The UK government's environmental czar is unconvinced by industry claims that carbon emissions could return to 2000 levels by 2050.
Appearing before the parliamentary transport committee, Environment Agency chairman Lord Smith said he further doubted the ability of the European Union Emissions Trading Scheme to encourage reductions due to the prevailing low price of carbon. He said it is foolish and wrong to believe the UK could hand on responsibility for emissions by trading its way out of it.
"It's a tool that can be used, but it's not the only one," he said.
Responding to questions over whether the true environmental cost of aviation was being met, Smith said he did not believe either passengers or airlines were paying to cover climate change and health effects of greenhouse gas emissions, as well as other local air pollution impacts.
"The aviation industry is now having to make its case more clearly than it was before, and rightly so. The question of the expansion of aviation into the future needs to be related to the climate change targets we have set as a country and I don't think that has yet been done, either by the aviation industry or, indeed, by government."
The recent claims to which Smith referred were made by Sustainable Aviation, a coalition of UK airlines, airports, aerospace manufacturers and air traffic management providers, which in December published its first report mapping the air transport industry's carbon emissions to 2050.
Its forecast of returning to 2000 levels by 2050 relies heavily on a vision of a maturing UK air transport combined with anticipated efficiencies from new airframe and engine technology, advanced air traffic management and operations, as well as the sustainable fuel development - although market-based measures such as cap and trade emission schemes were not counted.
Smith said the UK needed to make a strategic decision as to how in 2050 the 20% of national carbon limit would be allocated between sectors. "Where aviation fits into that picture, and to what extent, seems to me to be the most important question that we need to decide if we're looking at the long term future of the aviation industry," he said.
He also confirmed that he had advised against a third runway at London Heathrow chiefly due to the impact on local air quality, in particular because nitrogen dioxide levels are already being breached around the airport.