CO₂ and Radiative Forcing
Lesson notes
Overview
Forcing grows with the logarithm of CO₂ concentration. This topic is rated intermediate and is number 66 of 98 in Earth & Space. Builds on the basics with relationships, methods and trade-offs.
What you are seeing
The panel above shows a graph of the function. Each slider changes one parameter, so you can see exactly how the curve bends, shifts or stretches. The animation is drawn live from the model, so everything you see responds to the sliders. Press Space to pause, use Restart to replay from the start, and change the speed to slow down quick events.
In depth
The extra heat trapped by carbon dioxide is described by ΔF = 5.35 ln(C/C₀) W/m². Because the relationship is logarithmic, each doubling of the concentration adds the same forcing, about 3.7 W/m², and the effect of each additional molecule declines as the absorption bands saturate. Pre-industrial CO₂ was 280 ppm and it is now above 420 ppm, giving a forcing of about 2 W/m² from CO₂ alone.
Reading the relationship
The expression "ΔF = 5.35 ln(C/C₀)" is a compact summary of the idea. It uses the symbols Δ, F, C, C₀; name what each one stands for before you start. Notice that it contains a ratio, so increasing the denominator makes the result smaller, and a logarithm, which turns multiplication into addition and compresses large values. Then use the sliders to see how changing one quantity changes the others.
A guided exploration
1. Set every slider to its middle value and note the shape of the curve. 2. Move one slider at a time and describe whether the curve shifts, stretches or turns. 3. Find the value where the behaviour changes sharply, then connect it to the formula.
Try this
Predict the outcome first, then test extreme slider values to find where the pattern changes or breaks.
Common pitfalls
Earth and space systems work on very different scales of time and distance. Check which scale a number refers to before comparing it with another.
How it connects
It builds on “Sea Level Rise from Thermal Expansion”, the topic before it in Earth & Space. Once you are comfortable, continue with “Keeling Curve Trend”.
Why it matters
Earth and space science helps us understand our planet, its climate and the wider universe.
Where you might use it
- Revising “CO₂ and Radiative Forcing” before a class, exam or certification
- Forecasting weather and understanding climate records and their uncertainty
- Planning for earthquakes, floods and other natural hazards in cities
- Interpreting satellite images, space missions and the age of rocks and stars
Frequently asked questions
What is CO₂ and Radiative Forcing?
Forcing grows with the logarithm of CO₂ concentration. It is an intermediate topic in Earth & Space.
How do I use the CO₂ and Radiative Forcing simulation?
The panel at the top shows a graph of the function. Each slider changes one parameter, so you can see exactly how the curve bends, shifts or stretches. Move the sliders one at a time, then press Space to pause the animation and look closer.
What does the formula mean?
The expression ΔF = 5.35 ln(C/C₀) packs the idea into symbols. Name each symbol first, then change one quantity with the sliders and see which others respond.
Who is this topic for?
Builds on the basics with relationships, methods and trade-offs. If the quiz feels hard, reread the lesson notes and try the previous topic first.
What should I learn before this?
Start with “Sea Level Rise from Thermal Expansion”, the previous topic in Earth & Space. Each topic in a subject builds on the ones before it.
How do I track my progress?
Press “Mark as learned” on this page. Progress is stored only in this browser and is never sent anywhere. The Browse page can show topics you have learned or still need to learn.