# 🚲 Transport and Shopping: Choices With the Widest Spread

By Better Wise

Last lesson you ran the numbers on home energy and water, which is the steady background hum of a household. Travel and shopping behave differently: they arrive in bursts, and the gap between the best and worst option on a single trip or purchase can be a factor of 20. That gap is the entire point of this lesson. Stop tuning the 5% items and start spotting the 20x ones.

By the end of this lesson you should be able to:

- Quote rough per-kilometre emissions for the main travel modes without looking them up.
- Compare a flight, a commute, and a purchase by order of magnitude rather than gut feel.
- Name the one or two travel and shopping changes that outweigh a pile of small ones.

## Travel: the same trip can be 20 times different

Everything below is in grams of CO2e per passenger-kilometre (g CO2e/km), the standard unit for comparing modes. Treat the numbers as order-of-magnitude, not precision.

| Mode | g CO2e per passenger-km |
| --- | --- |
| Walking, cycling, e-bike | 0 to 10 |
| Electric train | 15 to 40 |
| Coach | 25 to 40 |
| Bus | 60 to 100 |
| Petrol car, four occupants | 40 to 50 |
| Petrol car, driver only | 170 to 200 |
| Short-haul flight | 180 to 250 |
| Long-haul flight | 100 to 200 |

Aviation ranges are wide because estimates differ on whether contrails and other high-altitude effects are counted. Even the low end is far above rail.

The practical hierarchy is short: **avoid** the trip, **shift** it to rail or coach, then **improve** whatever is left. Here it is as a decision path.

```mermaid
flowchart TD
    A["🧭 Trip you need to make"] --> B{"Can you avoid it, combine it,<br/>or do it remotely?"}
    B -->|Yes| C["✅ Zero emissions"]
    B -->|No| D{"Is there a rail<br/>or coach option?"}
    D -->|Yes| E["🚆 Rail or coach"]
    D -->|No| F["🚗 Car with every seat filled<br/>or ✈️ economy flight"]
```

### Worked example: the 15 km commute

A 15 km each-way commute, five days a week, 48 weeks a year, is 7,200 km. Compare four versions:

| Version | Annual CO2e | Annual fuel or fare cost |
| --- | --- | --- |
| Petrol car, alone | ~1,300 kg | Highest |
| Petrol car, three people carpooling | ~430 kg | Split three ways |
| Bus | ~600 kg | Moderate |
| E-bike | ~70 kg | Lowest |

Two lessons sit in that table. Occupancy is free carbon savings, since a solo petrol car emits roughly 170 to 200 g CO2e per kilometre, and filling all four seats drops the per-person figure by a factor of about four. And the bus is not automatically the winner: a lightly used local bus can be close to a shared car. The e-bike wins on both carbon and cash.

### Worked example: one return flight against a year of driving

A London to New York return trip in economy, roughly 11,000 km flown, produces around 1.5 to 2 tonnes CO2e once high-altitude effects are included. That single trip is larger than the entire year of solo car commuting above, and larger than a year of careful recycling, second-hand shopping, and turning off standby power combined.

This is what "widest spread" means. One decision, made once, can cancel out months of small virtuous acts. That is good news: it means you can be relaxed about the small stuff if you get the big trip right.

### Worked example: the short-haul swap

A 600 km trip taken by short-haul flight emits roughly 120 to 150 kg CO2e. The same trip on an electric train is roughly 15 to 25 kg. Same destination, roughly a tenth of the emissions, usually similar or lower door-to-door time once airport security is included. Under about 700 km, check the train before you check the flight search.

## Shopping: most emissions happen before you own it

For goods, the emissions split into **embodied** (extraction, manufacturing, shipping) and **operational** (electricity, fuel, water during use). For clothing and electronics, embodied dominates by a wide margin. That single fact changes the advice: how long you keep something matters more than how you use it.

| Purchase | Typical kg CO2e |
| --- | --- |
| Cotton t-shirt | 5 to 8 |
| Pair of jeans | 20 to 30 |
| Smartphone | 50 to 80 |
| Laptop | 250 to 400 |
| New car (manufacturing) | 5,000 to 8,000 |

### Worked example: phone versus wardrobe

One new smartphone is roughly equal to ten cotton t-shirts in emissions, and roughly 80% of it is locked in at the factory before you switch it on. So the highest-impact phone decision is not which model, it is when you replace it. Keep a phone four years instead of two and you roughly halve its annual footprint, from around 35 kg to around 18 kg per year. Buying the same phone refurbished cuts the embodied share again.

### Worked example: cost per wear

A pair of jeans at 25 kg CO2e worn 40 times costs the climate about 0.6 kg per wear. Wear the same pair 200 times and it drops to 0.13 kg. No purchase decision beats a longer wearing life, and it is also the cheapest option per wear in cash.

_____ grams of CO2e per kilometre is the rough figure for a solo petrol car. _____ is about the factor by which filling all seats cuts the per-person number. For electronics, the large majority of lifetime emissions come from _____, not from use. Doubling how long you keep a phone from two years to four _____ its annual emissions. One long-haul return flight can emit more than _____.

