WHEN world leaders gather in Paris later this month to forge an agreement on climate change, they will discuss ways to use less fossil fuel, expand energy-efficient technologies and reduce carbon dioxide emissions. Yet even as our leaders are pushing us to use fewer resources, their vision will force us to use more.

Though energy from the sun and wind appears boundless, the resources needed to turn it into power are not. And as we move away from oil, gas and coal, there is increasing demand for the rare metals that are at the heart of green technology. In the process, we are trading one resource dependency for another, and unleashing a new set of economic and environmental ramifications.

These rare metals — a group of roughly 50 that includes indium, rare earths and gallium — are produced in small quantities, often several thousands of tons annually or less; blended with other metals; and traded in back-room deals. But don’t let their obscurity fool you. They are critical to green technology. Their unique properties make the products we buy smaller, faster and more powerful.

They are embedded in the tallest wind turbines, the smallest computer chip and in every battery. If we succeed in meeting the International Energy Agency’s minimum recommendation of nearly quadrupling wind power capacity by 2030, growing electric vehicle use more than 100-fold by 2025, and increasing battery efficiency, specialty metals like dysprosium and cobalt will take center stage.