Sooty Minarets: Effect of Climate Change on the Heritage Sites of Delhi

The effect of climate change on the heritage sites of Delhi is real. Can the damage be reversed?

India Gate, located in the middle of New Delhi, is a triumphal arch created in a fusion of architectural styles, most notably the Arc de Triomphe in Paris.

It was constructed as a military memorial to remember Indian troops who perished in World War I.

Photo: Soham Prasad

Every year, a fresh layer of sooty automobile pollution falls on India Gate's red sandstone slabs, obscuring the names of Indian martyrs from World War-I.

As the ozone layer thins, the protective filter of the atmosphere weakens, resulting in increased UV radiation.

This radiation eventually decomposes pigments in red sandstone, turning it yellow.

Humayun's Tomb, located in Delhi, is a fine example of Mughal architecture and is sometimes seen as a forerunner to the Taj Mahal.

The mausoleum was constructed in 1572 and is the final resting place of Mughal Emperor Humayun.

The secondary domes of the Humayun's Tomb have a thin layer of pollutants – a patina - on the surface of a redstone, staining them and darkening them.

The rusted iron lattice screen outside Isa Khan’s Tomb. 

As temperatures rise, the pace of chemical reactions accelerates, resulting in metal oxidation. This eventually causes metallic structures to corrode.

Rainfall events may become more frequent and powerful as a result of climate change.

Excess precipitation can saturate the earth, raising the water table and causing groundwater to rise and permeate through structures and foundations.

This can induce dampness in walls and softening of mud foundations.

The effect of soot, smoke, weathering, and corrosion on Isa Khan’s Tomb’s domed ceiling.

Elevated temperatures, increased rainfall, and more frequent freeze-thaw cycles can accelerate the breakdown of sandstone structures, leading to deterioration, surface spalling, and exfoliation.

The Qutub Minar in Mehrauli, a locality in South Delhi, is a work of Indo-Islamic architecture made of red sandstone and marble.

The Qutub Minar complex has various ancient structures, the most renowned of which is the Qutub Minar. It was erected in the early 13th century by Qutub-ud-din Aibak, the founder of the Delhi Sultanate.

Stages of environmental degradation - the leftmost is relatively intact, the rightmost is significantly disfigured, and the central Alai Minar is in complete ruins.

Unfortunately, our airline sector is extremely carbon-heavy, producing upwards of 90 kg CO2 each passenger per hour, meaning that the Qutub Minar is suffering from sooty depositions, yellowing of its marble, and acid rain.

A central crack in the platform holding up a grave in the Quwwat ul-Islam mosque courtyard.

Temperature changes can cause the sandstone to expand and contract.These repeated expansion and contraction cycles can induce stress within the stone.

Deposits of pollutants like sooty, sulphur dioxide, and nitrogen dioxide accumulate in the interior dome of Quwwat ul-Islam mosque. 

Jama Masjid, located in Old Delhi, is a magnificent Mughal mosque built of red sandstone and white marble.

Constructed between 1644 and 1656, is one of India's largest and most prominent mosques built by the Mughal Emperor Shah Jahan. 

The white marble floors of Jama Masjid, inlaid with black onyx marble, corroding due to weathering, acid rain and exposure to sunlight.

Temperature and humidity changes caused by climate change might jeopardise the integrity of protective coatings or sealants put on stone.

If these coatings fail, the stone will be more susceptible to weathering and discoloration.

Lodhi Gardens, commonly known as Lodi Gardens, holds the tombs of numerous Lodhi dynasty emperors who governed areas of northern India in the 15th century.

The gardens are a tranquil oasis in the middle of the city, with lush foliage, jogging paths, and ancient architecture, making them a favorite destination for both locals and visitors.

A macabre minaret in Lodhi Gardens.

The particulate matter in the air, can settle on the surface of stone due to urban pollution. These contaminants can react with the stone over time, causing chemical weathering and  discoloration.

Algae, lichen, and other microorganisms can develop, especially in wet and shady locations. These development can cause dark staining and blackening of the stone.

A highly perceptible blemish of the paint on the domed ceiling of Sikandar Lodi's Tomb.

Temperature variations may become more pronounced as a result of climate change. This changes can cause paint to expand and shrink, putting strain on the paint film. This tension can decrease the paint's adherence over time, causing to exfoliation.

Iron-containing minerals within the stone can oxidise when exposed to oxygen and moisture.

This process produces iron oxide, commonly known as rust, which can stain the stone brown walls.

Constructed in 1986, The Lotus Temple is a stunning example of contemporary architecture with a lotus flower-inspired design.

The Lotus Temple, is Delhi's Bahá' House of Worship and one of the world's seven Bahá' Houses of Worship.

We are used to thinking of Lotus Temple as being made of flawless white marble, yet for several decades, it has been more like a yellowish grey.

Years of acid rain have corroded the white marble, leaving blemishes, stains, and blotches on its petals.

Lotus petals become yellow owing to oxidation of limestone, weathering, and pollution.

Lacerations on the marble slab because of acid deposition.

The Red Fort, commonly known as Lal Qila is composed of red sandstone and is a superb example of Mughal architecture.

Emperor Shah Jahan built the Red Fort in the mid-17th century and for around 200 years, it was the primary home of Mughal rulers.

The collapsing bastian of Red Fort is constantly exposed to the searing sun, causing extensive UV damage.

Furthermore, the rising frequency of extreme weather events such as high winds, torrential rain, and hailstorms makes these monuments increasingly vulnerable.

The distinctive pietra dura colour work in Mughal architecture; Sections exposed to sunlight clearly more faded.