what a professional installation would. The panels charge a 12 volt battery bank, which is connected to an inverter that is usually switched on to cover the house circuit with my refrigerator. The system is not grid tied — either the house circuit is running off the panels and batteries, or it is running off the utility grid.  I have no way to return excess solar power to the grid — that would require a professional installation. But the advantage is that I have backup power in case of a blackout. Two more panels on the south side of the house charge another battery bank and inverter that power a couple of floor lamps and the fan for the wood stove.

Most of the year this DIY system produces enough to keep the fridge running totally off solar power.  If it’s a sunny day, this time of year, there’s enough extra juice to charge my electric motorcycle — three days of surplus sun is about enough for one round trip to work.

Works out about right.  Of course, I have downsized the fridge — more on that later.

Yes, I Actually Got on a Plane Last Week


The Waterkeeper Alliance Annual Conference pretty much the only thing I think is worth the carbon impacts of air travel, and since the conference this year was in Utah and I had to teach my class at 9 am Monday morning, air travel was pretty much the only option.

The good news is that the round trip flight still fits in my 4-ton annual carbon budget — I added up the previous 11 months, and was about 3 tons so far.  So I could just barely afford the one-ton round trip carbon bill for the trip to Utah.

And every time I fly again I am reminded how unpleasant an experience flying has become – the seats are smaller, they charge for baggage and food now, people are irritable. It is pretty to look a the clouds and landscape from above, though.

Individual Climate Action: Now More Than Ever

Bicycle with a basket of flowers next to the Eiffel tower

As President Trump announces the U.S. withdrawal from the Paris climate agreement, state and local leaders have stepped forward to announce their commitment to carrying out the spirit of the Paris accords at more local levels. The governors of New York, California, and Washington have announced a “Climate Alliance”  that is committed to implementing the U.S. greenhouse gas reduction in the absence of the federal commitment. Pittsburgh mayor Bill Peduto objected to Trump calling the City out as benefiting from withdrawal from the Paris Accord, and committed the City to implementation of the Paris targets despite the national withdrawal.

This is good leadership and exactly the right response at the state and local level to the total abdication of climate leadership at our national level.

So what does this mean for climate action at the individual level?  I think individual climate action is now  more important than ever.  And I don’t mean just hopping on a plane to march in a protest or camp out in front of a pipeline carrying fossil fuels to destined to fuel the plane you hopped. I mean setting individual climate reduction goals and meeting them.

Governors Cuomo, Brown, and Inslee, and Mayor Peduto are not all saying, “Gee, why should we deprive ourselves of fossil fuel powered economies to meet the Paris goals when red states like Texas and Florida are going to keep on fouling the planet.” Instead, they  are making the energy future happen now, taking local action even knowing that in the long run to be effectual national and international commitments will be required.

The same leadership principles apply at the individual level. You can give up, say, “why bother reducing my individual footprint when Texas and Florida and China and India and Brazil are all increasing their emissions?” Or you can recognize that social change starts at the individual level and be a climate leader through conspicuous non-consumption.

The Paris Agreement is a set of non-binding, individually determined commitments.  Withdrawal from Paris is completely nonsensical because, if the committed reductions were too onerous, the U.S. could modify its commitments unilaterally, at will. And the U.S. voluntary commitment was never, by itself, enough to limit warming to 2 degrees.  But it was a public declaration of a step in the right direction.

Why not each set our own private Paris? The U.S. Individual Nationally Determined Commitment under the Paris Accord was a 17% reduction in GHG emissions by 2020, and a 26% reduction by 2025. If the States of California, New York, and Washington, as well as localities across the country are willing to commit to that reduction, why not each of us personally?

The Paris Accord asks each nation to take stock, decide for itself how much GHG reduction is fair and achievable for itself, and implement those reductions. Any individual concerned about the climate can make this same determination. My own  Individual Individually Determined Commitment is to keep my direct individual footprint below 4 tons of CO2E per year, about a 75% reduction from the average American footprint of about 20 tons per year. It is achievable for me without giving up anything that is really important.

