Climate Change Modeling

What is Climate Change Modeling?

Climate change modeling uses historical data and physics to project how Earth's average temperature responds to changes in greenhouse gases. Ice cores drilled in Antarctica preserve trapped air bubbles reaching back 800,000 years, recording both CO₂ concentration and temperature proxy data — and the two curves track each other almost perfectly through about eight major glacial-interglacial cycles. Since pre-industrial times (~1750), CO₂ has risen from 280 ppm to over 420 ppm, a level not seen in at least 800,000 years of natural cycles. The simulation lets you explore that full record, switch between four SSP emission scenarios with different assumed societal choices, and watch how the projected temperature curve for 2100 changes depending on which path humanity takes.

Parameters explained

CO₂ Concentration(ppm)

Sets the atmospheric CO₂ concentration in ppm (280–1200 ppm). Pre-industrial baseline is 280 ppm; today's level is ~420 ppm. Each doubling from the baseline adds approximately 3.7 W/m² of radiative forcing and ~3°C of equilibrium warming. Push toward 1200 ppm to explore worst-case RCP 8.5 end-of-century projections.

Climate Sensitivity(°C/2×CO₂)

Climate Equilibrium Sensitivity: the warming expected per doubling of CO₂, in °C (range 1.5–6 °C, IPCC likely range 2.5–4°C, best estimate 3°C). Lower values follow the optimistic end of model spread; higher values represent strong feedback amplification including water-vapor, ice-albedo, and cloud feedbacks.

Aerosol Forcing(W/m²)

Net aerosol radiative forcing in W/m² (range −2 to 0). Aerosols from industrial pollution and volcanic eruptions reflect sunlight, partially offsetting greenhouse warming. The current best estimate is about −0.5 W/m². Setting this to 0 removes the cooling mask and shows how much warming aerosols have suppressed.

Common misconceptions

• MisconceptionIf it snows heavily this winter, that proves global warming is fake.

  CorrectWeather is what happens on a given day; climate is the multi-decade average. A single cold event is well within normal weather variability even as the overall trend warms. Scientists measure climate change over 30-year baselines, not individual storms.

• MisconceptionCO₂ is a trace gas — only 0.04% of the atmosphere — so it can't possibly matter.

  CorrectConcentration doesn't determine impact alone; absorption spectrum does. CO₂ absorbs infrared radiation at specific wavelengths that other major gases (N₂, O₂) ignore entirely. Even a small amount blocks significant outgoing heat, much like a small amount of pigment can block most light in a solution.

• MisconceptionClimate has always changed naturally, so current warming is just a natural cycle.

  CorrectNatural cycles — Milankovitch, solar variation — do cause climate change, but they operate on timescales of tens of thousands of years and are well-tracked in ice-core data. Current warming of ~1.1°C in 150 years is several to tens of times faster than typical post-glacial natural warming rates (depending on the baseline used), and CO₂ is already 50% above any natural peak in 800,000 years.

• MisconceptionMore CO₂ means proportionally more warming — doubling CO₂ doubles the temperature rise.

  CorrectThe relationship is logarithmic, not linear. Each successive doubling of CO₂ adds roughly the same amount of forcing (~3.7 W/m²). This means going from 280 to 560 ppm has the same effect as going from 560 to 1120 ppm — diminishing returns at high concentrations.

• MisconceptionOcean warming is just a side effect of air temperature rising.

  CorrectThe ocean absorbs over 90% of the excess heat in the climate system and acts as a thermal buffer, delaying surface warming. Because of this ocean thermal mass, if CO₂ concentrations were held fixed, some additional committed warming would occur over decades. Under near-zero emissions scenarios where concentrations can gradually decline, global temperature is expected to roughly stabilize — though uncertainty remains across model projections.

How teachers use this lab

1. Deep-time vs. modern comparison: set timeRange to 800,000 with showCO2 on. Students identify the natural CO₂ ceiling (~280 ppm) across multiple glacial cycles, then advance timeRange to 200 to see the industrial spike above that ceiling. Ask: how long did it take naturally to change CO₂ by 100 ppm vs. industrially?
2. Scenario comparison activity: pairs run the simulation at scenario 1 and scenario 4, recording projected 2100 temperature for each. They calculate the difference (~2.6°C) and research one real-world impact that changes at that threshold (e.g., coral reef survival, sea level rise, crop yield).
3. CO₂-temperature lag analysis: set timeRange to 800,000 and showCO2 on. Ask students whether CO₂ always leads temperature changes or sometimes lags. This probes the difference between forcing (orbital → temperature → ocean CO₂ release) and feedback (industrial CO₂ → direct forcing).
4. Radiative forcing calculation: using the formula ΔF = 5.35 × ln(C/C₀) with C₀ = 280 ppm, students compute the forcing for today's 420 ppm (≈ 2.1 W/m²) and compare to a 560 ppm scenario. No calculus needed — just a calculator and the numbers from the sim.
5. Misconception probe — 'it was cold last week': before opening the simulation, poll the class on whether a local cold week disproves global warming. After exploring the 800,000-year record with clear multi-decade trends, revisit the question and have students articulate the climate vs. weather distinction in their own words, citing HS-ESS3-5.