It was a long time ago when Kolkata had a number of roads covered with canopies of trees. Over the years, the green covers changed.
One of the most beautiful tree-lined roads was VIP Road. It had large trees on both sides. Most of them were Krishnachura, Radhachura, Palash, and Gulmohar and were in full colours in season.
In the springtime, the Krishnachura and Palash trees were a riot of red while Radhachuras were bright yellow.
Not only did they create a visual feast but offered shades to the pedestrians.
In fact, green covers help reduce the surface temperature of roads.
What is Green Cover?
Green cover, which includes trees, plants, and vegetation, plays a vital role in containing summer heat in a variety of ways.
In Kolkata, we have many old trees in different areas. Still today, some roads have enough green cover above them.
Apart from the trees, Kolkata also has its Maidan and areas like Rabindra Sarovar, Alipore Zoo, and Victoria Memorial grounds that have a high concentration of vegetation.
Maidan itself accounts for 2.5% of the total open space in Kolkata.
Why is Urban Green Cover Important?
Today we fighting a fierce battle against deforestation. The reduction of urban green cover is directly responsible for a rise in temperature in cities.
Therefore, a vigorous forestation programme is essential for maintaining summertime temperatures in cities like Kolkata.
The following are some ways in which green cover helps:
Absorption of heat: Trees and plants absorb heat through a process called transpiration. This means that they absorb heat and release water vapour into the atmosphere, which cools the air around them.
Shade: Trees provide shade, which helps to reduce the amount of direct sunlight that reaches the ground, and hence, reduces the temperature in that area.
Evaporation: Plants and trees also release moisture into the air through a process called evapotranspiration. This helps to cool the surrounding air, especially during hot summer months.
Reduction of carbon dioxide: Trees and plants absorb carbon dioxide from the atmosphere and release oxygen through the process of photosynthesis. This helps to reduce the amount of greenhouse gases in the atmosphere, which contributes to global warming.
A Paucity of Open Spaces in Kolkata
However, fast-paced urbanisation in Kolkata and adjoining areas has created an environmental emergency.
The city’s open space is shrinking to an alarmingly low level in the last decade. According to the World Health Organisation (WHO), a city must have a minimum of 15% open space.
A study conducted by Society for Environment and Development revealed that Kolkata had slightly over 13% open space even in 2000.
A study about a decade later stated that the open space in the city reduced rapidly and now only 5.5%.
At a meagre 0.67 sq. m. open space per person in Kolkata, it is one of the cities with little green cover. WHO recommends at least 9 sq. m. per city dweller.
Other Indian cities are far ahead of Kolkata. In comparison, Mumbai and New Delhi at 18% and 19.09% have much higher open spaces. The national average stands at 19.49%.
Environmentalists are worried that there is no coordinated effort to turn the situation around in Kolkata.
Loss of Biodiversity in the City
The speedy loss of greenery in Kolkata is also diminishing its biodiversity. Apart from the reduction in the number of birds because of the dwindling number of trees to nest in, other forms of life such as squirrels, bats, and palm civets are finding it difficult to survive.
Rise in Pollution Levels in Kolkata
One of the major outcomes of decreasing green cover in Kolkata is the rise in air pollution. Because of the lack of open space, airflow is severely restricted, and airborne pollutants are trapped.
Dispersal of polluted air is hardly possible in such a scenario.
This is a reason why Kolkata has high pollution levels compared to other Indian cities, although the vehicular population in Kolkata is not very high.
The wetlands of East Kolkata had long acted as a basin to absorb pollution in Kolkata. Now that the areas surrounding the wetlands are dotted with different infrastructure development, the free flow of air is further restricted and polluted air has no area to escape.
Summertime Heat in Kolkata
As we can see from the discussion above, green covers are extremely important for sustainable cities. Without adequate greenery, the livability quotient takes a nosedive.
Adequate greenery is essential so the citizens can have superior mental health. Nature is a great healer of mental health problems due to the stress of modern living.
There is no better feeling than hearing the birds chirping, and watching colourful flowers and rain-washed green leaves. In Kolkata, the temperature during summer can be quite high, and the city experiences heat waves. A green cover helps to mitigate this by providing a cooling effect, which helps to make the city more livable during the summer months. Therefore, it is important to protect and increase green cover in Kolkata to contain summer heat.