A few years ago, a UK commentator said that one transatlantic flight, with its impact on the climate, was tantamount to child abuse.

The comparison was inappropriate, and some would say laughable.

But on 28 May the Independent newspaper in Britain carried a set of comparisons that can help more informed thinking and reflection on the impact of flying.

* Air travel produces 19 times the greenhouse gas emissions of trains; and 190 times that of a ship.

* Aviation could contribute 15 per cent of greenhouse gases each year if unchecked.

* Greenhouse gas emissions caused by UK air travel have doubled in the past 13 years, from 20.1m tons in 1990 to 39.5m tons in 2004.

* During the same period emissions from UK cars rose by 8m tons, to 67.8m tons.

* One return flight to Florida produces the equivalent CO2 of a year's average motoring.

* Emissions at altitude have 2.7 times the environmental impact of those on the ground.

* Air travel is growing at UK airports at an average of 4.25 per cent. In 1970, 32 million flew from UK airports; in 2002, 189 million. By 2030 some 500 million passengers may pass through UK airports.

* Cargo transportation is growing by 7 per cent a year. In 1970, 580,000 tons of freight were moved by plane; in 2002, 2.2 million tons. It is forecast to reach 5 million tons in 2010.

* 50 per cent of the UK population flew at least once in 2001.

* Flying 1kg of asparagus from California to the UK uses 900 times more energy than the home-grown equivalent.

full story from Michael McCarthy, Marie Woolf and Michael Harrison here

CH