The upcoming UN climate talks in Katowice, Poland, are the most important negotiation appointment since COP21 in France, when countries came together to build the Paris Agreement. This year, delegates hope to leave the meeting with a "rulebook" in place, a set of shared guidelines that will help individual countries implement their climate goals and compare their progress with others.

But today's geopolitical landscape is very different from the one that generated the visionary Paris deal, and presents an array of new challenges that the climate community could not have anticipated back in 2015.

"It's a very sobering moment," says Rachel Cleetus, leader of the Climate and Energy program at the Union of Concerned Scientists. In Paris, the world had envisaged much faster progress in the lead-up to this year's COP24. "We would now be going to Katowice with some renewed results, countries would put new emission targets on the table" Cleetus says, "and instead we are going into this meeting with a great deal of concern." She hopes that China and the EU will step up to fill the leadership vacuum left by the US, and show that "the Paris Agreement was more than words and countries are taking the [latest] IPCC report seriously".

Ahead of a COP that is being hosted by a heavily coal-reliant member country, the EU is showing its commitment with a €5 billion fund to help fossil-fuel dependent regions wean off carbon. Despite heated debates over coal reduction in poor regions and renewable tariffs, the EU will enter the talks with its climate goals within reach. Meanwhile, at a global level, the path towards decarbonisation looks much more uncertain.

The recent election of Jair Bolsonaro as new president of Brazil is the latest sign that the international community is increasingly split over climate change and the environment. The president-elect ran on an anti-environment platform and promised to roll back protection of forest and indigenous land. And while Brazil, whose congress ratified the Paris Agreement almost unanimously, is unlikely to follow the US example and abandon the deal, a change at the helm may mean that it won’t deliver on its targets.

This would be disastrous for the planet, as protection of the Amazon can make or break the Paris Agreement as a whole. Recent studies found that tropical forests are already so degraded that they are turning into sources of carbon, while deforestation remains on the rise. "If everything Bolsonaro has promised so far was implemented, the annual rate of deforestation could triple in four years’ time; it would be a disaster," says Carlos Rittl, executive secretary of the Brazilian think tank Climate Observatory.

Bolsonaro has recently appointed diplomat Ernesto Araújo as his new foreign minister. He believes that climate science is dogmatic and that environmental concerns are part of a ploy to spread a “globalist ideology.”  In many areas, according to Rittl, Bolsonaro is trying to replicate President Trump's approach to foreign policy, not only when it comes to climate diplomacy, but on trade relations with China, for example. "But Brazil is not the US, and it doesn't dominate the markets the same way." For example, with higher deforestation "the reputation of Brazilian companies trying to play a role on the international market would be at stake," he says. "Brazil is a commodity exporter and trade is an area that could put us back on track on climate and environmental responsibility." Rittl explains that the EU is a key partner for Brazilian exporters, and "they are not going to trade with a country that doesn't have the right sustainability standards. Same goes for China."

Brazil's situation could become an example of the power of trade as a tool for climate action. But it could also be a testament to the resilience of the Paris Agreement as a diplomatic framework, according to Karsten Neuhoff, head of Climate Policy at the German Institute for Economic Research. Despite the important leadership shakeups that have occurred over the past three years, "we are lucky to have the Paris architecture in place, which was envisaged to be resilient to behaviour of individual countries." This is because the deal is moving away from "negotiated global targets that all countries had to sign up to, to a system that makes countries responsible for their own targets" and is not weakened by deviations of individual countries, Neuhoff says.

An effective rulebook should ensure that this flexibility is maintained, while also offering a clear structure for countries to compare and take stock of their progress. This will happen every five years until 2050, when the world is expected to reach net-zero emissions. And while the Paris Agreement was designed to absorb the shock of potential pull-outs, the rulebook will tackle the problem of lack of compliance within the system. It will also assist countries that fail to submit their climate plans and identify potential systemic issues within a single country while avoiding punitive measures.

This facilitative approach echoes the success of the Montreal Protocol, which helped bring down ozone-depleting gases with an unmatched record of compliance. It is this success that the UN hopes can be replicated at COP24.

Disclaimer: The views expressed in this article are personal.