I have always been good with money and careless with carbon. In Singapore the two never felt connected. The trains are cheap and everywhere, so I never thought about what getting around cost the planet. Then I booked my Singapore Airlines flight to London for my exchange at UCL, and an online calculator gave me a number I couldn’t ignore: roughly 3.4 tonnes of CO2 for the return trip, more than a person in many countries emits in a whole year. I landed for the first time in carbon debt, and decided to spend what was left carefully.
The bus to campus cost £1.75 and the train £3.90, so every morning I walked the thirty minutes from Ifor Evans Hall to Euston Square instead, using Citymapper. I did it for my wallet and only noticed weeks later it was paying down my carbon too. Money and carbon pointed the same way, and London’s walkable streets and cycle lanes made spending less of both a pleasure. Somewhere along those mornings I stopped walking to save money and walked because I loved it.
I used the same logic on bigger journeys, booking trains through Trainline rather than flying domestically and letting the rail network show me the country: Arundel for tulips, Salisbury for Stonehenge, the Seven Sisters cliffs, and Edinburgh for the mountains. To Paris I took the Eurostar, which produces around 90% less carbon than the equivalent flight. To Dublin I took the train to Holyhead, then the ferry: slower and more of a faff, but a fraction of flying’s emissions. I travelled in fewer, longer trips instead of short weekend flights, getting more memory out of every gram of carbon. Britain is legally bound to reach net zero by 2050, which made these choices feel ordinary, not heroic. They follow SDG 13: Climate Action and SDG 11: Sustainable Cities.
The smallest daily choices added up too, under SDG 12: Responsible Consumption. Too Good To Go let me buy surplus food cheaply, and I bought my clothes second hand on Vinted. None of it felt like going without. On my last day, with clothes that wouldn’t fit my luggage, I walked the ten minutes from Camden to a charity shop called Tracy Treasures and gave them away. Charity shops are everywhere here; what I couldn’t carry home could still be worth something to someone else.
In Singapore, convenience had made travel invisible; London made me feel the cost of every journey, and showed me the low-carbon choice is usually the cheaper and lovelier one. I’m flying home in carbon debt I’ll keep paying down, but also in credit: a love of walking, and habits I’ve banked for good. That is the real return on a sustainable exchange.
References:
(Curb6, 2026) SIN–LHR flight ≈3.4 t CO2e return.
https://curb6.com/footprint/flights/london-lhr/singapore-sin
(UK Government, 2019) UK net-zero-by-2050 target.
https://www.legislation.gov.uk/uksi/2019/1056/made
(Eurostar, n.d.) ~90% less CO2 than flying.
https://www.eurostar.com/uk-en/sustainability
(Our World in Data, 2023) Ferry vs flight emissions.
https://ourworldindata.org/travel-carbon-footprint
(United Nations, n.d.) Sustainable Development Goals.
https://sdgs.un.org/goals
