Two travellers can fly the same route and produce very different footprints per day away. The difference is trip length, and the arithmetic behind it is unusually simple.
Transport cost is fixed, not daily
A long-haul flight emits the same amount whether the traveller stays four nights or fourteen. The journey is a one-off charge attached to the trip.
Divide that charge across the days spent at the destination and the per-day figure falls in proportion to the stay.
Accommodation and food, by contrast, accrue daily. They are real but far smaller per day than the amortised flight for any long-haul route.
Short trips multiply the fixed cost
Four separate long weekends abroad in a year incur the journey charge four times. One three-week trip incurs it once.
The number of nights away can be identical in both cases. The emissions are not close.
This is why frequency matters more than distance for most people's travel footprint. A few travellers taking many short trips account for a disproportionate share of aviation demand.
Longer stays change spending patterns
A visitor with two days moves through the highlights, which are the sites already at capacity, and buys from operators geared to rapid turnover.
Someone staying three weeks runs out of highlights in the first few days and starts using ordinary businesses: markets, launderettes, neighbourhood restaurants, local transport.
That spending reaches a wider set of households and stays in the local economy longer, because it is less likely to flow through an international intermediary.
Slower ground transport becomes viable
Overland travel between destinations is usually lower-emission than flying but costs time. On a short trip that time is unaffordable, so internal flights get booked.
With a longer window, a train or ferry that takes a day stops being an obstacle and becomes part of the itinerary.
Each internal flight avoided removes another takeoff, which is the most fuel-intensive phase of any flight.
The constraint is leave, not willingness
Most people cannot lengthen trips freely, because annual leave is granted in short blocks and school terms are fixed.
Where remote work is possible, the calculation shifts sharply, and a substantial share of long-stay demand now comes from people working part of the time.
For everyone else the practical version is fewer, longer trips rather than one very long one, which reaches most of the benefit without requiring a sabbatical.