What would Earth's temperature be without any greenhouse effect?

About 255 K (-18°C). The natural greenhouse effect adds ~33°C to reach the actual ~288 K (15°C).

If CO₂ doubles from 280 to 560 ppm, approximately how much warming occurs?

Climate sensitivity is approximately 3°C per doubling of CO₂ (range: 2.5-4°C).

Why is methane a stronger greenhouse gas per molecule than CO₂, yet CO₂ gets more attention?

CH₄ is ~80× more potent per molecule (20-year GWP), but CO₂ concentration is ~220× higher and persists for centuries vs. ~12 years for CH₄.

Pro 🔒~20 min

Greenhouse Effect

Solar radiation, infrared absorption, and global temperature

How it works

Greenhouse Effect demonstrates a key principle: The Sun emits primarily visible light, which passes through Earth's atmosphere and warms the surface. The Sun emits primarily visible light, which passes through Earth's atmosphere and warms the surface. The warm surface radiates infrared (IR) radiation back toward space. Greenhouse gases (CO₂, CH₄, H₂O, N₂O) absorb and re-emit IR in all directions, trapping energy in the lower atmosphere. This natural greenhouse effect raises Earth's average temperature from ~255 K to ~288 K (about +33°C). Increasing CO₂ from pre-industrial 280 ppm to today's 420+ ppm has enhanced this effect, causing ~1.1°C of warming. The relationship is roughly logarithmic: each doubling of CO₂ adds about 3°C (climate sensitivity). Methane is ~80× more potent per molecule but exists in much smaller quantities.

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Step-by-step

Adjust CO₂ and CH₄ sliders to see how greenhouse gas concentrations affect global temperature.
Yellow photons represent incoming solar radiation; red photons represent outgoing infrared.
Watch how more greenhouse gas causes more IR photons to be reflected back to the surface.
The thermometer shows the resulting surface temperature.

Key formulas

$T_s = T_{\text{eff}} \cdot (1 + \tau)^{1/4}$ Surface temperature depends on effective temperature and atmospheric opacity τ (greenhouse parameter)
$T_{\text{eff}} = \left(\frac{S(1-\alpha)}{4\sigma}\right)^{1/4} \approx 255\,\text{K}$ Earth's effective temperature without greenhouse effect: S = solar constant, α = albedo, σ = Stefan-Boltzmann constant

Frequently asked questions

What would Earth's temperature be without any greenhouse effect?: About 255 K (-18°C). The natural greenhouse effect adds ~33°C to reach the actual ~288 K (15°C).
If CO₂ doubles from 280 to 560 ppm, approximately how much warming occurs?: Climate sensitivity is approximately 3°C per doubling of CO₂ (range: 2.5-4°C).
Why is methane a stronger greenhouse gas per molecule than CO₂, yet CO₂ gets more attention?: CH₄ is ~80× more potent per molecule (20-year GWP), but CO₂ concentration is ~220× higher and persists for centuries vs. ~12 years for CH₄.