What is your Individual Individually Determined Commitment? Not every committed climate activist is willing to make the commitment I have, but are we all willing to make some commitment – set a goal, and check at the end of the year that we have met it? Can we all achieve a 17% reduction by 2020 and 26% by 2025, as the Obama administration committed the nation as a whole? Can we each try and meet the EU average footprint of 7 tons per capita annually? At least keep our footprint below the outsized American average footprint of about 20 tons per year?

The Paris reductions were all voluntary.  We can each make our own voluntary commitment to take part in addressing climate change. We are all Paris.

Island Hopping Woth a Small Carbon Footprint (or How Much Diesel Does it take to Run a Sailboat Anyway)

Island Hopping With Small Carbon Footprint (or How Much Diesel Does it Really Take to a run a Sailboat)
We have been kicking around these Bahamas islands for about ten days now in our sailboat.So what’s the carbon footprint of cruising in a sailboat? You would think it was pretty small, with a few solar panels or a wind generator for electricity and sail power to get around.
But you can kick up a pretty big footprint even in a sailboat of you are not paying attention. There is a saying among cruising sailors that every harbor entrance takes its gallon of diesel. If you burn a gallon of diesel entering and leaving each harbor every day, then a cruising couple would be burning as much carbon as driving solo to work every day. A month of cruising like that, and you would have a smaller footprint if you flew to the islands and stayed in a resort cottage the whole time. That doesn’t even take into account impatient sailors who crank up the diesel whenever the wind drops, and all those deck top generators humming in each anchorage every night, and those outboard inflatables buzzing around.
At one gallon per hour of fuel consumption, and at about eight miles per hour cruising speed under power, a sailboat running its diesel engine to get around is just as bad as the worst RV on the road. So we minimize engine use – we limit marina stops to once every three or four days and wait until the last minute to crank up the iron spinnaker. But that diesel needs to warm up for fifteen minutes, and you have to run it hard to keep it happy, so most marinas extract their half gallon of diesel each way anyway. And then there are those sticky situations where running the engine is necessary to keep off the rocks or make that last mile against the tidal current.
We have been practicing the lost art of anchoring under sail – reactively easy to do here in the land of wide open anchorages over coral sands and steady gentle breezes. Most sailing texts tell you to use the engine to set your anchor and break it out – and most sailors do just that. But with a little planning – and an eye to a downwind escape route – you can set and retrieve an anchor under sail in all but the tightest or most crowded anchorages.
We left West End a week ago Sunday. We had to motor into the tight anchorage at Allen’s Cay (1/2 gallon) since we arrived after dark (not recommended) and needed radar to confirm the passage in (no lights or buoys) and find the anchors boats in the dark. The next day we sailed down to Exuma Cays Land and Sea Park at Warderick Wellls, but we needed the engine to make the last mile into the moorings when the tide turned against as well s the wind. We chose a mooring close to the entrance so we would be able to sail out, and paddled our kayaks in the long mile to the registration office. Next day, we sailed around to a mooring by Emerald Rock (great snorkeling!) and Beryl’s Beach. From there we sailed south to Staniel Cay, and spent another half gallon of diesel maneuvering up to their dock full of mega yachts – they kept us waiting in the tidal channel while they docked one ahead of us. Another half gallon to leave the dock on Friday, and we sailed to Gaulin Island with its deserted beach and iguanas. We made and broke anchor under sail at Gaulin, then sailed through Dotham Cut, A narrow slot in the cays the tide poured in against us from the Exuma Sound. There was just enough wind to stem the tide.