## Field notes: where people burn effort for nothing

- Check the spread before the habit. If an option is under about 1 kg CO2e, it is noise. If it is over 100 kg, it deserves a real decision.
- Do not buy a new "eco" gadget to become greener. The lowest-carbon purchase is almost always the one you did not make.
- Replacing a working, low-mileage car with an electric one is usually a net increase, because the manufacturing emissions arrive upfront. EVs pay back fastest on high annual mileage and a low-carbon grid.
- Beware checkout offset add-ons. A small payment does not neutralise a flight, and the claim is often unverifiable.
- Fill the car before you upgrade it: one extra passenger beats most efficiency tweaks. Smooth acceleration, correct tyre pressure, and removing roof racks together save roughly 10 to 20% of fuel.
- Buy durable things second-hand first. The embodied emissions were already paid by someone else.

## What to carry into the checkpoint

- Travel and shopping choices spread wider than home energy choices, so a handful of decisions dominate your total.
- Per passenger-km, rail and coach sit at the bottom, solo petrol cars and short-haul flights at the top, and occupancy changes the car figure dramatically.
- For goods, embodied emissions dominate, so lifespan beats efficiency and "green" labelling.
- The avoid, shift, improve hierarchy applies to both trips and purchases: skip it, substitute it, then optimize what remains.

Next up is the checkpoint for this module, where you will combine food, home, travel, and shopping estimates into a single household picture and pick your top three moves.

Front: Rough emissions of a solo petrol car per passenger-km?
Back: About 170 to 200 g CO2e.

Front: How does car occupancy change per-person emissions?
Back: They divide by the number of occupants, so four people cut the figure by about 75%.

Front: Per-km range for electric rail?
Back: About 15 to 40 g CO2e, far below a solo car or a flight.

Front: Why is a short-haul flight often worse per km than a long-haul one?
Back: Takeoff and climb burn a large share of fuel over a short distance, roughly 180 to 250 g per km.

Front: What share of a smartphone's lifetime emissions comes from manufacturing?
Back: The large majority, often 80% or more, so lifespan is the main lever.

Front: Order of magnitude for a new cotton t-shirt?
Back: Roughly 5 to 8 kg CO2e.

Front: Order of magnitude for a new laptop?
Back: Roughly 250 to 400 kg CO2e, mostly embodied in manufacturing.

Front: Why does keeping a device twice as long halve its annual footprint?
Back: Embodied emissions are spread across the years of use, so more years means fewer kg per year.

Front: State the three-step travel hierarchy.
Back: Avoid the trip, shift to rail or coach, then improve the vehicle or fill its seats.

Front: Typical fuel saving from eco-driving habits?
Back: About 10 to 20%, from smooth acceleration, correct tyre pressure, and removing roof racks.

Front: Which single purchase usually dwarfs clothing and gadgets?
Back: A new car, at roughly 5 to 8 tonnes CO2e to manufacture.

Front: What makes a choice a wide-spread choice?
Back: The best and worst options differ by 10x or more, so effort there pays back most.

Front: Why check a long-haul return flight first?
Back: It can emit roughly 1.5 to 2 tonnes CO2e, more than a year of average car commuting.

---

## Contents

Part of [🌱 Sustainable Living and Climate Awareness](https://everwise.study/courses/sustainable-living-and-climate-awareness.md)

- **🌍 Climate Science in Plain Terms**
  - [☀️ The Greenhouse Effect Without the Jargon](https://everwise.study/courses/sustainable-living-and-climate-awareness/greenhouse-effect-without-jargon.md)
  - [🔢 CO2e, Scopes, and Reading a Carbon Footprint Number](https://everwise.study/courses/sustainable-living-and-climate-awareness/co2e-scopes-reading-carbon-footprint.md) (sign-in required)
  - [✅ Checkpoint: Climate Foundations](https://everwise.study/courses/sustainable-living-and-climate-awareness/checkpoint-climate-foundations.md) (sign-in required)
- **🛒 The Big Four: Food, Home, Travel, Shopping**
  - [🥦 Food Footprints: Meat, Dairy, Waste, and Fair Swaps](https://everwise.study/courses/sustainable-living-and-climate-awareness/food-footprints-meat-dairy-waste-swaps.md)
  - [🔌 Home Energy and Water Savings That Pay Back](https://everwise.study/courses/sustainable-living-and-climate-awareness/home-energy-water-savings-payback.md)
  - [🚲 Transport and Shopping: Choices With the Widest Spread](https://everwise.study/courses/sustainable-living-and-climate-awareness/transport-shopping-choices-widest-spread.md) — this lesson
  - [✅ Checkpoint: Everyday Emissions](https://everwise.study/courses/sustainable-living-and-climate-awareness/checkpoint-everyday-emissions.md)
- **♻️ Waste, Greenwashing, and Habits That Stick**
  - [🧰 Waste, Repair, and Reuse: Worked Examples](https://everwise.study/courses/sustainable-living-and-climate-awareness/waste-repair-reuse-worked-examples.md)
  - [🔍 Sustainable Purchasing and Spotting Greenwashing](https://everwise.study/courses/sustainable-living-and-climate-awareness/sustainable-purchasing-spotting-greenwashing.md)
  - [📋 Building a Household Plan That Cuts Emissions and Bills](https://everwise.study/courses/sustainable-living-and-climate-awareness/household-plan-cuts-emissions-and-bills.md) (premium content)
  - [✅ Checkpoint: Green Choices and Habits](https://everwise.study/courses/sustainable-living-and-climate-awareness/checkpoint-green-choices-habits.md) (premium content)
- [Course cheatsheet](https://everwise.study/courses/sustainable-living-and-climate-awareness/cheatsheet.md) (premium content)