Ireland has become the second country in the world to declare a climate emergency.
he decision was made on Thursday evening after an amendment to a parliamentary climate action report was agreed by both the Government and the opposition parties.
It comes as EU leaders put action on climate change at the top of the agenda in the next five years.
Climate Action Minister Richard Bruton said climate change has been "rightly" described as the greatest challenge facing humanity.
"We're reaching a tipping point in respect of climate deterioration," he said.
"Things will deteriorate very rapidly unless we move very swiftly and the window of opportunity to do that is fast closing."
He added that urgency had been injected into the debate by the protests by school students calling for action from parliaments around the world.
"It is justified that a level of urgency be injected into this debate," he said.
"When we speak of an emergency people often think of something unexpected that can be resolved through a sustained effort for a relatively short time. This is not an emergency of that sort. This is a much more challenging emergency in that we must change our behaviour in profound ways and do so on a sustained basis."
Chairwoman of the Oireachtas Climate Change committee Hildegarde Naughton welcomed the cross-party support in recognising the need for urgency and declaring a climate and biodiversity emergency.
She urged the Government to fast track legislative changes.
In a tweet she wrote: "Good news at the end of the Dail motion today supporting the report of the Climate Action Committee, which I chair. We now have cross party support in declaring a climate and biodiversity emergency. Action now needed."
Fianna Fail's climate action spokesman Timmy Dooley, who moved the amendment, said: "Unless we cut emissions significantly by 2030, the consequences will be dire.
"Biodiversity loss is an existential threat that is fundamentally linked to the climate crisis and Ireland's response is similarly lacking," he added.
He maintained that if the Government implemented the recommendations made in the committee's report it would allow the country to get back on track and "bring an end to our laggardly response to climate change".
Sinn Fein's Brian Stanley also called for a climate emergency to be declared.
He said: "Climate action should not be viewed as a burden. We should see it as an opportunity to create a stronger, more sustainable economy for everyone. To do that, however, we have no option but to radically transform our society and economy."
Green Party deputy leader Catherine Martin said young people realised that they will be the ones most affected by the "short-sightedness" of Government today.
"It is also essential that in declaring a climate emergency we commit to concrete, real and identifiable action rather than just uniting around vague concepts," she told the Dail.
"There is little value in all declaring a climate emergency without committing to doing anything about it."
Climate change campaigner Greta Thunberg, 16, who has led a movement of young people across Europe calling on leaders to take action, welcomed the declaration.
She tweeted: "Great news from Ireland!! Who is next?
"And remember: #ClimateEmergency means leaving fossil fuels in the ground."
Earlier this month the UK became the first country in the world to declare a climate emergency.