The wide open anchorage of New Bight on Cat Island was easy to make and break under sail. We made an excursion to Greenwood Resort for scuba diving on the wall and reef. With folding bikes on board, getting to the resort was zero carbon, since we biked the twelve miles each way to the resort. Well, actually, it turned out to be twenty miles to get there, since we missed the shortcut and misunderstood the directions given by a man walking on the road. But the six mile round trip pickup ride to the dive boat was probably about a half gallon of fuel. Fortunately, the dive site was only about a mile from the beach, so the carbon and hydrocarbon spewing twin 150 two-stroke mercs on the back of the dive boat only ran full throttle for about one minute in each direction – I am going to estimate that as two gallons for the round trip.
From Cat Island, we sailed for Eleuthera. Cape Eleuthera’s south coast was too exposed to anchor, and Davis Harbour marina extracted its gallon of diesel to get in and out. But Governors Harbor was easy to anchor under sail, and if our plans work out and we anchor tonight off Mutton Point near the Looking Glass, and make it out of Fleming Channel without firing up Perky the Diesel, we won’t need to run the engine again until we approach Beaufort Harbor back in the States.
So looks like about five and half gallons of fossil fuel consumption for ten days of cruising the islands, including the scuba outing. Split two ways, that’s about 55 pounds of CO2. Add about five pounds to cover propane for cooking and the couple of kWh of dockside electricity we used, you’ve got about 60 pounds of CO2, living the good life in the tropical islands for ten days. That’s well within my budget.

I want to be a living advertisement for the low carbon good life!


Getting to a Tropical Paradise Without Leaving the Ground

  Or at least, without leaving ground and sea level. And,in this case, the highly manicured paradise of Old Bahama Bay, with carefully placed palms for maximum effect. 

I arrived on Wednesday in my sailboat. I took Amtrak from Newark to Charleston, South Carolina (316 lbs CO2), where the boat had wintered.  I had a pleasant sail down the Wando river to the Charleston Harbor marina in Mount Pleasant (one gal. Diesel, 20 lbs CO 2 for the docking operation).  On Saturday two good sailing friends, Justin Bloom and Dave Burden, joined me and we headed out into the open Atlantic.  After a moderately rough and wet and cold first night of sailing,we got to a sweet spot and had a lovely  four day passage, almost all under sail. We had to run the engine for a few hours when the wind grew calm, but the seas did not, in the middle of the Gulf Stream.  All told, about five gallons of diesel to make the 400 mile passage. Split three ways, that’s about 33 pounds of CO2 per person.  

  For comparison, flying here would have been about 1,000 pounds of CO2. And you don’t really need a boat and offshore sailing skills too get to this particular Paradise at ground level  – pack a family of four into a hybrid, make the road trip from New York to Fort Lauderdale, and grab the daily ferry to Freeport, and you could get here with about the same carbon footprint, still without leaving the ground. Probably quicker, too.

The Carbon Footprint of an Empty House

I have been on break from teaching this semester (I am teaching summers instead), which means that I have been able to enjoy a snowy February at our cabin in the Adirondack mountains. One of the great things about our off the grid cabin is that it uses no energy when it is empty (which is most the time) – the solar panels keep the batteries charged, the wood stove is cold, and with a composting toilet and no running water, there are no pipes to freeze.

Not so with our regular residence downstate. When we leave that house empty in the winter we have to keep the heat on to keep the pipes from freezing (it would be a little too much trouble to drain and winterize the pipes if we are coming back in two weeks). We usually set the thermostat as low as it will go – 45 degrees – which is plenty to keep the pipes from freezing.

Natural gas is the biggest single category of my carbon footprint – 236 ccf of gas last year works out to 2800 lbs of CO2 at the EPA conversion rate, and my share of that (two of us sharing the house) was 1400 pounds – three quarters of a ton out of my four ton budget. That’s the equivalent of 70 gallons of gasoline.

Ironically, we use less gas to heat the house in the winter when I am home than when the house is empty.  That’s because I can usually feed the woodstove enough that the gas heat only comes on on the coldest of nights. But with no one to feed the woodstove, the house temperature drops, and the gas starts burning.

