I’m getting old enough know where my established curmudgeon status becomes, if not justified, no longer quite as outrageous. I can almost think of today’s teenagers and college students as “youth” and I’m far enough into adulthood I can purse my lips at some of the choices my parents’ generation made and the burdens they will leave behind. Deferring for now a screed against Greta Thornburg and the gerontocracy, I turn to a well-covered source of angst for my generation as well as others – climate change.
Not many days ago now the New York Times had a deeply disheartening story on the disappearance of 30% of bird life in North America over the past 50 years or so. The spot-on allusion to the classic Silent Spring made me think of what I haven’t heard, and perhaps never shall, in terms of birdsong. As birds are only one part of the ecosystem and, I imagine, unlikelt to decline on their on without foregoing or knock-on effects, the headline felt much like a bodyblow I was powerless to defend against. How can I swing back against an invisible opponent? What can I do to help, or at least not to harm – this second part is I think the more important as many of us know we will never or at least seldom directly remediate the damage our consumption and lifestyles do, but we can at least adjust them. A quick perusal of the now-common question “How do I reduce my carbon footprint?” brought me to a few points and immediate action items particular to my own circumstances (that is urban, car-less, homeowners, cooking my own meals, and willing to make changes):
The headline figure we are looking at is that, per capita, Americans generate 15-20 metric tons of carbon per year according to a variety of estimates I reviewed. (Pounds or tons of carbon is clearly the de facto metric among most sources that discuss this issue. Methane, estimated to be 25-30 times more potent than carbon as a greenhouse gas, also comes up.) I saw an estimate that in order to stave off a 2 degree global temperature rise by 2050, the per capita carbon emission level must be brought down to 1.9 tons per person per year. So we are looking at, on average, a 90% or so reduction. Yowzer. But of course, the precisely average person is hard to find, so I needed to know more about my production. Another interesting article, admittedly from a decade ago, estimated the carbon floor of any American to be around 8 tons (this was for a homeless person living in a box) because we all bear the burden of our part in the national carbon infrastructure – roads, the military, social resources, and so forth. This is a critical point – as I estimate my own emissions that I have agency to change, even in a world where I can significantly reduce my own footprint smugness is not in order because my government is emitting, as it were, on my behalf.
When it comes to estimating my own emissions, carbon calculators abound – good news! Getting a good estimate, however, requires a surprisingly deep handle on our everyday habits, and even then the spread of outcomes is surprising. I used carbon calculators from:
- The Environmental Protection Agency (EPA)
- The Nature Conservancy
- CarbonFootprint.com
- Terrapass.com
The EPA alone (and quite rightly given it is a government agency) allows you to download their calculator as a spreadsheet so you can see the assumptions behind it – the other sources are a black box. Using the same inputs, I wanted to see if the calculators gave similar estimates of my household emissions. My inputs were as follows:
- Household of 2 people
- 650 kWh of electricicty used per month
- $46/month of natural gas usage
- $720/year of water
- 100% of electricity is purchased from renewables
- No car
- Public transit use is 250 miles per year each of bus, light rail, and inter-city rail
- Air travel – I use one “big” and one “small” round trip per year, with big being a 3,700 miles trans-Atlantic trip, and “small” being a 1,400 mile trip
With these inputs, what do I get as my household’s carbon footprint?
- EPA: 6,982 pounds (or 3,491 per person) -> 19,702 pounds per person per year is their figure for the U.S. average
- The Nature Conservancy: 29 tons (or 14.5 tons per person) -> 49 tons per household, or 24.5 tons per person, is their figure for the average
- CarbonFootprint.com: 15.6 tons per person, or 31.2 tons total, although they have no clear option to note that 100% of my household electricity is bought from a renewable source, which accounts for 4.6 metric tons per person, so that would be an adjusted 11 tons per person or 22 tons for the household. Their average per person is 16.5 tons.
- TerraPass.com: 13,762 pounds (or 6,881 per person) -> 63,934 pounds is their figure for the U.S. average
This is quite a spread! The EPA’s figure is only 3.2 tons of carbon for the household, while the Nature Conservancy says 29 tons – that’s almost an order of magnitude! What gives? To start, how comprehensive each calculator is. The EPA ignore public transit and flights, focusing almost entirely on home energy use and car-based transportation, and also excludes the impact of diet and other secondary categories like shopping. Indeed, the comprehensiveness of the Nature Conservancy and Carbonfootprint.com is laudable, while TerraPass at least adds flights to the mix.
What are my immediate takeaways from doing this analysis four times?
- Home energy footprint is clearly the primary carbon producer. The fact that I buy 100% renewable electricity through my distributor takes the household footprint down by 4.6 tons (per Carbonfootprint.com) or 2.7 tons (Terrapass) – this is very chunky indeed. Then again, the Nature Conservancy only estimates 1 ton of carbon saved by buying 100% renewable electricity.
- Not owning a car is a big one, and it’s impressive how strong public transit use doesn’t even come close to making a similar footprint. If the other member of my household, C, drove her 2004 Mini Cooper 15,000 miles per year, that’s 5 metric tons of carbon. Clearly, whether it’s the bus or biking, those of us who can avoid owning a car get a great head start. Notably, the exact output of cars is eminently quantifiable thanks to the regulation around emissions.
- Travel by plane can easily negate any savings brought about from using public transit alone. The two flights I input produce 2-3 metric tons of carbon, so frequent flyers are putting those of us on the ground to shame. Fingers crossed battery-powered aircraft come into their own in the new few decades.
- Diet can also produce an outsize result, but one that requires its own analysis to determine. Meat is, of course, notoriously bad for the environment, particularly beef (for which almost 1/4 of the contiguous 48 states is reserved as pastureland) but just how to parse out all the steps in that supply chain is, frankly, an exercise I am not currently interested in pursuing. Eating local and in moderation, and making ones own food as much as possible, seems to me to be a reasonable start.
- A small one, but something that appeals to me, is to stop using the dryer for laundry whenever possible – simply hang dry clothes instead! Composting food waste also reduces the amount of trash I send to landfill and creates more of a virtuous cycle.
Interestingly, the assumptions behind these calculations might moot all but the most concrete of actions I can take (line-drying clothes, diverting food waste to compost, not eating meat, biking, etc.). The cost of gasoline and electricity, as well as the source of the latter, seem to be hovering behind these calculators. As renewables grow as a share of energy production, their enormous environmental cost will shrink – suggesting that the government should continue to build a framework that advantages renewable sources over polluters. Electric cars would do the same, with the proviso that their base load power source would need to be clean to make them live up to their apparent promise. The multiplier effect of carbon-free electricity production therefore makes changing to renewable energy the most compelling thing we can do to reduce our impact.
I feel happy that I’ve taken two major steps in the form of not owning a car and buying my electricity from 100% renewable sources to reduce my footprint. While I can do more around the edges (try to reduce my energy usage by simply consuming less, line-drying clothes, composting, etc.) I think the other clear step I can take is to re-run this analysis annually and buy carbon offsets. TerraPass offers offsets to the tune of ~$25 for 1,000 lbs. of carbon. If I’m doing 15 tons – my worst case scenario from above – that’s around 33,000 lbs. or $825 per annum. That not a little, but it’s also not a lot. If the government were to collect a tax on my for this amount and I had confidence it was actually working, I wouldn’t blink an eye.
I will return to the assumptions behind carbon footprint calculators in the future, but I’m at least happy that for the first time ever, I can put my own contribution to global warming in context of all the figures that get thrown around.
smq.world 