Earth's Radiative Energy Imbalance and Climate Sensitivity calculations
(change values in the yellow cells, then press the Tab key  ↹  to recalculate)
Data-entry cells are yellow my best estimates alternative scenarios
Calculated cells are blue alarmist skeptic
value units value value references & notes
Starting CO2 level ppmv Preindustrial / LIA (1751) level is usually estimated to have been 277 - 280 ppmv
Current CO2 level ppmv
Current CO2 forcing, as fraction of a doubling, Fcd log2( current_CO2_level / starting_CO2_level )
For all the rest of the input fields, higher values are "more alarmist," and lower values are "more skeptical."
ECS / TCR, ETratio Lewis & Curry, 2018
IPCC AR5 WG1 Table 9.5, p.818
Unealized portion of (ECS-TCR), Ufract
Fraction of (Fcd% of) ECS realized, Fr (1/ETratio) + ((1-Ufract)×((ETratio-1)/ETratio))
Fraction of (Fcd% of) ECS unrealized ("in the pipe") 1 - Fr
Actual realized warming to date since LIA (1780). Wtd °C Law dome ice cores show CO2 level was 280 ppmv in 1780
Anthropogenic fraction of warming to date, Fa
Assumed natural warming since LIA, Wn °C Wn = (1 - Fa) × Wtd
Fraction of anthropogenic warming that's from CO2, Fc
Realized warming since LIA due to CO2 alone, Wc °C Wc = Wtd × Fa × Fc
Expected equilibrium warming from CO2 alone, Ec °C Ec = Wc / Fr
Realized warming since LIA due to CO2 + other anthro, Wa °C Wa = Wtd - Wn ≡ Wc / Fc
Expected equilibrium warming due to CO2 + other anthro, Ea °C Ea = Wa / Fr (assuming same % unrealized for CO2 and other GHGs)
Expected equilibrium warming (natural+CO2+other GHGs), Ew °C Ew = Ea + Wn (assuming natural warming component will be unchanged)
Practical climate sensitivity (between ECS & TCR), S °C Wc / Fcd (corrected 9/9/2023)
TCR °C ECS / ETratio
Radiative forcing from a doubling of CO2, RFd W/m²
Equilibrium warming per W/m² forcing, Ef °C/(W/m²) ECS / RFd
Remaining unrealized warming "in the pipe", Wu °C Ew - Wtd
Radiative Imbalance calculated from unrealized warming W/m² Wu / Ef
Radiative imbalance (assumed), Ri W/m² NCA4 Global Mean Energy Budget of Earth
Cross-check radiative imbalance & unrealized warming estimates:
Unrealized warming calculated from assumed radiative imbalance, Ri °C Ri × Ef (compare this with Wu)
Note: "other anthro" means other anthropogenic forcings, including other GHGs, and aerosol / particulate pollution abatement
Contact: Dave Burton
This web page was created from a MS Excel spreadsheet using WebWorksheet:
The shreadsheet (source .xlsx file) can be downloaded here: