This issue is becoming one of the most important environmental battlegrounds. The bottom line is that we cannot carry on flying and save the climate at the same time.

Now an unpublished study by the world’s leading experts has revealed that airlines are pumping 20 per cent more carbon dioxide into the atmosphere than estimates suggest, with total emissions set to reach between 1.2 billion and 1.5 billion tonnes annually by 2025.

The industry failure to curb its soaring emissions could lead to the “worst case scenario” for climate change, as envisaged by the United Nations.

The report, by four government-funded research bodies, is one of the most authoritative estimates of the growth of pollutants produced by the industry. It was presented to a conference co-organised by the United States’ Federal Aviation Authority but not given a wider audience.

Jeff Gazzard, a spokesman for the Aviation Environment Federation, the group that uncovered the report, said: “Growth of CO2 emissions on this scale will comfortably outstrip any gains made by improved technology and ensure aviation is an even larger contributor to global warming by 2025 than previously thought. Governments must take action to put a cap on air transport’s unrestrained growth.”

Gazzard is right. But how will governments respond? With their heads in the sand…