In a major step against climate change around 200 countries accepted a legally binding deal to curb greenhouse gases used in refrigerators and air conditioners, a Rwandan official announced on Saturday.
The world's two biggest economies, the US and China, are part of the deal which divides countries into three groups with different deadlines to reduce the use of factory-made hydrofluorocarbon (HFC) gases.
"It's a monumental step forward," US Secretary of State John Kerry said as he left the talks in the Rwandan capital of Kigali late on Friday.
The pact calls for developed nations, much of Europe and the United States, to reduce their use of the gases gradually, with a 10 percent cut by 2019 and an 85 percent reduction by 2036.
— Patricia Espinosa C. (@PEspinosaC) October 15, 2016
Two groups of developing countries will freeze their use of the gases by either 2024 or 2028, and then gradually reduce their use. India, Iran, Iraq, Pakistan and the Gulf countries will meet the later deadline.
"Last year in Paris, we promised to keep the world safe from the worst effects of climate change. Today, we are following through on that promise," said UN Environment Chief Erik Solheim in a statement.
The deal introduces a wave of measures to help fight climate change. Last week, the 2015 Paris Agreement to curb climate-warming emissions passed its required threshold to enter into force after India, Canada and the European Parliament ratified it.
The Kigali deal, unlike the Paris agreement, is legally binding, has specific timetables and an agreement by rich countries to help emerging nations adapt their technology.
— REMA RWANDA (@REMA_Rwanda) October 15, 2016
The United Nations says phasing out HFCs will cost billions of dollars.
But scientists say the reduction of HFCs could be a major contribution to slowing climate change, avoiding perhaps 0.5 degrees Celsius (0.9 Fahrenheit) of a projected rise in average temperatures by 2100.
Reflecting increased demand from an expanding middle class in Asia, Latin America and Africa, environmental groups had called for an ambitious agreement on cutting HFCs to limit the damage from the roughly 1.6 billion new air conditioning units expected to come on stream by 2050.
The future is right here, today, in Kigali! A new milestone in mankind's ability to stand up to mankind's threats. pic.twitter.com/FJJXWmIIzY
— Busingye Johnston (@BusingyeJohns) October 15, 2016
The HFC talks build on the 1987 Montreal Protocol, which succeeded in phasing out the use of chlorofluorocarbons (CFCs), widely used at that time in refrigeration and aerosols.
The aim was to stop the depletion of the ozone layer, which shields the planet from ultraviolet rays which are linked to skin cancer and other conditions.