A few days ago, at an ornate hilltop hotel in Azerbaijan’s wine country with panoramic views of the Caucasus foothills, the world’s top climate diplomats debated how to marshal whopping amounts of money to fight global warming and compensate poor and vulnerable countries that suffer its worst effects.

“Some say single-digit trillions. Some say double-digit,” said Yalchin Rafiyev, Azerbaijan’s chief climate negotiator.

The meeting was a pre-meeting, of sorts, for the main event: November’s United Nations sponsored climate negotiations, known as COP29, to be held in the seaside capital, Baku, a few hours away.

At previous summits, the world’s nations had struggled to agree on a seemingly basic premise in the fight against climate change, namely that humanity’s reliance on fossil fuels must be curbed as quickly as possible.

At last year’s event, to great fanfare, the world agreed on that.

But it was just words on paper. This year, it comes down to cold, hard cash. How much will this all cost, and who foots the bill? COP29 is meant to answer that question.

It’s a daunting task for the host country, which must shepherd the contentious debate. Fearing that November’s two-week summit wouldn’t give delegates enough time to hammer out the details, the Azerbaijanis invited diplomats to the recent weekend retreat.