LE BOURGET, France—If you want to sound smart at the climate talks, stand in line at one of the Alto café espresso carts in the convention hall and say, in a knowing voice, “You know, it’s all about the money.”

That’s a cheap trick of course. Most things are about money, except money, which is about power. That was bound to be true at a global summit where government officials from 196 countries have gotten together to confront a global threat poised to upend the world system as we know it, and hash through solutions that could do the same—or be finessed carefully to keep things like they are.

The people with money and power go by a variety of names. Often they’re “developed countries,” as opposed to the “developing countries,” which, when spoken in a strong accent after an 18-hour day and maybe one too many trips to an Alto café, gets confusing. In the opaque bureaucratese that is the true UN language, they are “Annex II Parties” and “Non-Annex I Parties” (don’t ask). The idea is that some have profited hugely off the things that cause global warming, while others are poor and emit little carbon but—in one of those little ironies of the world—will suffer first and massively from climate change.

But all countries have rich and poor people. No one embodies this more than China, India, and Brazil—each home to hundreds of millions of impoverished people and some of the richest carbon emissions profiteers in the world. At the last major climate conference, Copenhagen in 2009, those three banded together with South Africa to form the “BASIC” bloc, in large part to negotiate against the United States. It got so bad that President Barack Obama and his top adjutants crashed their secret meeting in hopes of nailing down a deal. (When Hillary Clinton said, “Literally, President Obama and I were hunting for the Chinese,” that’s what she was talking about.) The talks ended in futility shortly thereafter.

On Tuesday, Day 9 at Le Bourget, the BASICs stood up again. In a joint statement to journalists, they called for flexibility and a “comprehensive, balanced, ambitious and legally binding agreement.” Then they got down to business. The ministers noted that developed countries promised in 2009 to “mobilize” $100 billion a year in “climate finance” for developing countries—and haven’t yet.

Granted, the original language was vague. In international aid-speak, you “pledge,” then sign “commitments” about how it’ll get spent, then finally “disburse” the money (usually Congress approves it—which ha, ha good luck). “Mobilize” suggests something outside that process; money moving on its own—perhaps from corporations, or existing projects—to somewhere else. What exactly counts as “climate finance” depends on who you ask on what day of the week.

To clarify things, the Organization for Economic Co-Operation and Development, which is basically a Paris-based consortium of rich countries, sat down and crunched the numbers to see how close we have gotten to $100 billion a year. Their answer: In 2013, developed countries mobilized $52 billion for climate finance. In 2014, it was $61.8 billion. Getting close!

The BASIC ministers cried foul. “Double accounting is not the real number,” India’s environment minister Prakash Javadekar said, shocking a number of reporters in the room who all started shouting “What?!” Then he repeated it.

“Developing countries say we are not seeing the money,” Chinese special envoy Xie Zhenhua added.

“It is very difficult to say what has been counted because the methodology has not been discussed as a collective,” chimed South Africa’s Edna Bomo Molewa.

Brazilian environment minister Izabella Teixeria got the testiest. “What is the real number? I’m not talking about projects. I’m talking about disbursements. OK?” she asked. “You need to show the numbers, you need to show the source, you need to show also the outcomes.”

No one on the dais would say exactly what they thought the real number was. So I chased down Javadekar, who walked me back to his temporary office (two can play at that game, Mrs. Clinton). He handed me a discussion paper from the Indian finance ministry. Its major objections: the OECD counted commitments, not disbursements; it didn’t clarify what was really new money, instead of money recycled from other projects; it counted loans; and it was letting rich countries “game the system” by identifying their own climate projects without third-party verification.

Taking those things into account, the Indian economists said the OECD’s 2014 estimate would drop by half, if not more. If you spread out the money promised over the five to seven years it usually takes to actually implement a project, the paper said, the real number could fall as low as $1 billion.

The OECD rejected that analysis. Yes, its count was “largely based on commitments” instead of disbursements, Simon Buckle, the OECD’s head of climate change told me in an email. (It’s a common practice in government-level aid analysis.) Yes, they included loans. And yes, developed countries self-reported their data, including what was “new and additional.” But that’s how everything works around here these days. “Self-reporting is the basis of reporting to the [UN Framework Convention on Climate Change]—on emissions as well as finance.”

“We have not taken any of this data at face value, and have rigorously adjusted it to eliminate double counting,” Buckle concluded. He said the OECD stands by the report.

This stuff is hard to track. The U.S. says it “allocated $15.6 billion in climate finance” since 2010, according to a report passed on by the State Department. That does not include the $3 billion it pledged—but has not delivered—to the Green Climate Fund. But I know from experience that tracking money gets confusing, even when you’re looking at a single event, like, say, the response to the 2010 earthquake in Haiti. The projects the U.S. included in its figure range from an action plan written for towns near glacial lakes in the Andes to mangrove restoration in the Solomon Islands to a mobile phone warning system for floods in Mozambique. Tracing what every project does, where the money really goes and so on is essential. No one has time to do that here.

Disagreement over the numbers is not necessarily going to derail the talks. Javadekar’s most dire prediction at the press conference was that major parties might need an extra day to negotiate. The BASICs are asking for stricter, more consistent, and more transparent accounting rules—ideas which, in principle at least, the U.S. seems to be on board with. The Obama administration has clearly made getting an agreement, and washing away the stain of Copenhagen, the priority.

And it will be an agreement Americans and their allies can continue making money off of. Secretary of State John Kerry, who’s been at the conference since Monday, told a room full of business representatives today, “The signal will be sent: The world is open for the creation of this new economy. … This is one of the greatest economic opportunities the world has ever seen.”

Deep down, the BASICs surely understand where the Americans are coming from. After all, they are often donor countries themselves. The Paris agreement is likely to include a line acknowledging that countries such as China, India, and Brazil will also be able to act as climate-finance donors if, as the emerging phrasing goes, they are “in a position to do so.” On Tuesday, those ministers boasted of their climate finance projects in poorer countries, all done individually and self-reported, according to their own criteria.

But wait, I asked. Isn’t that exactly the opposite of transparency and uniform accounting? Shouldn’t they have to do what they’re asking the developing countries to do, themselves?

That’s not part of the agreement, Javadekar replied.