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Greenhouse Effect & Climate Lab

Investigate Earth's energy budget, the greenhouse effect, and how CO₂ concentration drives radiative forcing and global temperature change. Explore feedback loops and compare emission scenarios from aggressive mitigation to business as usual.

Guided Experiment: CO₂ and Temperature Response

If you increase atmospheric CO₂ from pre-industrial levels (280 ppm) to double that value (560 ppm), how much warming do you predict?

Write your hypothesis in the Lab Report panel, then click Next.

Controls

CO₂ Concentration420 ppm
Albedo (reflectivity)0.30
Solar Constant1361 W/m²
Climate Sensitivity0.80 °C/(W/m²)
Include Feedbacks
Measurement Noise0.10 °C

Results

Teq=[S(1−α)4εσ]1/4=289.6  KT_{\mathrm{eq}} = \left[\frac{S(1-\alpha)}{4\varepsilon\sigma}\right]^{1/4} = 289.6 \;\text{K}
Bare-Earth Temp
254.6 K
Equilibrium Temp
289.6 K
Emissivity (ε)
0.597
Radiative Forcing
2.17 W/m²
Temp Anomaly (ΔT)
+1.74 °C
Greenhouse Warming
+35.0 K
Solar Absorbed
238.2 W/m²
Outgoing Longwave
238.2 W/m²

Radiative Forcing vs CO₂

Data Table

(0 rows)
#TrialCO₂(ppm)AlbedoSolar In(W/m²)LW Out(W/m²)T_eq(K)
0 / 500
0 / 500
0 / 500

Reference Guide

Energy Budget

Earth absorbs a fraction of incoming solar radiation and re-emits energy as infrared (longwave) radiation. At equilibrium, energy in equals energy out.

Teq=[S(1−α)4εσ]1/4T_{\mathrm{eq}} = \left[\frac{S(1-\alpha)}{4\varepsilon\sigma}\right]^{1/4}

S is the solar constant (1361 W/m²), α is albedo (reflectivity), ε is effective emissivity, and σ is the Stefan-Boltzmann constant.

Greenhouse Effect

Greenhouse gases (CO₂, H₂O, CH₄) absorb outgoing infrared radiation and re-emit it, trapping heat. Without this effect, Earth's average temperature would be about 255 K (-18 °C) instead of the current 288 K (15 °C).

The effective emissivity ε represents how efficiently Earth radiates to space. More greenhouse gases lower ε, raising the equilibrium temperature.

Radiative Forcing

Radiative forcing measures the change in energy balance due to a perturbation (such as increased CO₂). The IPCC simplified formula gives forcing as a logarithmic function of CO₂ concentration.

ΔF=5.35ln⁡ ⁣(CO2CO2,ref)  W/m2\Delta F = 5.35 \ln\!\left(\frac{\mathrm{CO_2}}{\mathrm{CO_{2,ref}}}\right) \;\text{W/m}^2

Doubling CO₂ from pre-industrial (280 ppm) to 560 ppm produces about 3.7 W/m² of forcing, leading to roughly 3 °C of warming.

Climate Sensitivity

Climate sensitivity describes how much temperature changes per unit of radiative forcing. The equilibrium climate sensitivity (ECS) for a CO₂ doubling is estimated at 2.5 to 4 °C (IPCC AR6).

ΔT=λ×ΔF\Delta T = \lambda \times \Delta F

Feedbacks (ice-albedo, water vapor, cloud) amplify or dampen the initial warming. Positive feedbacks like water vapor roughly double the direct CO₂ warming effect.