There is renewed criticism that efforts to combat greenhouse gas emissions in New Zealand are proving ineffective.
Carbon traders complain of falling costs payable under the emissions trading scheme by companies that pour greenhouse gases into the atmosphere.
Carbon credits are supposed to be worth enough to entice companies to clean up their act, but prices have dropped from $25 a tonne to $3 due to a gloomy world economy.
Roger Dickie, of the Kyoto Forestry Association, says the Government has also allowed low quality units from overseas, including Eastern Europe, into the Emissions Trading Scheme which no other country allows.
"The effect is that the price has plummeted to rock bottom so there is absolutely no incentive for sequesters like foresters to plant trees and there's actually no incentive for emitters to reduce their emissions."
Mr Dickie says low prices incentivise clear-felling of forests for profitable dairy farms because cheap carbon credits also mean low carbon charges for deforestation.
Legislation to amend the Emissions Trading Scheme is going through a Parliamentary select committee, where it has been criticised by the Parliamentary Commissioner for the Environment.
Jan Wright told MPs the bill would significantly weaken the scheme and shift 95% of the cost of emissions on to taxpayers who are already subsidising climate polluters.