Former president Mary Robinson has said a lack of ambition at COP26 means that anyone under the age of 60 is likely to inhabit a world that is less livable in and facing extreme weather events, while anyone under 30 is "sure to live in that world".
On Saturday, nearly 200 nations reached a deal to combat climate change after two weeks of negotiations in Glasgow.
However, scientists and environmentalists said the agreement fell short of what was needed to contain dangerous temperature rises.
They also accused rich countries of not delivering much-needed finance to vulnerable states at risk of drought, rising seas, fire and storms.
Ms Robinson, who is chair of The Elders and former UN high commissioner for human rights said that presidents of small island countries will have gone home from COP26 "almost in despair" because they are barely just being kept alive.
Speaking on RTÉ's Morning Ireland, Ms Robinson said big emitter countries – US, Australia, China, Mexico and Brazil - did not increase ambition, while there was also a lack of ambition on the financial side.
However, she said that progress was made in a range of areas, including commitment to finance to help poorer countries adapt to the shocks of climate change, a pledge on methane and a push to reduce coal usage.
Former President Mary Robinson on 'a shameful dereliction of duty' at COP26. pic.twitter.com/njKUH2KZwK— RTÉ News (@rtenews) November 15, 2021
In addition, she said, there were commitments on oil and gas and a reversing of deforestation.
You need the complexities and the voices of the most vulnerable at the COP, she said, to impress upon those who do not have a crisis mindset.
However, she warned that the world is in more crisis mode and that was felt in Glasgow, and she said what will make the difference now is what happens on a local level.
The pact for the first time includes language that asks countries to reduce their reliance on coal and roll back fossil fuel subsidies, moves that would target the energy sources that scientists say are the primary drivers of manmade climate change.
Ms Robinson said that it is significant that for the first time the agreement reached at COP did include language on phasing out fossil fuels in the text.
She said that governments, including the Irish Government, need to invest to "make the move to green" and to make green jobs affordable .
Ms Robinson said that the fossil fuel lobby has always been very powerful, in particular Saudi Arabia, which she said "always claims a bad gain at COP" and seeks to remove language on youth, human rights, indigenous people and just transition.
Fossil fuel subsidies
Ms Robinson said fossil fuel subsidies fall into two categories.
The first is a subsidy that grants tax exemption to companies that produce fossil fuels, meaning that "we tax exempt what is killing us, would you believe it?"
She said that real thought and sensitivity is needed in removing the second type of subsidy, on the consumption of fossil fuels.
"Removing those ... can put people into energy poverty or real poverty and need to be done sensitively," Ms Robinson said
She added that the Government needs to invest in and make sure we can afford to go green in a way that brings people with us and [also] to have regenerative agriculture, which she described as "exciting".
Meanwhile, the chair of the Marine Ecosystems Protected Areas environmental group for seven Caribbean nations said local people must have a voice in decision making processes to tackle climate change.
Ruth Spencer said this was the final time for action and the voices of the local people are important in coming up with solutions that will work.
Speaking on the same programme, he said governments must be held accountable to ensure that a damage fund to mimimise the effects of climate change reaches those on the frontline of the crisis.
Ms Spencer said: "I want to hold everybody accountable. We at the local level, we have to get it right.
"When we go to ask for funding upon, then we should have the evidence. We should show the impact on people. The impacts on our ecosystems, our farmers, our oceans, we have to have it right. This is the final time for action."
RTÉ provides a daily update from Eirgrid on what fuel sources are powering Ireland's electricity system. It can be viewed here