If the Earth emits more of this invisible light than it absorbs from the Sun, the Earth cools off. As it cools off, the Earth emits less energy. This change also brings the Radiation Budget back into balance. This picture shows how the balance works. Absorbed sunlight pushes the Earth's temperature up.
Emitted heat pushes the temperature down.
When the two pushes balance each other, the Earth's temperature doesn't change - the radiation budget is in balance.