The historic Paris Agreement on climate change became an international treaty on Friday, up to five years earlier than planned after countries ratified the document with “lightning speed”.
It comes just a few days before the start of the global climate summit in Marrakesh, Morocco, which has been dubbed the “conference of action” after the promises and arguably optimistic talk to limiting global warming to close to 1.5 degrees Celsius in France last year.
Experts said the swift adoption of the treaty showed the world was moving away from fossil fuels towards a low-carbon future.
While the European Union has ratified the treaty, the UK has not done so as an individual nation, although it has promised this will happen.
The accord became official after 55 nations accounting for more than 55 percent of greenhouse gas emissions approved it and is now binding on the signatories.
Previously it was thought this process might take until 2020, but progress has been swift in a sign that more countries are taking the dangers posed by climate change seriously.
United Nations' climate chief Patricia Espinosa said in a statement: “This is a moment to celebrate. It is also a moment to look ahead with sober assessment and renewed will over the task ahead.
“In a short time — and certainly in the next 15 years — we need to see unprecedented reductions in greenhouse gas emissions and unequalled efforts to build societies that can resist rising climate impacts.”
The Earth’s average surface temperature has risen by about 1 degree Celsius since the 1880s but a report by the UN Environment Programme this week calculated it is currently on course to increase by 3.4 degrees by 2100.
This would take the climate into dangerous territory where various tipping points, such as the release of vast amounts of methane currently frozen in the northern tundra, could create runaway warming conditions.
Li Shuo, global policy advisor at Greenpeace China, hailed the ratification of the Paris Agreement, but said it was now time for action.
"The lightning speed of the entry into force of the Paris Agreement is unprecedented and commendable,” he said.
“Marrakesh is when the rubber hits the road. This [summit] must turn the Paris vision into action.”
And Anthony Hobley, chief executive of the Carbon Tracker Initiative, said fossil fuel companies and investors should take note of the significance of the shift in the political wind.
"Ratification of the Paris Accord in record time shows there is no stopping the energy transition underway and signals the world’s ambition to decarbonize the world economy in the second half of the century,” he said.
"The writing is on the wall: National climate change commitments, rapid advances in clean technology, falling renewables costs and energy efficiency measures combine to significantly reduce demand for fossil fuels in next 20 years — a perfect storm for energy incumbents on the horizon.
"Despite this clear direction of travel stakeholders are still misreading the pace of change. Fossil fuel companies are ignoring the fundamental risk the ‘carbon bubble’ poses and clinging to orthodox growth strategies.”
Lord Adair Turner, a former director-general of the Confederation of British Industry and ex-chairman of the Committee on Climate Change, said: “The Paris agreement confirms that most major economies are now taking steps towards low-carbon economies.
“But the challenge facing all governments as they convene for the UN climate summit next week is that, despite increasing progress, emissions are not falling fast enough to fulfil the pledge made at Paris to keep global warming well below 2 degrees Celsius.”
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