Paul Melia: 'The hot topic: untangling the knot of how we tackle climate change'
Achieving consensus is difficult, never more so than when dealing with almost 200 different parties, all with different priorities.
But that is exactly what diplomats and negotiators will attempt to do at the UN climate talks which started yesterday in Katowice, a city in the heart of Poland's rust belt and home to one of Europe's largest coal producers.
The stakes are high. In 2015, almost 200 countries signed up to the Paris Climate Accord and pledged to reduce emissions and prevent catastrophic climate change.
But how that agreement, which comes into force in 2020, will work - and, crucially, how emissions cuts will be verified, which will be outlined in the so-called 'Paris Rulebook' - will be the subject of discussions running late into the night.
Decarbonisation will have a profound impact on places like Katowice, on Middle East oil producers and the US fracking industry, among others.
That said, the impacts of climate change will be felt globally, so rapid cuts are required, and time is running out.
There is also the vexed issue to be discussed of getting countries to ramp up their ambitions in cutting emissions.
Science tells us average global temperatures cannot rise more than 2C, and ideally no more than 1.5C, if catastrophic change is to be avoided.
As of now, national pledges - called nationally determined contributions (NDCs) - put the world on a warming path of more than 3C. That means greater ambition is needed. "Those are the two big-ticket items," one source said. "The review of the rulebook is the major one because it brings in action on finance, mitigation (reducing emissions) and technology transfer (giving developing countries the technology to cut emissions).
"The EU already has detailed reporting and accounting rules, but the rulebook should be applicable to everybody. Ideally it should be a common set of rules."
That poses its own challenges. While the European Union takes the approach of reducing emissions from all sectors, with outside verification from the Commission, other countries do things differently.
China, the world's largest emitter of greenhouse gases, doesn't talk about emissions cuts, it refers to carbon intensity. That means reducing emissions per unit of economic activity.
India, also a big emitter, takes a similar approach, with further complexity around creation of carbon sinks by planting forests to absorb emissions.
Others include 1990 as the reference year, meaning emissions will be cut by a certain date against the level of emissions in 1990, while others use 2005. "The rulebook is trying to capture all of them in a quantifiable manner," the source adds. "You should be able to come up with a statement at the end of, say, 10 years, and say how they have achieved reductions."
The trick with the Paris rulebook will be ensuring it is transparent, understandable and that, crucially, emissions reductions can be accurately measured and verified.
There are compelling reasons why this must happen. Global efforts are way off track, and emissions are rising again for the first time in four years. To meet the Paris goals, they must peak by 2020. As of now, that's not likely even by 2030.
In addition, greenhouse gas concentrations in the atmosphere continue to set new record highs, and the impacts are being felt - 2018 is on course to be the fourth hottest year on record. Twenty of the hottest years on record have been in the last 22 years. The climate is changing.
The second challenge for COP24 negotiators will be delivering a clear political signal to increase ambition. This is being facilitated under what's called the Talanoa Dialogue. Talanoa is a word used in Fiji and across the Pacific to reflect a process of inclusive and participatory dialogue, allowing wise decisions to be made for the collective good.
Three questions are asked: Where are we? Where do we want to go? How do we get there?
Almost 500 stories and 280 written inputs were submitted to the dialogue by governments, NGOs and other interest groups. These will be presented to politicians at the talks, called the 24th meeting of the Conference of the Parties (COP 24).
The Intergovernmental Panel on Climate Change (IPCC) report on achieving 1.5C is integral to guiding that process. Getting a rulebook will be crucial - if negotiations fail on this point, countries will not commit to greater action.
There are other issues too. Countries have committed to providing $100bn (€88bn) a year in climate finance for developing nations. The OECD says finance totalled $56.7bn (€50bn) last year, up from $48.5bn (€42.7bn) in 2016.
But given Donald Trump's attitude to climate change - he doesn't believe his own government's report on its likely impacts - it is a real concern that the US financial commitment will not be realised. What will that mean? Will others make up the shortfall? Will that gap be filled?
Politicians, including Climate Action Minister Richard Bruton, will travel to Poland this week, with sources suggesting the idea is to "rally the troops" at the start of the process, and give guidance to negotiators.
To highlight the extent of the challenge, it's notable that while the EU NDCs take into account all member states, there are divisions. Understandably, given its reliance on fossil fuels, Poland has deep concerns about rapid decarbonisation.
It's likely to seek a declaration on how to achieve cuts under a 'just transition' process - that means protecting workers in the fossil fuel industry. That could translate to calls for giving some countries a longer timeframe to decarbonise.
There will be no easy wins. But the science is very clear. The climate is warming, and how we heat our homes, fuel our transport and power our economies needs to change. That's a challenge not just for negotiations in Poland, but for us all.