The State has downplayed the significance of the country's carbon reduction plan in addressing climate change, telling the Supreme Court that Ireland's emissions were "tiny" in a global context.
The move came in defence to a challenge by Friends of the Irish Environment (FIE) to the 2017 National Mitigation Plan.
FIE claims the plan is too vague and lacking in ambition to be of use.
As such, the group says the plan fails to comply with the 2015 Climate Act and breaches the rights to life and a healthy environment by allowing risks of sea level rise and altered weather.
On the second day of the two-day hearing, Eileen Barrington SC, representing the State, said FIE misunderstood the plan which was only a "first step" in national policy on carbon reduction which had an ultimate goal for achievement in 2050.
She said the group had conflated the science of climate change and the plan to make out that any failures by Ireland would bring about the described risks.
"Climate change is a global challenge. Ireland's emissions are a tiny proportion of the world's emissions," she said.
A second counsel for the State, Rory Mulcahy SC, said there was no evidence to suggest that measures in the plan would cause sea level rise or altered weather.
His stance prompted lengthy discussion with the seven judges. Judge Iseult O'Malley said she understood there was an assumption that how Ireland acted on climate mattered.
Mr Mulcahy replied that he was not saying Ireland's international obligations did not matter but Chief Justice Frank Clarke said there was a risk of him coming across like that. Mr Mulcahy insisted he was making a more "nuanced" point.
Earlier in the day, there was intense discussion as the judges sought clarity on whether or not Ireland was in breach of EU obligations on emissions.
Ms Barrington said while we were far behind on emissions cuts, Ireland was in compliance through buying carbon credits to make up the shortfall.
"There is compliance. As far as there are failures to meet EU obligations, it's only by way of emissions," she said.
Judge Clarke said the case was "important and difficult". A ruling is likely to take months.