This month, Robin came back downstate several times for meetings and office facetime. Robin is a little less religious about feeding the woodstove than I am, so naturally she turns the gas heat back up (don’t worry “up” is still quite cool, sweater temperatures). Last time she got back to the cabin she said, “Damn, I forgot to turn the heat down.” So we heated an empty house for ten days. Naturally, I was worried about blowing my carbon budget on an empty house. . .

So I checked the gas meter when I got home to see how bad it was. We burned 57 ccf of gas for the first three weeks of February – 680 lbs of CO2. This compares to 33 ccf (400 lbs co2) for all of January, and 39 ccf (470 lbs co2) for all of December – months that were about the same temperature, but either the heat was down or I was home to feed the woodstove.

Robin, who is very patient and indulgent with this whole carbon counting thing of mine, said “Don’t worry about it, since I left the thermostat up, you can put it on my carbon tab.” 

Except. . .  Robin doesn’t exactly have a carbon tab (my life will be a success if a can get just one other person, maybe my spouse for starters, to keep track of their actual carbon footprint . . .). So half of that February heating bill goes on my carbon tab. Next home improvement project: get one of those internet enabled remotely controllable thermostats for the house. . . .

What is the Carbon Impact of a day of Downhill Skiing?

img_0895-1I have been an infrequent alpine skier lately – I just enjoy the free and quiet pleasures of backcountry skiing more than the crowds, liftlines, competitiveness and overall artifice of the downhill ski scene. But here we are just a few miles from one of New York’s premier ski resorts – Gore Mountain – and it has been years since Robin and I enjoyed a day of downhill together – so we jumped in the Prius early one day this week, had breakfast at Cafe Sara in town and made the gondola by nine thirty am after being fitted with ridiculously short rental skis.
So what is the carbon footprint of a day of alipine skiing? Some studies determined that for most skiers, the actual skiing part (lifts and snowmaking) is only about 2% of a skiing holiday. Just getting to the resort is 73% of the typical skiers carbon footprint.
But since we were already here, I needed to figure out the impacts of just the skiing part of downhill skiing, basically the lifts and snowmaking. The best estimate I have been able to find is an Aspen ski resort study, which comes up with about 0.02 tons of Co2 equivalent per skier day. So 50 days of skiing would be one ton of CO2 – about the same as flying round trip cross country.

img_0896 So my one day of skiing, based on the Aspen numbers, would be about 40 pounds of CO2, or about the same as using two gallons of gasoline. That’s what it takes, per person, for two people driving up here from the NY metro area in a 50 mpg Prius.
EXCEPT – lucky for me and my carbon footprint, Gore Mountain recently built a solar farm a few miles south of here in Washington County, and claims that 85% of its annual electrical demand (I.e., lifts and snowmaking) is now sourced from renewable energy. Doubtless some trading is going on to get to that 85%, but I am ok with trading KWh for KWh. Kudos to New York State, which runs Gore, for investing in an energy future that just might include a climate for downhill skiing! So I figure my carbon footprint for a day of skiing, conservatively, at 30% of the 40 pound Aspen number, or about 12 pounds. Gotta leave something for the diesel in the groomers, which are most assuredly not electric. Yet.

A No Carb Very Romantic Valentines Day in the North Wooods

dsc_5051. . .but watch out for the methane in the dinner menu!

We had a lovely Valentines day without any fossil fuels. Since we are up at our cabin in the woods this week, and we have a foot of fresh snow, that meant a backcountry ski outing that ended up at the Garnet Hill log house restaurant in the wilderness.

dsc_4991Started out with heart-shaped pancakes cooked on our woodstove,with local maple syrup. Our stove doesnt have a proper cooktop, but an iron skillet resting on the coals gets plenty hot for pancakes. Spent the morning on work related stuff. In the afternoon, we headed out the front door into the woods and cross country skied three miles up to the William Blake Pond trailhead at the ski shop.

