“We cannot fail in Katowice,” said UN Secretary-General António Guterres in the opening ceremony, on 3 December. A sentiment echoed by the President of COP24, Michał Kurtyka, who stated: “Without success in Katowice, there is no success in Paris.”

In the French capital, three years ago, countries agreed to do everything they could to keep global temperature rises to well under 2°C above pre-industrial levels, and as close as possible to 1.5°C.

Now, in Katowice, Poland – with 2018 chosen by the parties themselves as the deadline for the adoption of implementation guidelines or a “work programme” to move forward with – the 197 parties of the UN Climate Chance Convention (UNFCCC) are gathered to agree on how they will achieve the Paris commitments collectively, build trust among each nation, and bring the 2015 agreement to life.

“Some might say that it will be a difficult negotiation. I know it is not easy. It requires a firm political will for compromise,” said Mr. Guterres during the opening ceremony. “But, for me, what is really difficult is to be a fisherman in Kiribati seeing his country at risk of disappearing, or a farmer or herder in the Sahel losing livelihoods and losing peace. Or being a woman in Dominica or any other Caribbean nation, enduring hurricane after hurricane destroying everything in its path.”

Historically, multilateral climate negotiations have been difficult, as countries often attempt to protect their national interests, including economic ones.

That is why the commitments made in Paris were hailed as groundbreaking in many ways. In addition to the 2°C/1.5°C target, the deal included commitments to: ramp up financing for climate action, including financial support from industrialised nations to developing countries; develop national climate plans by 2020, with self-determined goals and targets; protect ecosystems, including forests; strengthen adaptation and reduce vulnerability to climate change.

Agreeing on how to make all of the above happen, is a politically and technically complex matter that sometimes conflicts with a variety of local realities, country categorisations, scientific questions, money issues, and ultimately, brings into question the ever-so complicated notion of trust among nations.

Here are five of the most major tension points:

1. A common goal, but different parties, different realities

The first point of tension here is that some countries feel the need for global action more acutely than others. Take the plight of small island nations, for example, and areas of extreme weather activity such as the Sahel or the Polar regions.

In addition, industrialized countries are considered to have benefitted for decades from an economy that had no limits on greenhouse gas emissions, and therefore, they should take the biggest responsibility when it comes to the global effort to reverse the trend.  But then again, others contend that some currently developing nations, now have record emissions and that climate action responsibility should lie with them to a greater extent.

The Paris Agreement achieved a delicate balance to bring all countries together. All countries, to varying degrees, have recognized that climate change is a global problem that requires a global response, and they have all showed the will to contribute to collective climate action efforts, as evidenced by the fact that 181 national climate action plans with self-determined targets have been submitted to the UN to date.

However, as countries face different realities, with various levels of economic and social development, the actions and obligations of the 197 parties need to be differentiated accordingly, especially when it comes to the financing of climate action – these are known as “common but differentiated responsibilities”. At COP24, a lot of the discussion centres around how to accommodate and handle these different realities fairly for all parties, while ensuring that the greatest and most ambitious climate action possible, can be undertaken.

2. Country categories

The Climate Change Convention, adopted in 1992, divides its 197 parties into two main groups: the industrialized group of 43 nations, and the developing group of 154, including 49 “least developed countries”.

The climate action contributions and responsibilities of each group differ with regards to how transparently and regularly they communicate their actions and provision of support; especially in terms of finance or technology-transfer, now, and in the long term.

Because the two groups were established more than 25 years ago, and taking into account that national socio-economic situations have evolved over time, some parties feel that the composition of these groups should be reassessed as we look to implement the Paris commitments. However, there is no process to change this grouping – and none is planned or anticipated - another complex point for this COP.

3. 'Welcoming' or 'noting' the science?

To facilitate the political discussions and ground them in fact, various scientific reports are being considered at COP24. One of them is last October’s landmark Special Report on Global Warming of 1.5˚C, prepared by the Intergovernmental Panel on Climate Change (IPCC), drawn up by hundreds of scientists from around the world. The report, commissioned as part of the Paris Agreement, states that limiting the rise in temperatures to 1.5°C by the end of the century compared to pre-industrial era, remains possible, but will require an “unprecedented” shift in every aspect of our societies.

While all countries acknowledge the need to tackle climate change, one of the debates here at the COP is whether the IPCC report should be officially “welcomed” or merely “noted.” This seemingly small language technicality raises a critical question: to what degree should policy be based on science? It also signals a difference on how urgently and intensely various countries want to engage in climate action moving forward.

4. The ever-so thorny question of financing

Climate action – which requires new technology, infrastructure and skills – represents a cost that some nations, especially the least developed and most vulnerable, cannot carry alone. In Paris, donor nations committed to mobilising $100 billion every year to fund climate action in developing countries, starting in 2020. This figure would include public and private contributions, which renders the reporting quite complex… Countries are arguing on how close we are to meeting that target and whether it will be met by 2020.

Another burning issue is the lack of clarity over what constitutes “climate finance”, as many countries report some of their “development aid” as “climate action aid”. This lack of clarity complicates the discussions considerably, and questions regarding reporting, transparency and accountability are on the table.

5. Guidelines for true trust among nations

All the countries recognize the need for guidelines to be in place, so they can move on to implementing the Paris Agreement, and they are all mindful of the 2018 deadline. However, if we are to course-correct fast and well, efforts and investments are required – including in economic transition, ambitious reductions in greenhouse gas emissions, technology exchange and knowledge-sharing.

What it all comes down to, is the ephemeral trust among nations, an important element that can only be realized if tangible transparency measures are in place.

“We have no time for limitless negotiations,” said UN Secretary General António Guterres. “A completed work programme will unleash the potential of the Paris Agreement. It will build trust and make clear that countries are serious about addressing climate change,” he stressed.

The conversations on reporting and evaluation, with the potential set-up of peer review systems, are very challenging.

The negotiations on all of these issues are meant to last until the end of the week.

“Many political divisions remain. Many issues still must be overcome,” said the head of the UNFCCC secretariat, Patricia Espinosa, as she launched the high-level segment on Tuesday.

“But I believe it’s within our grasp to finish the job,” she stated confidently to the dozens of decision-makers gathered together in the conference hall.