The "energy balance" approach is not obvious to many people I spoke with, academic or not. It goes along the lines
- "Earth is radiating more energy to space than it receives from the sun."
- "Can't be! The sun is sooo hot".
- "But if it were not so, Earth would warm up by a massive amount - every hour, every day."
- "uhm, possibly."
- "and then there's energy from inside the Earth, vulcans, magma, decay heat of radioactive materials, and Earth's core slowly solidifying - all that energy plus that from the sun must be radiated away to keep today's temperatures."
- "hadn't thought of these, well..."
- "And that's why I want to put as little as possible of a thermal shield around earth."
- "Oh. Yes."