Other than one summer when I was 17, I've never owned or driven a car, and cycling has never been an alternative to that. My commuter journeys over the years have always been by public transport or by bicycle. By bike because it's so much more pleasant, unless the weather is foul, or because there was no public transport. I spent a winter once living at Sandbanks in Poole (back in the days when you could rent an almost unheated holiday home for peanuts in the winter), and I had no option but to cycle to work as there were no buses outside of the summer season. One particularly miserable ride is still etched in my memory, when we'd had a rare heavy snowstorm and I was riding in heavy rain and howling wind the next day. But I digress.
I very much am an environmentalist and I'm very supportive of the use of bikes for that purpose, and that's to a large extent down to my having traveled a lot and seen so much of the natural beauty of the planet. The loss of Himalayan glaciers that provide so much of the dry season irrigation to parts of Northern India? I've trekked alongside the Khumbu glacier in Nepal, and its loss would be a tragedy.
Or the seasonal variations in the Tonlé Sap lake and river system in Cambodia, which is the result of an amazing natural cycle (seriously, check it out on Wikipedia), producing a fish resource that's essential in a poor and developing country. It could be destroyed by global warming and millions could lose a critical food source - just so rich people in the developed world can carry on driving their big cars. I've been there too, and my most endearing memory is of disarmingly friendly and welcoming people who have suffered a truly horrible recent history, but who are among the best people I've ever encountered.
The fertile north-eastern plateau of Thailand produces vast quantities of rice which feeds millions, and it's among the best quality rice in the world. But the essential rainy season is becoming increasingly erratic, and what used to be frequent double harvests are becoming rarer. It's a high-density food resource, and we can't afford to lose it. My wife of 30 years is from a long line of Thai rice farmers.
I could go on... but then I'm held back by the miles I've flown in the course of my travels, and my resulting feelings of hypocrisy. Long-distance high-altitude flying is especially damaging, and over the past 30 years I've averaged probably 2 or 3 such flights per year. So who am I to preach to others?