Climate treaty is ratified by 170 nations
A total of 170 countries have ratified the Paris climate agreement at the United Nations headquarters in New York, paving the way for a low-carbon future.
The ratification of the Paris Accord means that nations will now take concrete steps to reduce emissions and hold global warming to no more than 2C.
The number of countries that signed is a record for an international treaty.
The agreement was negotiated and adopted by 196 nations that are party to the UN Framework Convention on Climate Change in Paris last December.
It commits them to cutting emissions from power generation, housing, transport and agriculture to help prevent dangerous climate change.
Acting Environment Minister Alan Kelly signed on behalf of Ireland, and said it sent an "unequivocal message" to businesses and citizens that world governments are committed to tackling global warming.
Countries must now set out national policies detailing how emissions will be cut, and the plans are expected to be completed in Ireland later this year.
The agreement will not come into effect until it is ratified by the countries which account for at least 55pc of the world's emissions.
The world's biggest emitters, the US and China, have previously indicated they would ratify the agreement this year, with a view to bringing it into effect as soon as possible.
Speaking at the opening ceremony in New York, UN Secretary-General Ban Ki-moon said the agreement "will shape the lives of all future generations in a profound way". Mr Ban urged all countries to pass the agreement.
The agreement was signed as the world marked the 46th Earth Day, and after 2015 was officially recorded as being the warmest year on record.
President Michael D Higgins yesterday spoke of the "inescapable necessity" of uniting in efforts to fight climate change.
"Should the current path of global warming remain unchanged, the prospects of human life are so dreadful that to evoke them would be to describe the nightmares of mass hunger, massive population displacement, increased violence and conflict," he said at the All Ireland-US Sister Cities Summit.