Wales is expected to miss its own target for cutting greenhouse gas emissions by 2020, AMs have admitted.
Welsh Government ministers set a 10-year target in 2010 to slash emissions by 40% below levels of 1990. But by 2015, only a 19% drop has been reached.
The assembly's climate change committee report said Wales' industrial profile and cold winters should have been taken into account when the targets were set.
Chairman Mike Hedges said the targets had been "ambitious, but attainable".
A Welsh Government spokesman said it has "a longstanding commitment" to taking action.
In its Climate Change Strategy launched in 2010, it set a target of cutting emissions by 3% year-on-year from 2011, leading to an overall reduction of at least 40% below 1990 levels by 2020.
An extra target of an 80% reduction by 2050 was added by law in 2016, with ministers also required to set a series of 10-yearly interim targets by the end of 2018.
She said the resulting level of emissions varied year on year, depending largely on the impact of a small number of large installations.
New, lower emissions targets are now being set with advice from the UK Committee on Climate Change - a move AMs called "regrettable but necessary".
"The Welsh Government's targets on reducing greenhouse gas emissions in Wales were ambitious, but attainable," said Labour Swansea East AM Mr Hedges.
"That the Government will miss these targets by some margin is deeply disappointing, and the Committee is not convinced by some of the reasoning behind the failure."
Mr Hedges said the committee wanted a more co-ordinated approach across government departments and called for extra work in sectors such as agriculture, forestry, housing and transport.
The Welsh Government spokesman added: "We have consistently met our 3% policy target, which focused on emissions in devolved competence, but we recognised more needed to be done around our total emissions."
Aims include generating 70% of electricity from renewable sources and creating a carbon neutral public sector by 2030.
He said the government will consider the report.