• Bicycle: 0 tCO₂e (Zero usage emissions. Bicycle manufacturing footprint is minimal and amortized over several years of use.)

• Trains: 0,02 to 0.09 tCO₂e

  • Ho Chi Minh City to Hanoi (Vietnam): 1,726 km (diesel line) -> ADEME factor ~40 gCO₂e/passenger-km ≈ 0.069 tCO₂e

  • Guangxi to Guizhou (Nanning-Guiyang HSR, China): 512 km (electric) ≈ 0.007 tCO₂e

  • Guizhou to Yunnan (Guiyang-Kunming HSR, China): 465 km (electric) ≈ 0.006 tCO₂e

  • Yunnan to Boten (Kunming-Laos Border HSR, China): 590 km (electric) ≈ 0.008 tCO₂e

    Methodology for Chinese high-speed rail: Estimated power consumption (~0.023 kWh/passenger-km) × carbon intensity of the Chinese grid (560 gCO₂e/kWh, Ember 2024) ≈ 13 gCO₂e/passenger-km. Note: Yunnan relies heavily on hydropower, so real intensity is likely lower than the national average used here.

Tent, Homestay, or Guesthouse ≈ 0,80 kgCO₂e

For reference (repartition 1/3 each) :

• 1 night under a tent ≈ 0 kgCO₂e

• 1 night in a homestay ≈ 1 to 3 kgCO₂e

• 1 night in a simple guesthouse (without air conditioning) ≈ 5 to 10 kgCO₂e

Flexitarian Diet: ~0,96 tCO₂e

Mostly plant-based, accepting local meals offered or found along the route.

For reference, a flexitarian diet in Western Europe is estimated at 1.5 to 1.8 tCO₂e/year compared to ~2.4 tCO₂e/year for a standard meat-heavy diet (ADEME). This evaluation had been adapted to Asian diet’s impact (Poore & Nemecek)

• Digital Hardware (Camera, Phone, Laptop, E-reader): ≈ 0.06 to 0.07 tCO₂e/year

  Calculated by amortizing manufacturing emissions over equipment lifespans:

  Laptop (156 kgCO₂e ÷ 4 years ≈ 39 kg/year);

  Smartphone (32.8 kgCO₂e ÷ 3 years ≈ 11 kg/year);

  Camera (estimated by analogy ≈ 10 kg/year);

  E-reader (≈ 4 kg/year).

• Textiles & Clothing: ≈ 0.04 tCO₂e Minimal wardrobe replacement over one year of travel (cotton t-shirt ≈ 7 kgCO₂e, technical trousers ≈ 20 kgCO₂e).

• Website Traffic (Squarespace): ≈ 0.002 tCO₂e/year (2 kgCO₂e)

  Calculated for approximately 1,000 views/year. At an average of 1.5 to 2.5 gCO₂e per view due to image-rich blog entries, 1,000 visits represent roughly 2 kg of CO₂e per year? so less than driving a car for 10 kilometers.

• Social Media: ≈ 0.02 tCO₂e/year (30 minutes/day at 2.10 gCO₂e/minute across major social apps according to Greenspector 2021).

• Initial On-Demand Print Run (~50 copies): ≈ 0.20 tCO₂e

  Calculated at ~4 kgCO₂e per copy. Literature cites a range of 2.7 to 7.5 kgCO₂e per book depending on paper weight and ink coverage (Wells et al. 2012; Impakter 2025). The upper end of the scale is used here because this is a heavily illustrated photo book printed on coated paper in a small print run.

• Initial Distribution (Independent Bookstores / Photo Festivals): Negligible (< 0.01 tCO₂e). Shipping around 50 copies (under 20 kg total) over short to medium distances remains an order of magnitude lower than production itself.

• Print-on-Demand Future Sales: ≈ 4 kgCO₂e per copy sold Global print-on-demand platforms (Blurb, IngramSpark, Lulu) print near the buyer, drastically reducing international transport emissions compared to a centralized print run.

The total project-related operational footprint comes to approximately 2,10 to 2,17 tCO₂e (depending on if I take the train in Vietnam).

For comparison, the average annual carbon footprint of a French citizen is estimated at 8.2 tCO₂e/year (SDES/ADEME 2025).