Money: It’s the most contentious subject at the international climate talks this week in Baku, Azerbaijan. How much? From where? What for?

Getting big cash commitments would be hard enough without wars, a pandemic and inflation having drained the reserves of rich countries that are expected to help poorer ones cope with climate hazards.

It just got even harder. The election of Donald J. Trump as president of the United States all but guarantees that the world’s richest country will not chip in. (Mr. Trump has said he would withdraw from the global climate accord altogether, as he did during his first term.)

So now what?

Several creative ideas are circulating to raise money for countries to invest in renewable energy and adapt to the dangers of climate change. They include levying taxes, tackling debt and pushing international development banks to do more, faster.

The new proposals come with steep hurdles of their own, but the traditional way of raising money — passing around the hat and asking donor countries to make pledges — has failed to meet the need.

The last time a climate finance goal was established, in 2009, rich countries promised to mobilize $100 billion a year by 2020. They were two years late in meeting that target, and about 70 percent of the money came as loans, infuriating already heavily indebted countries.