The fact you don’t even understand this basic fact and yet are so certain should concern you.
1. Logarithmic effect of CO₂
• The warming effect of carbon dioxide grows logarithmically with concentration, not linearly.
• This means the first 100 ppm of CO₂ caused a much larger temperature impact than, say, an increase from 400 → 500 ppm.
• Each additional molecule of CO₂ contributes less extra warming because much of the infrared spectrum it absorbs is already saturated.
2. Geometry of “forcing”
• Scientists describe this as radiative forcing, measured in watts per square meter.
• Roughly, each doubling of CO₂ concentration produces about +3.7 W/m² of forcing, which translates (with climate sensitivity) to ~1.5–4.5°C warming.
• So it takes geometrically more CO₂ to achieve each additional degree of warming. For example:
• Going from 280 → 400 ppm may give ~1°C warming.
• Going from 400 → 560 ppm (another 160 ppm) gives another ~1°C.
• Going from 560 → 840 ppm (280 ppm more) gives another ~1°C.
• And so on — the increments needed get larger each time.