Telegraph (India): The Maidan, the lush expanse of green spread across 5sq km in the heart of the city, acts as the lungs of Calcutta. It is the biggest carbon sink in the metropolis, recently crowned the carbon capital of India. A carbon sink is a natural or manmade reservoir that stores carbon- containing chemical compounds for an indefinite period. Other than oceans, plants act as natural carbon sinks, absorbing huge amounts of carbon dioxide, a greenhouse gas, through photosynthesis. A recent …