Britain did not achieve the three per cent annual cut in carbon emissions needed to meet its first four carbon budgets, MPs have been told.
The independent committee on climate change's progress report found that emissions increased by three per cent last year.
It said the colder winter months were mostly responsible, but noted that even after adjusting for weather impacts, emissions had stagnated rather than fallen.
"The step change that we have previously highlighted has not yet been achieved," CCC chair Adair Turner said.
"It is crucial that government sets out detailed policies to support power sector decarbonisation and energy efficiency in homes and businesses. The successful implementation of these policies will determine our ability to meet carbon budgets."
Last year's emissions fell within the limits of the first carbon budgets, but Lord Turner said this was mainly due to the recession.
Shadow energy and climate secretary Meg Hillier said the report showed the coalition lacked a plan to meet Britain's climate change targets.
"As the CCC report proves, there has been little action in the last year," she commented.
"Ministers have rejected Labour's attempts to beef up the energy bill; Britain could have led the world on green design and technology.
"Instead, at a time when the government should be putting jobs first, Britain is slipping behind on low carbon jobs and manufacturing, and the chances of meeting our international obligations on climate change look ever-more remote."
Energy and climate change secretary Chris Huhne, responding to the report, said: "As we come out of recession the coalition's determined to reduce our reliance on fossil fuels which means a permanent shift to low carbon has to be locked into our economy in good times and bad.
"The coalition's once-in-a-generation reforms of the electricity market, the Green Deal and the Green Investment Bank shows we're serious about making the long term structural changes that are vital to cut emissions and keep the lights on."