The UK will fail to meet its targets to cut greenhouse gases over the next decade without stronger and more ambitious policies, the Government's climate advisers have warned.
The Committee on Climate Change highlighted failures in policies such as improving the energy efficiency of homes, where the instalment of insulation has plummeted since new schemes were introduced last year.
Under current rates of progress, the country is set to cut its emissions by around 21% to 23% between 2013 and 2025, well short of the 31% set out in the "carbon budgets" for managing greenhouse gas reductions, a report from the committee said.
Committee chairman Lord Deben warned the UK was not on track to meet its legally-binding target to cut greenhouse gases by 80% by 2050, and the longer the country left tackling its emissions, the more expensive it would become.
Lord Deben said: "Climate change demands urgent action. We have started on the road and we are being joined by much of the rest of the world.
"However, despite our success, the UK is still not on track to meet our statutory commitment to cut emissions by 80%.
"The longer we leave it, the costlier it becomes.
"This report shows the best and most cost-effective ways to ensure we meet our targets. There is no time to lose."
In its sixth annual progress report to Parliament, the Committee on Climate Change said the first five-year carbon budget from 2008 to 2012 had been met as a result of policies and the impact of the recession.
Progress has been made in driving down emissions in a number of areas, including improving the energy efficiency of cars and developing wind power projects, the report said.
But in other areas, policies - which have been designed to deliver emissions cuts up to 2020 - need to be strengthened and made more ambitious in order to meet the goal for 2025.
Previous research by the committee has shown that the UK could save £100 billion in taking early action to drive down emissions.
The latest report found the number of homes being insulated plummeted after the new green deal and the Energy Company Obligation (ECO) schemes were introduced last year, with over 600,000 cavity walls insulated in 2012 but only 170,000 in 2013.
The committee said ECO, which requires energy companies to install energy efficiency measures in poor and vulnerable homes, was being redesigned to improve it.
But levels of ambition for the scheme remained low and should be increased.
The uptake of heat pumps, which are a low-carbon alternative to boilers, has been very low despite generous incentives for the technology.
Acting chief executive of the committee Adrian Gault said there were financial and non-financial barriers to introducing heat pumps, but high uptake in countries such as France and Switzerland showed they could be overcome.
"There's not a lot of awareness amongst householders on heat pumps, and the Government could work with the industry on increasing awareness," he said.
He also said the renewable heat incentive scheme should be extended past 2016 to boost the industry, and should be included in the green deal energy efficiency scheme for households to increase heat pump installations.
Government policy on the power sector had focused on the action that needed to be taken up to 2020, and there was a high degree of uncertainty about levels of support for low-carbon schemes after that date, the progress report warned.
The committee reiterated its call for ministers to set a target to slash emissions from the power sector by 2030 to give the industry the certainty it needed to invest in low-carbon energy.
The report, which graded progress in a number of areas on a traffic light system, gave a red light to technology to capture carbon from power stations and store it permanently underground.
There had been a five-year delay in getting the first projects off the ground, although two plants should be working by 2020, it said.
There were also far fewer electric vehicles on the roads than the committee had predicted, although the advisers said their previous estimates had been over-ambitious. he Government should back an ambitious European Union target for reducing emissions from cars in 2030, which would help drive forward the electric vehicle industry, the report urged.
A spokesman for the Department of Energy and Climate Change said: "The Government has met its first Carbon Budget, with emissions now 23.6% lower than in 1990 and renewables producing 15% of all electricity generation.
"We are on track to meet the next two carbon budgets set until 2022 and are pleased the committee recognises the good progress that has been made in many areas."
Paul King, chief executive of the UK Green Building Council, said: "While Government has clearly made good progress on some of its efforts to cut carbon, the committee exposes the lack of headway on energy efficiency within our buildings, and in particular, an unravelling of the previous good work on home energy efficiency.
"This is ironic, given that carbon reduction in buildings is not only the most cost-effective way of tacking climate change, but it also protects both households and businesses from soaring energy bills.
"Time is running out for the current Government to grasp this and to deliver on crucial policy areas such as zero-carbon homes and minimum energy performance standards in commercial buildings."
Friends of the Earth senior climate change campaigner Simon Bullock said: "The committee rightly warns that Government climate plans are way off course.
"The wettest winter on record should be a wake-up call that the impacts of climate change are already battering Britain, and without tougher action they will only get worse.
"Slashing carbon emissions offers huge opportunities for British jobs and business, through investment in low-carbon technologies and infrastructure.
"And reversing the shocking slowdown in progress on energy efficiency will cut people's fuel bills.
"The Government says it's committed to tackling climate change - but when it comes to taking action ministers appear to be sleeping at the helm."