Photograph by Putu Sayoga, Getty Images
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Sarcophagi burn during a traditional Hindu mass cremation event on August 18, 2013, in Bali, Indonesia.

Photograph by Putu Sayoga, Getty Images

The environmental toll of cremating the dead

As cremation becomes more common, people around the world are seeking greener end-of-life options.

Over the past four years, cremations have surpassed burials as the most popular end-of-life option in the United States, according to the National Funeral Directors Association. At the same time, companies have been springing up touting creative things you can do with a loved one’s ashes, such as pressing them into a vinyl record, using them to create a marine reef, or having them compressed into diamonds.

Cremation—along with these creative ways to honor the dead—is often marketed as a more environmentally friendly option than traditional embalmment and casket burial. Concern for the environment, in addition to economic considerations, may be driving some of the increase in popularity.

“[For] some people, I bet that’s part of it,” says Nora Menkin, executive director of the Seattle-based People’s Memorial Association, which helps people choose end-of-life options.

But while it’s true that cremation is less harmful than pumping a body full of formaldehyde and burying it on top of concrete, there are still environmental effects to consider. Cremation requires a lot of fuel, and it results in millions of tons of carbon dioxide emissions per year—enough that some environmentalists are trying to rethink the process.

The average U.S. cremation, for instance, “takes up about the same amount of energy and has the same emissions as about two tanks of gas in an average car,” Menkin says. “So, it’s not nothing.”

Greener funeral pyres

The particular impact of an individual cremation depends on where and how it’s performed. In India, Hindus have a long tradition of cremating relatives on an open-air pyre. This requires cutting down millions of trees, and the practice contributes to air and river pollution since most pyre cremations occur near water.

The Ganges: Cremation Fires Burn in Sacred City

Hindus believe cremation on the banks of the Ganges River frees the soul from the cycle of death and rebirth.

Since 1992, the nonprofit Mokshda Green Cremation System has been trying to curb this pollution by giving communities access to more fuel-efficient structures for funerary rites.

In these structures, the “pyre” is a metal tray heated with firewood. This setup takes less time and requires less wood than a traditional pyre. It’s also easier to transition from one cremation to another by removing the metal tray filled with ash and replacing it with a new tray containing the next body.

Right now, about 50 such units are spread around nine Indian states. According to Anshul Garg, the director of Mokshda Green Cremation System, one metal pyre can handle around 45 cremations a day. The system also lowers the amount of wood needed from about 880 to 1100 pounds for a conventional cremation to 220 to 330 pounds.

“So, it’s almost less than one fourth of the wood requirement,” Garg says.

Though there has been some resistance to this non-traditional method, Garg says, people are more open to the Mokshda system now than they were in the 1990s. More than 150,000 cremations have taken place on Mokshda pyres in India, saving more than 480,000 trees, averting about 60,000 metric tons of ash from rivers, and releasing 60,000 fewer metric tons of greenhouse gas emissions, according to program officer Chitra Kesarwani.

In addition, Garg says, the nonprofit has received inquiries from other countries in Africa and Asia about making their pyre cremations greener.

In the U.S., by contrast, all cremations happen indoors at crematoriums. The big environmental concerns with this type of cremation are the amount of energy it requires, and the amount of carbon dioxide emissions it produces.

Regional environmental regulations mean that most U.S. crematoriums have scrubbing or filtering systems, such as after-chambers that burn and neutralize pollutants like mercury emissions from dental fillings.

“Most filtration systems are focused on reducing metals and particulate matter and nitrous oxide,” says Paul Seyler, the marketing division manager for Matthews Environmental Solutions, which manufactures cremation technology.

However, these filters do not neutralize the CO2 generated by cremating a body, including the gas generated as a by-product of heating that body up to 1,200 degrees Fahrenheit or more. Matthews estimates that one cremation produces an average of 534.6 pounds of carbon dioxide. Given this figure, Seyler estimates that cremations in the U.S. account for about 360,000 metric tons of CO2 emissions each year.

Back to the earth

For Americans who don’t want to use up so much fuel or release so much carbon dioxide when they die, alkaline hydrolysis may be a more appealing option. Sometimes known as water cremation or aquamation, this way of dissolving a body in water is now legal in at least 18 states.

Alkaline hydrolysis “has about a tenth of the carbon footprint of conventional cremation,” Menkin says. “While the process does take a similar amount of time, it doesn’t have to heat that much, and it’s the water that’s doing most of the work.” In addition, the process releases zero emissions from the body itself.

As with cremation, there are some remains left over after alkaline hydrolysis that families can keep in an urn or scatter in a special location. And the process creates a lot of organic liquid that has some very practical uses.

“Some facilities capture the liquid, and it’s taken away and it’s used on some farmland; it’s an excellent fertilizer,” Menkin says. “But most places, it just goes into the municipal sewer system. And a lot of sewer systems actually appreciate it, because it actually helps with the quality of the wastewater.”

In the future, we’ll probably see many more alternatives to cremation. This year, Washington State became the first in the U.S. to legalize a type of corpse composting called natural organic reduction, or recomposition. Starting in 2020, this process will convert bodies into useful soil that friends and family can either use or donate to the state’s Puget Sound region. And across the U.S., it’s legal to opt for a so-called natural burial, in which the body is allowed to decompose in the ground without added chemicals, concrete, or synthetic materials.

Ultimately, people have to take into account many factors when making funerary preparations, such as how much a certain option costs, whether it aligns with religious and cultural practices, and whether it’s available in a given area. But with more end-of-life options becoming widely available, it’s getting a bit easier to go from ashes to ashes while still being green.

Editor's Note: This story has been updated to correct the consistency of the liquid left over after alkaline hydrolysis; it is not sludgy, as was previously stated.