British Airways (BA) boss Willie Walsh outlined a landmark agreement to cut airline carbon emissions by 50% to the United Nations this week.

Walsh called for a global agreement on aviation emissions to emerge from the Copenhagen summit on climate change in December. Aviation leaders want “a global approach” as an alternative to airlines joining the European emissions trading scheme in 2012.

The BA chief executive led a delegation from airline association IATA, whose 230 member airlines pledged to stabilise net carbon dioxide emissions by 2020 and reduce them by 50% – on the 2005 level – by 2050.

However, the proposal immediately drew criticism because hitting the 50% target would not mean a real halving of emissions. It would be achieved by airlines buying carbon credits from other sectors and paying into carbon offset schemes.

EasyJet, which as a low-cost carrier sits outside IATA, backed a 50% reduction, but said: “Rather than using offsets and buying emission permits from other sectors, we should be reducing absolute emissions.”

IATA considered a 50% absolute reduction, but decided it was not achievable.

The meeting took place as British Council programme leader on climate change Dr David Viner told a Tourism Society seminar in London: “Climate change is happening and it is coming in a more rapid form. We cannot brush this under the carpet.

“Tourism growth will increase emissions, and increasing emissions will impact on tourism. By 2050, one in three summers will be like 2003 – when 35,000 people in Europe died from the effects of climate change.”