The government has insisted it is on track to meet and exceed its Kyoto target, as new figures show greenhouse gas emissions fell between 2004 and 2005.
Environment secretary David Miliband said the 0.1 per cent drop over the year meant Britain was now emitting 15.3 per cent fewer emissions than in 1990, which is already in excess of the Kyoto protocol target of 12.5 per cent by 2012.
If the effects of the European emissions trading scheme (ETS) - which gives industries pollution credits to use or sell - are included, this reduction would be 23.6 per cent.
However, much of this reduction is due to a 4.6 per cent reduction in the amount of carbon produced by households in Britain, and emissions from air travel - which are not included in the Kyoto target or the ETS - have actually gone up substantially.
The figures from the Department for Environment, Food and Rural Affairs (Defra) reveal an increase of 7.1 per cent for domestic flights and 5.7 per cent for international flights.
Shadow environment secretary Peter Ainsworth warned: "The government's 'predict
and provide' policy on aviation and airport expansion is clearly inconsistent with its rhetoric on climate change."
Mr Miliband acknowledged the rise, but said it was the "strongest evidence yet" that aviation needed to be brought into the ETS. He also pointed to the fall in household emissions as proof that government policies were beginning to have an effect.
But the Liberal Democrats suggested this was more because people were responding to higher energy prices, and said the overall cut in emissions was because of a shift from coal to gas power stations, "which this government cannot claim credit for".
Mr Miliband admitted the government's own target of cutting emissions by 20 per cent looked "increasingly difficult to achieve".
But he said: "The 2010 goal was always designed to be stretching. We are making definite progress towards it, and the projected 16.2 per cent reduction is testimony to that progress.
"However, the CO2 emission figures make it very clear that we need to do much more to cut emissions, and this is why the climate change bill, announced in the Queen's speech, will be essential to those efforts."
The bill would put into law the government's long-term goal to cut carbon dioxide emissions by 60 per cent by 2050, and set out how it could be achieved. But it will not include annual targets on cutting emissions, which opposition parties are calling for.
Mr Ainsworth commented: "David Miliband has said that binding annual emissions targets are 'silly' because emissions will naturally rise if 'the weather is bad in one year.'
"However, 2005 was one of the warmest years on record for the UK - and yet overall UK emissions only fell by a measly 0.1 per cent.
"It is clear that 'the weather' is not to blame for the UK's increasingly embarrassing emission reductions record: Labour's indifference and inaction are the problem."