The Government may have to pay up €150m for missing its greenhouse gas emissions target.
Ireland is currently 95% off meeting the target set for 2020.
Minister for the Environment Richard Bruton has revealed that the cost of missing the target to the taxpayer could be up to €150m, which is the cost of 'carbon credits' that the state will need to buy.
These help to offset the environmental impact of greenhouse gases by funding projects that reduce emissions such as restoring forests and making transport systems more energy efficient.
Minister Bruton said the figure could have been higher.
He said: "The expectation will be about 16 million tonnes and we will have to purchase them at the going price.
"We are in the fortunate position that we have acquired some of them, so we won't be paying the top current price."
The news comes after a climate emergency was declared last week.
Independent Energy Expert Marie Donnelly said people need to take action, not just the Government.
Ms Donnelly said: "At the end of the day if you live in, let's say a three-bedroom semi-detached, you're the person making the choice about your heating system, you're the person making the choice about whether your house is insulated or not."
The Government's latest climate action plan will be published in the coming weeks.