So the problem isn't just the type of energy we're using, it's what we're doing with it. What would we do with 100 per cent clean energy? Exactly what we're doing with fossil fuels: raze more forests, build more meat farms, expand industrial agriculture, produce more cement and heap up more landfills with waste from the additional stuff we would produce and consume, all of which will pump deadly amounts of greenhouse gas into the air. We will do these things because our economic system demands endless economic growth. Switching to clean energy will do nothing to slow this down.