Just as a simple lever can move heavy objects, rich nations are hoping another kind of leverage — the financial sort — can help them come up with the money that poorer nations need to cope with climate change. It involves a complex package of grants, loans and private investment, and it's becoming the major currency at annual United Nations climate talks known as COP29. Money is the key issue in Baku, where negotiators are working on a new amount for aid to help developing nations transition to clean energy, adapt to climate change and deal with weather disasters.