Greenhouse Effect Strength Calculator
Compute greenhouse effect strength using validated scientific equations. See step-by-step derivations, unit analysis, and reference values.
Formula
GHE = Ts - Te; dF = 5.35*ln(CO2/CO2base); dT = ECS*dF/F2x
Where GHE is greenhouse warming, dF is radiative forcing, ECS is equilibrium climate sensitivity, F2x is forcing for CO2 doubling.
Worked Examples
Example 1: Present Earth Greenhouse Effect
Problem: Calculate greenhouse effect for Earth with surface temp 288 K, effective temp 255 K. CO2 at 420 ppm vs 280 ppm.
Solution: Greenhouse warming = 288 - 255 = 33 K\nSurface emission = 5.67e-8 * 288^4 = 390.1 W/m2\nTOA emission = 5.67e-8 * 255^4 = 239.7 W/m2\nCO2 forcing = 5.35 * ln(420/280) = 2.17 W/m2
Result: GHE: 33 K | Trapped: 150.4 W/m2 | CO2 forcing: 2.17 W/m2
Example 2: Doubled CO2 Scenario
Problem: Radiative forcing and warming if CO2 doubles from 280 to 560 ppm with ECS of 3.0 K.
Solution: CO2 forcing = 5.35 * ln(2) = 3.71 W/m2\nExpected warming = 3.0 K\nFeedback param = 3.71 / 3.0 = 1.24 W/m2/K
Result: Forcing: 3.71 W/m2 | Warming: 3.0 K | Feedback: 1.24 W/m2/K
Frequently Asked Questions
How is greenhouse effect strength measured?
Greenhouse effect strength can be quantified in several complementary ways. The simplest measure is the temperature difference between the actual surface temperature and the effective radiating temperature which for Earth is approximately 33 K. The energy-based measure calculates the difference between surface emission and top-of-atmosphere outgoing longwave radiation yielding about 150 watts per square meter for Earth. The normalized greenhouse effect is a dimensionless ratio that equals 1 minus the fourth power of the ratio of effective to surface temperature.
How does water vapor amplify the greenhouse effect?
Water vapor is the most abundant greenhouse gas and responsible for about 50 to 70 percent of the total atmospheric greenhouse absorption. It acts as a powerful positive feedback amplifier because warmer air holds more water vapor following the Clausius-Clapeyron relation which predicts roughly 7 percent more vapor per degree Celsius of warming. As CO2 warms the atmosphere increased water vapor further enhances infrared absorption approximately doubling the warming that CO2 alone would produce. However water vapor cannot independently drive long-term warming because it has a short atmospheric residence time of about 10 days.
How does the greenhouse effect differ on Venus Earth and Mars?
The three terrestrial planets demonstrate vastly different greenhouse effect strengths. Venus has an extreme greenhouse effect of about 505 K raising surface temperature from 232 K to 737 K driven by a dense 90-bar CO2 atmosphere. Earth has a moderate greenhouse effect of about 33 K with its 1-bar atmosphere containing trace CO2 and abundant water vapor. Mars has a negligible greenhouse effect of only about 5 K despite its 95 percent CO2 atmosphere because atmospheric pressure is only 0.006 bar too thin to trap significant infrared radiation.
How do scientists project future greenhouse warming?
Future greenhouse warming projections use comprehensive Earth system models that simulate coupled interactions between atmosphere ocean land surface ice and biogeochemical cycles. These models are driven by scenarios of future greenhouse gas emissions called Shared Socioeconomic Pathways spanning a range from aggressive decarbonization to continued high emissions. The models solve fundamental equations of fluid dynamics thermodynamics and radiative transfer on three-dimensional grids. Results from dozens of independent models are combined to assess the range of possible outcomes.
How do greenhouse gases trap heat?
Greenhouse gases (CO2, methane, N2O, fluorinated gases) absorb and re-emit infrared radiation, warming the atmosphere. Global Warming Potential (GWP) compares gases to CO2 over 100 years: methane has a GWP of 28, N2O is 265. Total forcing is measured in watts per square meter and currently exceeds 3 W/m^2.
Is my data stored or sent to a server?
No. All calculations run entirely in your browser using JavaScript. No data you enter is ever transmitted to any server or stored anywhere. Your inputs remain completely private.