Negotiators from around the world are in Azerbaijan this week for the annual United Nations climate conference. COP29.

This year’s central question: How much should richer countries pay to help developing countries transition to cleaner energy and adapt to the effects of climate change?

Industrialized countries are already funding these efforts after the COP agreement in 2009. Now, negotiators need to decide which other countries might be in that group and how much more those nations will commit in the coming years.

Yale University professor Kenneth Gillingham said some countries have historically been more responsible for heat-trapping carbon in the atmosphere than others, and that’s the origin of these negotiations.

“It is really the richer countries of the world that are predominantly leading the climate change problem that we have today,” he said.

Much of the blame falls on the United States, the United Kingdom and most of Europe. These countries want poorer countries to reduce their carbon emissions as well and have said they will help finance this task.

“Industrialized countries have agreed in principle to provide this type of financial assistance many times in the history of climate negotiations,” said Kelly Sims Gallagher, dean of the Fletcher School at Tufts University.

This is where things get complicated: The list of industrialized countries that had to pay was created in the 1990s.

“So countries like China were taken into account, and in the 1990s, most of them were developing countries in terms of per capita income. “But conditions have changed a lot,” he said.

China, in particular, is now much richer and more industrialized. However, it is not officially on hold in terms of climate finance. This has been a big point of contention at the COP this year, said Rishikesh Ram Bhandary, deputy director of Boston University’s Global Economic Governance Initiative.

“How do you bring politics and reality together in one place so that we can come to an agreement that actually works for everyone?” he said.

Negotiators also need to agree on a figure when determining who pays, said Ian Mitchell, senior policy researcher at the Center for Global Development. “Most people agree that the needs are in the trillions of dollars a year,” he said.

Mitchell has just landed in Azerbaijan for COP29. He said he was not optimistic that countries coming together would agree on an amount to meet those needs.