The table below lists information about several greenhouse gases: their typical atmospheric lifetime and their 20-year Global Warming Potential (GWP), which compares their warming effect to that of carbon dioxide over a shorter timescale.
| Greenhouse gas | Typical atmospheric lifetime (years) | Global Warming Potential (20-year GWP) |
|---|---|---|
| Carbon dioxide (CO2\text{CO}_2CO2) | 50 – 200 | 1 |
| Methane (CH4\text{CH}_4CH4) | 12 | 84 |
| HFC-134a (CH2FCF3\text{CH}_2\text{FCF}_3CH2FCF3) | 14 | 3710 |
| Sulfur hexafluoride (SF6\text{SF}_6SF6) | 3200 | 17500 |
Which gas in the table has the greatest warming effect per unit mass over 20 years?
Name a greenhouse gas that is not listed in the table.
The greenhouse impact of any gas is determined by factors including:
Methane (CH4\text{CH}_4CH4) has a significantly higher GWP than carbon dioxide (CO2\text{CO}_2CO2). Suggest why carbon dioxide still contributes much more to overall global warming.
Suggest why it has been possible to successfully regulate and reduce industrial emissions of synthetic gases like HFC-134a, while reducing carbon dioxide emissions remains extremely challenging.
State two methods humans can implement to reduce emissions of methane (CH4\text{CH}_4CH4) into the atmosphere.
Describe two specific ways that global warming can impact marine habitats.
