EMISSIONS

A burning question: the climate impact of 7 million funeral pyres in India and Nepal

Could South Asia be contributing to climate change in death as well as in life?

According to a new study, the traditional Hindu ritual of burning the dead on funeral pyres consumes 50 million to 60 million trees in India and Nepal annually. That and the combination of camphor, clarified butter and synthetic powders burned along with the body are responsible for a large chunk of a light-absorbing aerosol known as brown carbon.

Unlike black carbon aerosols spewed from the incomplete combustion of fossil fuels and biofuels, brown carbon does not typically show up in greenhouse gas inventories. But according to the authors of the study of cultural burning practices, published last week in Environmental Science and Technology Letters, that needs to change.

"Most of the emissions inventories which are being published for South Asia and utilized in climate models are basically dictated by the standard fuels that we in Western countries find most prevalent. But if you are from Asia, it's kind of obvious that there are so many other sources which go unnoticed," said Rajan Chakrabarty, an assistant research professor at the Reno, Nev.-based Desert Research Institute.

Chakrabarty and Shamsh Pervez, a professor of chemistry at the Pandit Ravishankar Shukla University in India, said they knew they wanted to understand the significance of those other sources and decided to start with the most relevant: funeral pyres.

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According to census figures, more than 7 million people are burned every year in India and Nepal, part of a Hindu funeral rite that holds that the body must be destroyed to force the soul to separate from it.

Big impact on regions

The typical burning, the study notes, is "a scripture-based ritual without much variation in the amount and types of solid feedstock used." The typical pyre is constructed of 550 kilograms of wood, and a few kilograms of biological and synthetic materials including cow dung, rice grains, vermilion powder, camphor and clarified butter. Once the corpse is placed on the pyre, the burning takes four to six hours.

Using that model, the scientists sampled plumes from seven ceremonies to study particulate and gaseous carbon emission rates in one central Indian province. They found that the emissions from funeral pyres were the equivalent of about 23 percent of the total carbonaceous aerosol mass produced by the burning of fossil fuels and 10 percent of the emissions produced by biofuels in the region.

"Our findings underscore the importance of accounting for cultural burning practices as aerosol sources in emission inventories and [brown carbon] aerosols in climate models, as well as the development of mitigation strategies," the paper says.

How much brown carbon influences climate change remains understudied, both scientists said. Chakrabarty noted that black carbon, commonly known as soot and produced by burning fossil fuels and biofuels like wood and dung, is considered as important as greenhouse gases over South Asia. Last year, a landmark study found black carbon has more than twice the climate impact reported in previous assessments, ranking as the second-largest man-made contributor to global warming. The study of funeral pyres, they note, finds that in addition to black carbon, brown carbon aerosol emissions are also taking place in large scale over Asia.

And yet, what can or should be done about cremation pollution? Chakrabarty said, "I honestly don't know." He noted that so sensitive are Hindu funeral rituals that many families denied him and his colleagues permission to watch and study the burning.

An 'existential question'

"It was an emotional ceremony, and they didn't want anything to meddle the flow," he said. The emotion attached to cultural burning practices, he said, is somewhat like the traditions that until only recently bound many families to dirty cookstoves -- only far more visceral.

"It's an existential question," Chakrabarty said. "If you stop this, you will be doing a lot for the environment. But nobody knows what happens after life. Anyone who is Hindu knows how important this is."

Pervez said he believes the only solution is to switch from cremation to burials. The study also recommends that because funeral pyres are so deeply entrenched in the culture, wooden ones might be replaced with more eco-friendly pyres.

"We have to stop [or] minimize burning practices in ritual and religious activities," Pervez said.

The investigators weren't deterred by the touchy nature of their research. The scientists' next step, they said, is to study the impact of burning incense and other materials in millions of South Asian temples.

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