Correct Option
The correct option is 2 and 3 only.
Explanation
Carbon dioxide (CO2) is a meteorologically significant variable gas in the atmosphere. It plays a crucial role in the Earth's heat budget by being transparent to incoming solar radiation but opaque to outgoing terrestrial radiation, thereby contributing to the greenhouse effect.
Statement-wise Analysis
- Statement 1 is Incorrect. Forests and oceans act as major sinks (reservoirs that absorb more than they release) of carbon dioxide, not sources. Forests absorb CO2 through photosynthesis, and oceans absorb it through dissolution and biological processes (phytoplankton). Sources primarily include volcanic activity, respiration, decay of organic matter, and anthropogenic activities like fossil fuel burning.
- Statement 2 is Correct. In the context of atmospheric chemistry and physical geography, the time taken for atmospheric CO2 to adjust to changes in sources and sinks (often referred to as the adjustment time or residence time in specific models) is estimated to be approximately 20 to 50 years.
- Statement 3 is Correct. The concentration of carbon dioxide in the atmosphere has been increasing steadily due to anthropogenic factors. The rate of increase is estimated to be about 0.5 % annually.
Key Takeaway
Carbon Dioxide (CO2) is a primary greenhouse gas for which forests and oceans serve as natural sinks. Its atmospheric concentration is rising annually due to the burning of fossil fuels and land-use changes.