Talks on phasing out a set of potent greenhouse gases used in fridges and air conditioning units are closer to success than ever before, say observers at a UN meeting in Vienna.
US secretary of state John Kerry and US environment chief Gina McCarthy arrive in the Austrian capital this week, among 40 ministers set to attend the Montreal Protocol negotiations.
At stake is 0.5C of global warming: that’s the projected boost continued use of these gases – known as HFCs – is likely to have on temperatures already drawing clear of 1C above pre-industrial levels.
“I’m pretty optimistic, we’ve had very good discussions,” said Steve Seidel, senior advisor at the Washington DC think tank C2ES and former manager of the EPA’s Stratospheric Protection programme.
“Till the  Paris climate agreement there were some parties who had held back… but now we find every country is in a spirit of ‘let’s get this done’,” said David Doniger, head of US NGO NRDC’s climate and clean air programme.
Finance to help countries use different types of coolants, access to the latest technology and agreement on phase-out deadlines are among key issues being debated by the Protocol’s 197 members.
By Saturday, UN officials hope to have the basis of a deal they can take to Kigali, Rwanda in October, where the final agreement is scheduled to be signed-off.
“This is the single largest piece of climate mitigation available in 2016,” said Durwood Zaelke, President of the Institute for Governance & Sustainable Development (IGSD).
“We started this campaign about 10 years ago… the sooner you get this done the better it is,” said Avipsa Mahapatra from the Environmental Investigation Agency (EIA).
“Avoiding that half-degree is crucial for limiting global temperature rise to below 2 degrees centigrade and avoiding the most severe impacts of climate change,” McCarthy wrote on a US government blog published this week.
HFC use is widespread and growing fast. Replacements for the ozone-busting HCFCs, their use in the US alone rose 77% from 1990 to 2014.
According to the US Energy Information Agency, without action HFC emissions are likely to soar 141% from 2005 to 2020 as demand for fridges and air conditioning rockets.
It’s a massive issue for efforts to tackle climate change. The warming potential of carbon dioxide is one. The 19 HFC gases have a global warming potential ranging from 4 to 12,400.
In a world already warming due to emissions from oil, gas and coal, demand for technology to cool buildings and food is expected to rise.
700 million air conditioning units are due to be installed by 2030 and 1.6 billion by 2050, the Lawrence Berkley National Laboratory predicted in October 2015.
Sales in India, Brazil and Indonesia are growing at a rate of 10-15% a year, it added. In India air conditioning can account for 60% of electricity demand on a hot summer day.
“If the world were to move to 30% more efficient air conditioning they could save enough energy by 2030 to avoid building up to 1600 medium sized power plants, and by 2050 up to 2500 medium sized peak power plants,” said Zaelke.
The cost to developing countries of switching to non-HFC coolant gases is the major issue at the Vienna talks, say observers.
The Montreal Protocol operates a fund to help countries adopt new technologies. Since the early 1990s it has spent around US$3.2 billion helping countries ditch ozone-killing practices.
A recent report by the influential Delhi-based Centre for Science and Environment think tank put the potential cost of switching from just one HFC variant at $1 billion a year to India, depending on how much access to new technology the country was offered.
“There’s a major concern on the part of India and China that the technology is available and at a reasonable price,” said Seidel.
“I think those concerns are being addressed, and what we’re seeing as these technologies are being adopted is the costs and effectiveness are improving in the near term.”
Assurances from wealthy countries to the developing world have been offered on cash said Clare Perry, who follows these talks with Mahapatra for the EIA.
But no specific numbers have been mentioned because countries are still discussing what the deadline for a phasedown should be.
“Assessment panels have made some calculations based on a couple of scenarios… at least through to 2030 it’s $2.5bn if they do the fast scenario…. $3.7bn if you do a slower phasedown,” she said.
“But you would not get a [full] commitment to that $2.5 billion – just a commitment every 3 years.”
All observers Climate Home has spoken to stress the UN is not writing a new treaty along the lines of the Paris climate deal; instead this is about amending the Montreal Protocol to tackle HFCs.
The intervention from the latter group – which includes the Marshall Islands, Kiribati and the Solomon Islands – is new, an indication the talks are assuming increased importance.
Their proposal calls for developed and developing countries to cut HFC use 55% by 2030. By 2033 richer nations should have cut their use 90%.
In contrast, India proposes developing countries only start phasing out HFCs by the end of next decade, with a full cut not until 2050.
Working out a compromise between these divergent positions is one of the major challenges facing negotiators, balancing the needs of science with political realities.
“A key challenge will be to find a flexibility… some countries are already using a lot of HFCs,” said Perry.
Still, significant obstacles have already been overcome during talks through 2016.
Given the Gulf region’s fearsome heat and doubts over the effectiveness of HFC replacements in some climates, Saudi Arabia argued for exemptions.
“Their primary concern has been addressed,” said Seidel, a decision which will allow Riyadh and other governments certain flexibility on ditching some of the 19 HFC gases.
If that minor win has allowed Gulf nations space to participate, so too has intensive US diplomacy with China, India, Brazil and South Africa.
President Barack Obama has raised HFCs in talks with Xi Jinping and Narendra Modi, political engagement observers in Vienna say changed the dynamics of the talks.
“[Saudi] King Salman and Obama have also reached an understanding on this,” said Zaelke.
“Some wanted to see how Paris played out and now the Paris Agreement is set in stone a lot of those concerns have fallen by the wayside,” added Seidel.
Few believe a Donald Trump presidency would bother with HFC regulations, adding to the urgency. “They are bringing out all the guns to bring this home,” said Zaelke of the State Department.
— Climate Home (@ClimateHome) July 21, 2016
As with all complex UN talks, a sense of a final package will likely only emerge in the closing hours of October’s Kigali meet, when key players feel their demands have been met.
For India and China this will revolve around finance, baselines and technology transfer. The US and EU want transparency and spy opportunities for their chemical industries.
With less of an economic interest in the talks, small island states will focus on the environmental integrity of an agreement.
Behind the scenes a loitering swarm of lobbyists are also flexing muscles, said observers, with representatives from chemical giants Dycon, Honeywell, Dupont and Mexichem in Vienna.
Success will mean a deal that all can present as a win-win to voters, customers and scientists.
“India will experience high growth in the air conditioning sector – but there’s an opportunity here to switch to the next generation of energy efficient units,” said Seidel.
“My hope is by end of this week they are pretty far along with a text they can frame key political decisions that minsters will have to make,” said Doniger.
With nerves fraying and tension rising, the #HFCphasedown twitter hashtag could be in for a punishing 48 hours: many negotiators are already complaining of tiredness and bad food.
Mahapatra has limited sympathy, given the need for a deal. “I understand the need for rest, food and not working 20 hour days but it is urgent… there are less than 5 years to stay under 1.5C,” she said.