The little-known talks, which take place each year ahead of the United Nations landmark COP climate summits, lay the groundwork for humanity's response to global warming. Negotiators from across the world will agree on technical details about how to cut pollution, protect people from a hotter and more hostile environment and move money to pay for it. It will clear the way for bigger political fights at the COP28 conference in the United Arab Emirates in November.
The meeting in Bonn gives officials a space both to talk about the outcome of the last climate summit and figure out what is and what's not working in their climate policy, said Alex Scott, a diplomacy expert at the climate think tank E3G in London. "The thing that's different about Bonn is that the politicians aren't there — or very few of them are."
Paying for climate damage, cutting fossil fuel pollution
The Bonn conference is the first time climate diplomats will have come together since COP27 — a tense summit in Egypt late last year where world leaders agreed to set up a fund to pay poor countries for some of the damage wrought by extreme weather. The last-minute deal was a landmark step in rich countries taking responsibility for their carbon pollution.
But many countries were left frustrated by the weak decisions on climate mitigation — actions to cut planet-heating emissions — that came out of the summit.
"We got agreement on the new fund," said Marjo Nummelin, Finland's lead climate negotiator. "But we really do think that that we cannot have another COP where there is no real progress on the mitigation agenda."
Even the fund's future is uncertain. Before any money changes hands, countries will have to agree who will pay, who will get the money, how much will be sent and under which circumstances. Some of the work for that will start in Bonn, but the political arguments will be left until later this year.
"My expectation out of Bonn is that at least we are going to have an informal note," said Juan Carlos Monterrey, a former chief climate negotiator for Panama who now works for Geoversity, an educational charity trying to save wildlife. "And an informal note is literally — as it sounds — just a note with no standing that collects the vision, the positions of the different parties and groups."
For some countries on the front lines of climate change, battling scorching heat waves and watching homes wash away as sea levels rise, fixing those issues on paper is no guarantee of cash.
Rich countries broke a promise made in 2009 to get poor ones $100 billion a year in grants and loans by 2020. Unlike the new fund, which will help countries recover from disasters, this money was supposed to help them cut carbon pollution and adapt to extreme weather.
Some analysts expect they will hit the target in 2023, three years later than planned, though data to check this will only be available in the following years. In any case, scientists have said, the money promised was never enough to begin with.
Negotiators in Bonn will discuss a new climate finance target for after 2025.
Rising emissions a 'death sentence'
The UN will also check progress toward climate goals during the conference in Bonn. Its global stocktake, a two-year review of humanity's response to climate change, will move into its final phase in Bonn this month before being published ahead of COP28 in November.
The review will draw on previous research that has found countries are spewing too much planet-heating gas for world leaders to honor their climate promises, and spending too little money to keep their citizens safe from extreme weather.
"There has to come a point where we reduce emissions, because otherwise for countries like us it's really a death sentence," said Khadeeja Naseem, climate minister for the Maldives, an island nation in the Indian Ocean.
"That's just not for the dramatic value," she added. "The Maldives is just a meter above sea level and all of its critical infrastructure is just 100 meters from the shore. We have increasing erosion. Tidal swells in most homes. And we're a geographically dispersed island nation. There is a lot at stake here."
In a bid to stop heat waves getting hotter and coastal floods stronger, world leaders promised in 2015 to try to limit global warming to 1.5 degrees Celsius (2.7°F) above pre-industrial temperatures by the end of the century. But their current policies are set to nearly double that temperature increase.
To meet their targets, scientists have said, world leaders must immediately burn less coal, oil and gas — and make deep and rapid cuts to emissions in all sectors. Governments will put forward new and more ambitious action plans at the COP30 conference in 2025, which will take place in the city of Belem near the Amazon rainforest, according to a recent announcement by the Brazilian government.
"For us, it's absolutely critical that there is an international enabling environment that will guide parties to put on the table the most ambitious action," said a Brazilian climate negotiator who agreed to speak to DW under the condition of anonymity. If the gaps in ambition aren't closed by then, and not implemented during this critical decade, "it means that we lost the fight for 1.5 C."
Oil and gas lobbying overshadow COP28
The COP28 climate summit has been criticized because its president, Sultan al-Jaber, is the head of UAE oil company ADNOC. In an open letter published in May, 130 lawmakers from the European Union and United States called for his removal.
"With that appointment, you are just sending the message that the oil industry is in charge," said Monterrey, the former negotiator from Panama. "We are at a higher risk than before of making this process obsolete, because when people see this, what they think is that it's a joke."
Still, some delegates are cautiously optimistic. The UAE plans to increase oil production but has also invested heavily in clean technology.
"They're in a unique position to also push the positives," said Naseem, the negotiator from the Maldives. "I really hope the UAE can play a critical role in pushing for the kinds of transition — and renewable energies and technologies — that can help countries like us to exist longer."
Edited by: Jennifer Collins