On the second day of the climate summit in Paris, negotiators sent heads of state home and got down to the real business. To many countries, it boils down to one question: who pays?

Today, the world’s poorest countries pushed the developed economies to fulfill a promise to provide $100 billion to developing countries. This case has been made consistently by one of the most important delegations in Paris: India.

Indian soon will be the biggest importer of coal, and the largest source of new demand for oil. Post-war America used to be that country. But India, population wise, is four Americas. And hundreds of millions of its people are just starting to move up the energy ladder.

“The state of Bihar is home to 100 million people,” said University of Chicago economist Michael Greenstone. “Per capita electricity consumption is about 200 kilowatt hours per person per year. In the U.S. it’s about 65 times higher.”

The problem is India is already the world’s third-biggest emitter of carbon dioxide. And as its people plug in, even an ambitious build-out of solar energy will still require additional power from coal, the cheapest source of electricity.

So India’s emissions, under its Paris climate pledge, could double. Many call this a growth-climate paradox…