$1 trillion a year. That's what the investment in renewable energy and energy efficiency needs to reach by 2030 to keep global heating within the 1.5°C limit set by the Paris Agreement, alongside adapting our infrastructure to stronger storms, rising seas, and disrupted food and water supplies. On top of that, countries also need to invest in their own energy transition at home - so the full bill, external funding plus domestic investment combined, is even bigger. But that $1 trillion from wealthier nations is the critical piece, since it has to come from those most responsible for the crisis, not from the countries least responsible for it.
It's not just about the amount, though - it needs to be good quality funding: grants, not loans with high interest rates that trap struggling countries in debt; transparent, accountable agreements people can actually scrutinize; and local leadership, so funding decisions reflect what communities need, not what the financier wants.