Worked examples
The 1986 publication established foundational metrics for methane’s radiative forcing relative to carbon dioxide. The following examples illustrate the application of these findings to quantify global warming potential and atmospheric lifetime impacts.
Example 1: Calculating Global Warming Potential
A common metric is the 100-year Global Warming Potential (GWP100). The 1986 study determined that methane has a GWP100 of approximately 21 compared to CO2. To find the equivalent CO2 mass for a methane emission:
- Given: 1 tonne of CH4 emitted.
- Formula: CO2 equivalent = Mass_CH4 × GWP100.
- Calculation: 1 t × 21 = 21 tonnes CO2e.
This means 1 tonne of methane exerts the same radiative forcing as 21 tonnes of CO2 over a century.
Example 2: Atmospheric Lifetime Contribution
The 1986 analysis identified methane’s atmospheric lifetime as roughly 12 years. To estimate the cumulative presence of an annual emission:
- Given: Annual emission rate of 400 million tonnes CH4/year.
- Formula: Total atmospheric mass ≈ Annual rate × Lifetime.
- Calculation: 400 Mt/y × 12 y = 4,800 Mt CH4.
This steady-state mass drives the instantaneous radiative forcing.
Example 3: Radiative Forcing Impact
The study quantified methane’s contribution to total radiative forcing. If total forcing is 2.5 W/m² and methane accounts for ~20%:
- Given: Total forcing = 2.5 W/m².
- Methane share = 20%.
- Calculation: 2.5 W/m² × 0.20 = 0.5 W/m².
This 0.5 W/m² represents methane’s direct thermal impact on the climate system in the 1986 baseline.
See also
- Description of hydropower energy
- Parabolic trough collector system
- Frequency Control of Power System with Wind Power Integration
- Paris Agreement: Structure, Implementation, and Global Impact
- Landfill gas power