Monitoring greenhouse gases (GHGs) is important to understand climate change and track emissions. Various methods are used depending on the gas type, location, and accuracy needed.
1. Ground-Based Monitoring
- Infrared Gas Analyzers (IRGA): Measure CO₂, CH₄, and N₂O in the air by detecting absorption of infrared light.
- Gas Chromatography (GC): Separates and measures different greenhouse gases from air samples.
- Flasks and Canisters: Collect air samples at specific locations for later lab analysis.
- Eddy Covariance Systems: Measure fluxes of CO₂ and CH₄ between ecosystems (like forests or fields) and the atmosphere.
2. Remote Sensing (Satellite Monitoring)
- Satellites equipped with sensors detect GHG concentrations globally.
- Examples:
- NASA’s OCO-2: Measures atmospheric CO₂.
- GOSAT (Japan): Monitors CO₂ and CH₄.
- Uses spectroscopy techniques to detect specific gases from space.
3. Atmospheric Monitoring Networks
- Global networks of stations continuously monitor GHGs.
- Example: NOAA Global Greenhouse Gas Reference Network tracks CO₂, CH₄, and N₂O at multiple sites worldwide.
4. Proxy and Indirect Methods
- Ice cores: Measure past GHG concentrations trapped in bubbles.
- Tree rings and sediments: Provide indirect evidence of historical GHG levels.
5. Sensor-Based Methods
- Portable electrochemical sensors or laser-based sensors can measure GHGs on-site.
- Useful for local emission monitoring in industrial areas or landfills.
In short:
Greenhouse gases are monitored using:
- Ground-based instruments (GC, IRGA, sensors)
- Satellites and remote sensing
- Global monitoring networks
- Proxy methods (ice cores, sediments)
These methods help track current emissions, study trends, and support climate policies.