I take an interest in the environment because I live in it. Trying to make choices that reduce my carbon-footprint is one way I try to do my part to maintain it.
Human-powered travel must surely have the least impact right? But moving around requires energy which come from food, so you have to eat more, and food does have a huge environmental impact. I decided to crunch some numbers and find out if I could have reduced the carbon footprint of this trip by taking a bus or other mode of transportation instead of the unicycle.
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Human-Powered Transportation
It all comes down to diet: different foods come from different sources, require different processing and ultimately have very different carbon impacts. I found an interesting chart over at Fat Knowledge republished from the book Food, Energy, and Society(I did the metric conversions so errors there are mine):
| Food |
lbs CO2/100 Cal |
gm CO2/100 Cal |
| soy |
0.01 |
5 |
| corn |
0.02 |
9 |
| veg (avg value) |
0.03 |
14 |
| potatoes |
0.05 |
23 |
| apple |
0.06 |
27 |
| herring |
0.06 |
27 |
| chicken |
0.37 |
168 |
| milk |
0.62 |
281 |
| eggs |
0.64 |
290 |
| tuna |
1.05 |
476 |
| salmon (farmed) |
1.07 |
485 |
| fish (avg value) |
1.33 |
603 |
| pork |
1.99 |
903 |
| beef (grain fed) |
3.04 |
1379 |
| lamb |
5.71 |
2590 |
| shrimp |
6.79 |
3080 |
As you can see the amount of CO2 for every hundred calories of energy follows a general trend:
Veggies < Animal Products < Red Meat.
Eating lamb produces 571 times more CO2 than soy.
Because meat products produce such large emission, I am a vegetarian (lacto ovo). So how do different diets stack up? Again from Fat Knowledge:
| Diet |
tonnes/yr CO2 |
gm CO2/100 Cal |
| Vegan |
0.19 |
13.8 |
| Lacto Ovo |
1.22 |
88.6 |
| Avg American |
3.29 |
238.8 |
| Mad Meat Eater |
6.70 |
486.4 |
These numbers are based on a 3774 calorie diet which includes wasted food.
3774 cal * 365 days in a year = 1377510 calories per year, divided by the yearly CO2 tons gave the CO2 per calorie column.
Unicycling Across Canada
According to Calorie Count, unicycling burns 340 calories each hour. "Unicycling" is a pretty broad term; usually not applied in the touring sense.
Calorie Count also says that biking 20-23kph burns 544 calories/hour and 23-26 burns 680.
I average just over 20, and unicycling is less efficient than bicycling, so I'll assume 600 calories/ hour.
The total trip distance is about 4700km. At 20kph that means 235 hours of riding.
235 hours at 600 cal/hour means 141 000 calories extra I must consume.
141 000 calories at 88.6gm CO2/100 Cal means a total carbon footprint of 124 926gm CO2
Unicycling Across Canada has a total carbon footprint of 0.12 tonnes CO2
Some Context
| Activity |
Carbon Emitted |
| Unicycling Across Canada |
0.12 Tonnes |
| Same trip on an "Average American" diet |
0.34 Tonnes |
| Biking across Canada* |
0.13 Tonnes |
| In a hybrid Civic |
0.51 Tonnes |
| In a Honda Accord |
0.82 Tonnes |
| In a Jeep Cherokee (SUV) |
1.12 Tonnes |
I'll get some more numbers up here when I find good sources, eg the footprint of bussing, training, and flying, maybe walking too.
* I don't have a good reference for this yet