Write a short note on Long Half-life.
Long Half-life refers to the exceptionally long atmospheric residence time of carbon dioxide (CO2), meaning it persists in the atmosphere for hundreds to thousands of years after emission. Unlike short-lived pollutants, CO2 effects are cumulative and intergenerational.
| Timeframe | CO2 Removed | Process |
|---|---|---|
| ~30 years | ~40% | Ocean uptake, vegetation absorption |
| Few centuries | ~30% | Deep ocean mixing, soil absorption |
| Millennia (1000+ years) | ~20-30% | Rock weathering, ocean sediments |
| Gas | Atmospheric Lifetime | GWP (100-year) |
|---|---|---|
| CO2 | 300-1000+ years | 1 |
| Methane (CH4) | 12 years | 28-36 |
| Nitrous Oxide (N2O) | 121 years | 265-298 |
| SF6 | 3,200 years | 23,500 |
Key Point: Even if all emissions stopped today, atmospheric CO2 would remain elevated for centuries, and temperatures would not immediately return to pre-industrial levels. This "committed warming" makes early action crucial.
The long half-life of CO2 means emissions persist in the atmosphere for centuries to millennia, creating cumulative effects and intergenerational impacts. Unlike short-lived pollutants, CO2 builds up over time, making climate change a long-term problem requiring immediate action. This characteristic underscores the urgency of reducing emissions now - the longer we wait, the more CO2 will accumulate, and the more difficult and costly climate stabilization becomes.