The National Party has announced it would slow down the implementation of the Emissions Trading Scheme for some sectors.
National says New Zealand needs to carefully balance the cost of the scheme to households and businesses in difficult economic times.
At the moment, the transport, electricity and industrial sectors make payments on half their greenhouse gas emissions.
They were to face the full cost from 2013, but if re-elected National intends to give those sectors more time and push the date out to 2015.
National would phase in the move to full payments in three equal steps in January 2013, 2014 and 2015 as recommended by the ETS Review Panel earlier this year.
National Party leader John Key said the plan has a cost to the Crown and the way National will ensure it is fiscally neutral is to look at the second allocation of pre-1990 forest credits.
There would be a review in 2014 and agriculture would be included only if new technologies are available and more progress is made internationally on reducing greenhouse gas emissions.
The review panel which reported earlier this year recommended part-charges for the agriculture sector from 2015.
National would introduce legislation in 2012 to amend the scheme.
Labour leader Phil Goff said the decision would cost at least $500 million over four years and would change National's fiscal track completely.
"They're busy hacking into their revenue and betraying the promises they made to the world about New Zealand's commitment to curbing emissions of carbon and methane."
Mr Goff said National was quick to criticise others for not having a budget and challenged National to say where the money would come from.
Water quality
The slower phase-in period is part of National's environment policy, released on Wednesday, in which it also made a commitment to introduce a nationwide system to measure water quality.
The party's environment spokesperson, Nick Smith, says water quality is measured inconsistently throughout the country and National would introduce what he called the environmental equivalent of national standards in schools.
"That will enable us to actually rank which of our rivers is the cleanest, which is the dirtiest, which are getting better, which are getting worse.
"Our view is that transparency will actually help focus our minds on ensuring that we improve that fresh water quality."
Dr Smith says it's very frustrating at the moment as environmental groups produce one set of figures and the farming lobby another.
He says the Parliamentary Commissioner for the Environment would be responsible for auditing the data, as that office is independent of Parliament.
