In order for the accord to take effect, at least 55 countries responsible for 55 percent of global greenhouse gas emissions must complete the ratification process, Efe news reported.
At least 15 countries, mostly small island states, have already done so on Friday.
The two countries leading the world in emissions of greenhouse gases, the US and China, committed themselves on Friday to complete the ratification process this year.
The speeches by world leaders highlighted their sense of urgency about the need to stop global warming and go beyond the commitments of the Paris Agreement.
“Record global temperatures. Record ice loss. Record carbon levels in the atmosphere. We are in a race against time,” UN Secretary-General Ban Ki-moon said.
“Today (Friday) is a day for our children and grandchildren and all generations to come. Together, let us turn the aspirations of Paris into action. As you show by the very act of signing today, the power to build a better world is in your hands,” Ban said.
Illustrating that statement, Secretary of State John Kerry sealed the pact in the name of the US accompanied by his two-year-old granddaughter Isabelle who was sitting on his lap. He said his country “looks forward to formally joining this agreement this year”.
France was given the honour to sign the pact first, in recognisation of its hosting of the UN climate change conference in Paris in December 2015, which gave birth to the pact after nearly two weeks of tough negotiations.
The more than 60 leaders and hundreds of national representatives meeting in the chamber of the General Assembly listened to a strong speech by actor Leonardo DiCaprio, a UN Messenger of Peace on the subject of climate change.
“This is the only body that can do what is needed. You, sitting in this very hall. The world is now watching. You will either be lauded by future generations, or vilified by them,” he said.
Many leaders underscored the need to go far beyond what was established by the Paris Agreement, which among other measures set a worldwide commitment to keep the world’s average temperature increase well below the two degrees Celsius above pre-industrial levels and to pursue efforts to limit it to 1.5 degrees Celsius.
However, there remain quite a few obstacles for the achievement of this ambitious goal, particularly the divergence between developed and developing countries over thorny issues like funding, responsibility and technology transfer.
Scientists said the monthly global temperature record has kept being broken over the past 11 months, and that 2015 has become the planet’s warmest year since the late 19th century, Xinhua news agency reported.
Addressing the ceremony as a youth representative, 16-year-old Getrude Clement from Tanzania said: “As young people, the future is ours, but this is not the future we want for ourselves.”
After Friday, countries still have one year to ink the Paris Agreement, which remains open for signature till April 21, 2017.