Chemicals in refrigeration and air conditioning are likely to be rapidly phased out if delegates can reach agreement. Around 150 countries are meeting to try and agree a ban on HFC gases. HFCs were introduced to limit damage to the ozone layer, but cause much greater levels of warming than CO2.
However nations are divided over the speed and timing of any phase-out. Concern over a growing hole in the ozone layer above Antarctica saw the Montreal Protocol agreed back in 1987.
The key aim was the removal of gases called chlorofluorocarbons (CFCs) which scientists had determined were causing the destruction of ozone, which protects people and animals from the dangerous impacts of ultraviolet radiation.
Found in hairsprays, refrigeration and air conditioning, CFCs were ultimately replaced by factory-made hydrofluorocarbons, which essentially do the same job but without the damage to the Earth’s protective layer.
Demand for air conditioning in India and other developing countries is booming. The substitution worked. Earlier this year, scientists said that the ozone hole is showing "the first fingerprints of healing."
There has been just one unfortunate side effect caused by the solution. HFCs are several thousand times better at retaining heat in the atmosphere than carbon dioxide. HFCs have helped the ozone layer, but exacerbated global warming.
A well being destructive, they are also the fastest growing gas – increasing demand for air conditioning in emerging economies has seen the use of HFCs up by 10-15% per year.
Scientists, through the Intergovernmental Panel on Climate Change (IPCC), have warned about the warming dangers of HFCs. Unusually, governments took heed and have sought an international approach to phase out all these chemicals.
This move has been given added urgency in the wake of the Paris climate agreement, which aims to keep temperature rises this century well below 2C and as close as possible to 1.5C.
The scale of HFC growth is adding greater urgency say experts. After a year of negotiations, an amendment to the Montreal Protocol to phase out these chemicals is expected to be agreed at this meeting in Kigali.
"It’s a big piece, these are the fastest growing greenhouse gases right now, although they are still a small percentage," said Durwood Zaelke, from the Institute for Government and Sustainable Development (IGSD).
"But an amendment could bend the curve down quickly and take out 100 billion tonnes of CO2 equivalent by mid century, and by the end of the century you’ll avoid up to half a degree of warming."