The government's plans for a third runway at Heathrow were dealt a blow today after a high court judge agreed with campaigners that climate change threats had not been taken seriously enough.

In a complex judgment, Lord Justice Carnwath declined to quash the controversial planning proposal but branded the original position adopted in the government's authorisation as untenable.

The judge ordered Whitehall officials to give a formal undertaking that they would carry out a further policy review.

The lengthy judgment was hailed as a victory by both the transport department and the coalition of local councils, green groups and residents who had gone to the courts objecting to the plans for a third runway, saying it was inconsistent with government targets to cut carbon emissions.

On the question of whether the government had taken threats to global warming into consideration sufficiently, the judge remarked: "The [objectors'] submissions add up, in my view, to a powerful demonstration of the potential significance of developments in climate change policy since the 2003 white paper. They are clearly matters which will need to be taken into account under the new airports NPS [national policy statement]."

But he added: "I am not able, at least on the material before me, to hold that any of these points amounts to a 'show-stopper', in the sense that the only rational response would be to abandon the whole project at this stage."

In the course of his judgment, Lord Justice Carnwath also observed: "I find myself unable wholly to support the position taken by either party".

A further hearing is due next month to consider costs and whether fresh legal orders need to be made.

Ministers insisted that today's ruling would have little practical impact on their current planning policy while campaigners – who posed for photographers with champagne glasses outside the royal courts of justice in central London – relished the judicial reproaches and insisted it would ultimately prevent construction.

The Conservative leader, David Cameron, whose party opposes a third runway, claimed the judgment was a severe embarrassment for the government: "[Their] policy is in tatters. They made the wrong judgment about this, we made the right judgment ... There is no case for it on environmental grounds, there is no strong business case for it."

Speaking in Brussels, however, the prime minister, Gordon Brown, insisted a new runway was vital to "help secure jobs and underpin economic growth", adding that the government had backed an extra runway "only after a detailed assessment showing that the strict environmental limits for expansion could be met".

The coalition opposed to the new runway includes WWF-UK, Greenpeace and the Campaign to Protect Rural England (CPRE). In a joint statement, the groups said: "If the government wants to pursue its plans for Heathrow expansion it must now go back to square one and reconsider the entire case for the runway."

Hayes and Harlington Labour MP John McDonnell, who has led the campaign against the expansion of Heathrow for 30 years, said: "In essence, this judgment means that the game is up for a third runway at Heathrow and I am calling upon the government to accept the inevitable and lift this threat to my community."

But the transport secretary, Lord Adonis, countered their claims: "I welcome this court ruling. Heathrow is Britain's principal hub airport. It is vital not only to the national economy but also enables millions of citizens to keep in touch with their friends and family and to take a well-deserved holiday.

"The airport is currently operating at full capacity. A new runway at Heathrow will help secure jobs and underpin economic growth as we come out of recession. It is also entirely compatible with our carbon-reduction target, as demonstrated in the recent report by the Committee on Climate Change.

A transport department spokesman insisted officials had accepted during the hearings that they would take developments in climate change into account in the preparation of the national policy statement on the new runway, due in 2011. "BAA are still free to bring forward a planning application," he added.