The Taoiseach's expected to commit €225 million a year by 2025 to help poorer countries with climate change.
Micheál Martin will make the pledge as part of an address to the Cop26 climate conference in Glasgow later.
But that won't be enough to tackle the issue, according DCU climate policy lecturer, Sadhbh O'Neill.
"She said none of that money is going to make a difference unless we reduce our emissions."
"It's quiet clear that developed countries will have to do the heavy lifting," she said.
The climate expert says "the real test of the Irish commitment" will be how we meet tackle the methane issue.
Leaders Agree To Reverse Deforestation
Meanwhile a deal has been done to end and reverse deforestation - the first big agreement to come from the summit.
Environment Minister George Eustice announces a new #COP26 deal which will see more than 100 leaders representing 85% of the world's forests commit to stopping and reversing deforestation by 2030.
— Sky News (@SkyNews) November 2, 2021
100 world leaders have made the commitment - covering 85-percent of the Earth's woodland - by 2030.
Brazil, China and Indonesia are among nations involved.