We then skied the six mile backcountry loop through William Blake Pond and the Botheration Pond trail, ending with a magical descent through snow-shagged firs to the Old Farm trail. We were a little late for a dinner reservations at the Log House!


We had an elegant dinner at the Log House at the Garnet Hill nordic center – this rustic restaurant and inn in the wilderness, and has been operating since the 1930s. The lodge has changed hands this year, and the new owners, Jim and Francis Rucker, are enthusiastic about restoring the network of ski trails. The kitchen still serves up Jane’s Onion Pies, along with an improved menu.  Robin had the heart shaped ravioli primavera; I decided I had burned enough calories skiing to deserve my once-every-month-or -so serving of beef, so I had the surf and turf — a delicious lobster meat bearnais over a filet of beef.


After dinner, we skied the three miles back down the hill to our cabin in the dark, our way  – and the occasional snowflake – lit by the beams of our headlamps. The cabin had not cooled down too much, and I threw on the heart-shaped log I have been saving for the right romantic evening. We snuggled up together with a movie on the portable player in front of the fire.

All in all, a memorable Valentines outing — and one that was totally free of fossil fuels.  But not free of greenhouse gas impacts – beef has a pretty hefty GHG impact – about 27 pounds of CO2 equivalent per pound of beef.  This is due in large part to the methane emissions of flatulent cattle.  So mbby 8 oz filet was responsible for about 13 pounds of CO2 greenhouse gas equivalent.

Counting Carbs for Super Bowl Weekend in the North Woods

I am up at our off-grid cabin in the Adirondacks for a few weeks. Though the drive up here is pretty carbon intensive, even in the Prius (43 pounds CO2 per person), once we are up here we can live pretty much carbon free – the cabin is wood heated and solar powered.

Saturday we took advantage of a great new backcountry ski program run by the village of North Creek – they run the town shuttle van up to the top of an old mining road ten miles and a thousand feet up from town.  A series of backcountry ski trails and glades connects back to the ski area next to town. We took the van shuttle twice and made telemark turns in the powder glades until our legs turned to jelly.  The van is a great deal – just five bucks for the ride up, so ten bucks gets to a full day of mostly downhill skiing.

Figuring out the greenhouse carbs of the  van is more of a challenge. The easy way out is to say – well the van is going anyway so my carbon impact is zero – but that is a cop out. The most conservative way to figure it is to take the fuel consumption for the round tip (after all, the cost of deadheading the van back to town is part of the climate cost of the trip up) and dividing by the number of riders. One 20 mile round trip works out to about two gallons of gas at ten mpg, which is about 40 lbs of CO2.  There were 12 skiers on the morning shuttle, but only five of us in the afternoon. This works out to  about 11 lbs of CO2 per person, plus another three pounds for the round trip to town in the Prius. We went to the movies in Indian Lake Saturday night – a 15 mile drive each way, but with five people in the Prius (3 lbs CO2 per person), it hardly added to the carbon budget.

We got back to our carbon diet with a zero carbon Super Bowl Sunday! We spent most of the day skiing on the Garnet Hill groomed cross country trails right from our doorstep.  In the afternoon, I cut up some down and dry branches for zero carbon heat in our cabiin.

We haven’t been to a super bowl party in years, but it seemed like a good way to connect with the crowd here in North River. When I asked our friend Julie for directions to the party at Katie and Jakes, she just assumed I was looking for directions via the ski trails.  After all, there was a nice moon! So we skied up to North Acres farm in the twilight and walked the last half mile up the road.  I rooted for the Falcons out of contrariness, and they lost anyway.  I am told it was an unusually interesting game and unusually interesting commercials. I would agree, not that I would buy anything being advertised at the super bowl.

A few snow squalls left enough of a velvety dusting of snow to ski down the hill on Harvey Road, and the moon came out to light our way down through the woods back to the cabin, which was still warm.

Final score: Pats 34 Falcons 28 CO2 60.