HFCs. Ever heard of them? They are chilling your vegetables, cooling your office and keeping your hairdo in place.
Unfortunately hydrofluorocarbons, to give them their full name, are a timebomb for the climate. As demand for air conditioning surges, these manufactured gases could raise global temperatures by up to 0.5C this century.
Next week, national delegates meet in Kigali, the Rwandan capital, to try and agree a phase-out.
More than 100 countries including the US, EU and islands threatened by rising sea levels are pushing for an ambitious deal. Others like India and Gulf states fear the economic impacts of a swift transition.
Here's all you need to know about the coming battle.
A unit of HFC traps up to 23,000 times the heat of a unit of CO2, making these refrigerants much more dangerous than CO2 in the long run.
Scientists calculate that replacing them with greener alternatives could prevent global warming of 0.35-0.5C by 2100. It may not sound like much, but 0.5C was the heart of the debate towards a climate deal in Paris. Low-lying island states say the difference between 1.5C and 2C is a life or death matter.
HFCs were introduced relatively recently, to replace the the ozone-destroying chlorofluorocarbons (CFCs) banned under the Montreal Protocol in 1987. At the time, they provided a much needed alternative which allowed the ozone layer to repair itself.
Now, the plan is to repeat the trick for HFCs, using the same treaty. The small number of companies producing ozone-depleting gases helped to keep the process manageable in 1987. Observers believe that the same industry-driven process could happen this year in Kigali.
After the Paris Agreement, there is momentum for a deal. But political differences remain.
Prior to the meeting, a group of more than 100 countries proposed an early freeze date, which is meant to reduce the damage caused by the coolants by capping them in 2021 at the latest. The group includes the United States, the European Union, the 54 countries of the African continent, Argentina, Chile, Colombia and a few island states.
India is set on a much slower phase-out, with a 2031 freeze date. This means that the country can ramp up its HFC emissions for another 15 years.
Well, it's partly down to cost. India's scenario will cost €12 billion (US$13.4 billion), compared to 34 billion (US$38.1 billion) for the developed countries' proposal, the Delhi based think-tank Council on Energy, Environment and Water estimates.
More importantly, it is about market share. India is worried its chemicals industry will lose out to US companies like Honeywell and Chemours (previously DuPont) with bigger R&D budgets.
As always, finance and technical support will be key.
A group of philanthropists and donor countries has pledged US$80 million to help poorer countries replace HFCs and improve energy efficiency.
"The US are championing HFCs phase-out at a global level, and it's very important that they help make possible for developing nations to follow suit," says Avipsa Mahapatra, global climate campaign lead at EIA.
"My hope is that [the summit] is well attended and that we agree an ambitious amendment to the Montreal Protocol to phase out HFCs," Vincent Biruta, Rwanda's minister for natural resources, told Climate Home last month.