Environment Minister Nick Smith wants officials to recalculate New Zealand's greenhouse gas emissions because they are likely to grow more slowly thanks to the global economic meltdown.
Dr Smith said the Government would not set short-term targets for reducing emissions until he had an accurate picture of what future emissions would be.
He wants the Ministry for the Environment to recalculate how much carbon dioxide and other greenhouse gases New Zealand will produce in the next four years, taking into account the recession.
The Government's goal is to cut greenhouse gas emissions to half 1990 levels by 2050.
National has not set any interim targets or outlined how it will meet its goal.
Under the Kyoto Protocol, New Zealand has four years to shave about 26 per cent off emissions, if it is to meet its obligation to pull them back to 1990 levels by 2012.
Current projections say we will overshoot that target by a quarter - leaving the country with a hefty bill for carbon credits to cover the shortfall.
But Dr Smith said those projections were based on assumptions about economic growth calculated before the recession hit. He said it was inevitable the rapidly changing economic environment would affect emissions.
The minister said he did not know when new figures would be available, because his focus had been on reforming the Resource Management Act.
Green Party co-leader Russel Norman said National's goal of a 50 per cent reduction by 2050 was meaningless without a set of interim targets.
He agreed the economic slowdown would probably cut emissions - perhaps by reducing transport or electricity use or growth in agriculture - but said that was no reason to delay.
"If as a result of the recession we get a quicker start on reducing our emissions which then we build on by actually building the sustainable infrastructure that we need, then what's the harm done? Why don't we set the targets now?"
The Green Party wants deeper cuts to emissions of closer to 80 per cent of 1990 levels by 2050.
National has undone several of Labour's climate change measures since coming to power late last year, including overturning a ban on incandescent lightbulbs, repealing a compulsory obligation for oil companies to sell biofuels and scrapping a ban on new coal- and gas-fired power stations.
It is reviewing the Emissions Trading Scheme (ETS) - the major plank in Labour's policy for reducing greenhouse gas emissions - but has not suspended it as stated in its confidence and money supply agreement with the Act Party.
A special select committee chaired by United Future leader Peter Dunne has been chosen to review climate change and the ETS.
In December, Dr Smith said it was unrealistic for New Zealand to be a leader of global efforts to reduce climate change when its emissions were growing at one of the fastest rates of any developed country.
Public submissions to the select committee close this Friday.