The Government has been warned that New Zealand could miss already modest targets for greenhouse gas reductions by the end of the decade.
The Government has pledged to cut emissions by 5% below 1990 levels by 2020.
That figure has been criticised by environmentalists as not being ambitious enough.
But the Sustainability Council has produced a cabinet paper showing New Zealand will miss even that moderate goal.
Executive director Simon Terry says it projects emissions to be 10% over 1990 levels by 2020.
He says the real figure could be even worse if forests planted since 1990 reach maturity and are harvested in large quantities.
"Remember that those trees are absorbing that carbon, they're planned to be cut down in the 2020s, and when that carbon is released again, the short term benefit is lost and the carbon needs to be paid back.
The new information follows a report from the Ministry for the Environment projecting big emissions rises by 2040.