Leading article: Heathrow's clipped wings

It's enough to restore your faith in the battered democratic process. The High Court yesterday ordered the Government to think again about its plan to build a third runway at Heathrow on the grounds that the scheme looks incompatible with Britain's legally binding commitment to cut our carbon emissions 60 per cent by 2050.

The Government's line is that a third runway is vital to the national economy, allowing Britain to compete as Europe's main international hub with Amsterdam's Schiphol, which has five runways, and Charles de Gaulle in Paris, which has four. It insists it has thought through the environmental implications, and made concessions such as limiting the number of flights. But that is not enough. The court was right to back the contention of a coalition of local councils, green groups and residents that government figures just don't add up – and to insist that ministers hold a proper consultation on the impact of the scheme on climate change policy.

Emissions from air traffic are growing faster than any other sector. And yet aviation is a rogue sector which for decades has enjoyed hidden subsidies from untaxed fuel to special bankruptcy protection. Its environmental impact is running out of control. UK air passenger numbers are predicted to rise from 180 million to 475 million by 2030. If the growth in traffic continues unchecked, says the authoritative Tyndall Centre for Climate Change Research, all other sectors of the economy – industry, business, homes and motorists – will be forced to cut CO2 emissions to zero to meet the legal targets.

The rapid growth trajectory for air travel is created by a complex dynamic in which airline manufacturers, airport operators, airlines, air traffic management, consumers and politicians are all entangled. But one thing is clear: it will be difficult to curb passenger volume growth by voluntary means. Some action needs to be taken to shatter the current presumption of an ever-expanding demand for flights. Government is the obvious candidate to break the cycle. Finding an alternative to a third runway at Heathrow is the obvious place to start.