Delhi Must Scale Up Biodiversity Parks To Mitigate Greenhouse Gases, Summer Heat

At a presentation in March at the India International Centre—on the ecological services rendered by biodiversity parks in Delhi—a suggestion was made by an audience member that these parks should be massively scaled up along the entire city stretch of the River Yamuna, so that they can act as heat sponges, particulate matter filters, carbon sinks and water storage and purification systems. 

The suggestion came from Deepak Pental, former vice chancellor of Delhi University and the agricultural scientist who led the DU team that developed genetically-modified mustard, which the government approved for cultivation last year. It was made to ecologist CR Babu, professor emeritus of DU’s Centre for Environmental Management of Degraded Ecosystems, which in collaboration with the Delhi Development Authority has set up seven biodiversity parks in Delhi.

The trigger for the suggestion was the estimate by a DU Professor of Finance and Business Economics that the Aravali Biodiversity Park in Delhi has stored about 9,000 tonne of carbon-dioxide equivalent (CO2e) in the trunks of adult trees and that another 1,200 tonne of CO2 equivalent are being sequestered every year.

Yamini Gupt, who did the study, said the findings are preliminary and not comprehensive as only 829 trees—aged 15-18 years—were included in the sample taken from 83 random plots of 100 sq. m. each, totalling two acres.

If the age and distribution of the trees in the sample is the same across the 500-acre forested area of the 692-acre park, there would be about two lakh adult trees, she said.

Gupt had arrived at the estimate by projecting the sample findings onto the rest of the forested area. The actual carbon capture would be higher if grasses and plants, shrubs and young trees are included. She has also not estimated the carbon stored in soil. In addition, she estimates that the park prevents the runoff of 1,10,000 cubic feet of rainwater (about three million litres) a year. The avoided pollution of greenhouses gases is about 14.6 tonne a year. 

The carbon captured by the park may seem a drop in Delhi’s ocean of pollution. In 2014, two professors of IIT Kanpur had estimated the city’s annual dump of polluting gases at nearly 38 million tonne of carbon dioxide equivalent. The study was done for the Delhi Administration’s Department of Environment.

Nine years later, the load would be higher despite more efficient vehicles replacing less efficient ones, the prohibition of quite a few polluting activities, and a host of measures taken to scrub the air. But the city’s population has increased, and the study estimated that Delhi’s per capita emission was 2.26 tonne of CO2 equivalent, which was less than that of Beijing, London and Tokyo but about 1.5 times the national average. 

According to Babu, biodiversity parks can be developed on 7,000 hectares of the Yamuna floodplains, along the 22 km most polluted stretch of the river from Wazirabad in the north to Jaitpur in the south, after about 2,000 hectares are taken away for projects like riverfront development.

A simple calculation, based on Gupt’s estimate, shows that about three lakh tonne of CO2 equivalent can be captured if these 7,000 acres are restored to the vegetation that existed before urbanisation destroyed it. (Of course, the vegetation of the hilly Aravali ranges is quite different from that of the floodplains, and carbon capture by mature trees is higher than that of young ones).

The parks provide other ecological services as well. They lower the local temperature and can cause rainfall in pockets. According to the Indian Meteorological Department, temperatures last summer were consistently 3 degrees Celsius to 8 degrees Celsius above normal, breaking many decadal and some all-time records in several parts of the country, including Delhi.

This year is likely to be hotter, especially because of the likelihood of El Nino, a southern Pacific warm water phenomenon associated with droughts or deficient rainfall in South Asia. With climate change, summers will be hotter than usual and there will be lethal hot spots. 

Though the term 'biodiversity parks' conjure images of prettified forests for picnics and birdwatching, they are not artificial implants. They are restoration of the vegetation that existed.

As Babu explains, they are unique landscapes of wilderness where ecological assemblages of native species are recreated in the form of biological communities over a few hundred acres of degraded or marginal land.

At the Yamuna biodiversity park, the soil was alkaline. There were bushes, brambles, grasses and trees that thrived in sodic soils (high proportion of sodium ion). The restoration was done by desilting the wetlands. No structures were built. River basin plant and tree communities were brought back over a period of 10 years. These attracted migratory birds and animals native to the grasslands and forests, which Babu calls a ‘tropic cascade’, as they are tiered jungles.  Now, there are nearly 1,000 species of plants in about 35 forest communities that live off each other. 

It turns out that Pental’s suggestion is not novel. In an order of July 2018 on the Yamuna Action Plan, the National Green Tribunal suggested that biodiversity parks like the ones by CEMDE should be established on the Yamuna flood plains from Wazirabad to Okhla. For this purpose, it said, the DDA, should make the land (as it’s the owner) available to the forest department. In another order of August 2018, the NGT said that the Ganga Action Plan should include biodiversity parks.

There is a three-member committee headed by Babu for biodiversity parks along the Yamuna. Faiyaz Khudsar, the scientist-in-charge of the Yamuna Biodiversity Park said he is preparing a plan for five more biodiversity parks along the Yamuna. According to him, there can be a network of many more.

A group of concerned citizens has planned a human chain in the first week of June to create awareness about the importance of biodiversity parks and urge the government to be ambitious.

Ravi Sharma, president of the IIT Alumni Council, which, according to him, brings finance and technology together for projects that benefit the nation, wants NGOs to step forward to develop the biodiversity parks. 

Scaling up the parks so that they make a palpable difference to Delhi’s environment should become a citywide mass movement. This will encourage similar action in other polluted cities along the Yamuna and the Ganga. Pollution and climate change are too important to be left for governments alone to tackle.