The government has been accused of “duping” people into believing it is taking the climate crisis seriously by increasing carbon tax.
Sinn Fein president Mary Lou McDonald described the tax hike as a “hoodwink” and a “ruse”.
As part of the Budget 2020 measures, the government has increased the carbon tax by six euro per tonne.
It came into effect at midnight on Wednesday for petrol and diesel while home-heating fuels will be impacted by May next year.
Finance Minister Paschal Donohoe said the tax hike will raise 90 million euro in 2020.
Sinn Fein has heavily criticised the decision, claiming it will “disproportionately” hit the vulnerable and low-wage workers.
Speaking during Leaders’ questions, Ms McDonald claimed the move will deepen poverty and inequality.
“It’ll make life harder for those families that are just about getting by,” she said.
Your carbon tax hike is not climate action, at best it might be called tinkering, or a half measureMary Lou McDonald
“This is not a climate action measure, it’s not about making Ireland greener or cleaner and it’s certainly not about changing people’s behaviour.
“In order for carbon taxes to influence behavioural change, they have to be supported by investment and we have all of the evidence of this fact here in Ireland.
“Your existing carbon tax has generated 400 million euros every year since 2015 without changing behaviour or government policy and critically, emissions aren’t dropping.
“This shows that you must provide people with alternatives for them to transition to a low carbon lifestyle.
“Presenting this regressive tax as a climate action measure is a hoodwink. It’s a ruse.
“It’s an attempt to dupe people into believing that your government is taking the climate crisis seriously, but nothing could be further from the truth.
“Your carbon tax hike is not climate action, at best it might be called tinkering, or a half measure.
“At worst, it’s another PR stunt, the bill for which you pass on to workers, on to families and to pensioners.”
She called for the government to fund climate action through “progressive taxation” and invest in transport, energy and infrastructure.
Taoiseach Leo Varadkar accused Ms McDonald of being “out of touch” with the facts.
“You’re out of touch when it comes to the enormous demand from people across Ireland, particularly younger people, in that we should actually take action when it comes to climate change,” Mr Varadkar said.
“I don’t think for a second that increasing any taxes is ever going to be popular or ever going to be welcomed, but sometimes is the right thing to do.
“On this occasion, it is the right thing to do and this is a tax which is all about the environment and climate action.”
He said the revenue will be ring-fenced to help the most vulnerable and those at risk of fuel poverty.
He claimed that the poorest households in Ireland will be “better off” because of the rise in carbon tax.
Ms McDonald, however, accused the Taoiseach of being a “green poser” who is not serious about climate action.
“But you are serious about hammering those families and workers who ought to have been given a break yesterday,” she added.
Mr Varadkar claimed that left-wing politics and populist politics is “anti-environment” and went on to accuse Sinn Fein of trying to hijack the green movement to promote a philosophy that is “profoundly anti-environment”.