In response to the rising number of tourists and their greater mobility, transport by air, road, and rail is continuously increasing ? a report by the International Civil Aviation Organisation (ICAO) stated that the number of international air passengers world-wide rose from 88 million in 1972 to 344 million in 1994. As a consequence, tourism now accounts for more than 60% of air travel and is therefore responsible for an estimated 7% of total carbon globally. This percentage is likely to rise considerably with the number of international travellers expected to increase from 594 million in 1996 to 1.6 billion by 2020, thus adding greatly to the problem unless steps are taken to reduce emissions. One study estimated that a single transatlantic return flight emits roughly half the CO2 emissions produced by all other sources (lighting, heating, car use, etc.) consumed by an average person yearly. As such, passenger jets are the fastest growing source of greenhouse gas emissions.

According to the Natural Resource Defence Council (NRDC), fuel burned by aeroplanes puts nitrogen oxide and water vapour at 30,000 feet. These two additional greenhouse gases together give as much as twice the global warming effect as the carbon dioxide released by the aeroplane. One tree offsets the carbon dioxide emitted by the aeroplane over 4,000 miles and two more trees offset the greenhouse effect caused by the nitrogen oxide and water vapour.

Noise pollution from aeroplanes, cars, and buses, as well as recreational vehicles such as jet skis, is an ever-growing problem of modern life. In addition to causing annoyance, stress, and even hearing loss for humans, it causes distress to wildlife, especially in sensitive areas.