How Halloween pumpkins contribute to the climate crisis

Pumpkins are methane emitters – a major component of greenhouse gas emissions

It just wouldn’t be Halloween without pumpkins. Every year, billions of bright orange gourds are sold around the U.S., as children and adults alike mark the spooky holiday with some creative carving.

But there’s a sinister side to the fun.

After Halloween ends, people throw their pumpkins away, and they’re hauled off to landfills. Pumpkins in landfills rot — and when they do, those gourds expel gas.

While decomposing, pumpkins and other food waste produce methane, a powerful greenhouse gas that makes up the second-largest percentage of U.S. emissions, behind carbon dioxide.

When a pumpkin reaches a landfill, it decays under other waste as it’s left without oxygen, its orange flesh distorting and breaking down. The bacteria that decompose the pumpkins in this environment create the gas, a process known as biological methane production, which is only done by microorganisms.

The gas that is produced by landfills is about half methane and half carbon dioxide and water vapor, in addition to a small amount of other organic compounds.

Pumpkins sit in a field in Colorado last October. Pumpkins like this one can contribute to the global climate crisis after decomposing in landfills ((AP Photo/Brittany Peterson))

However, methane is at least 28 times more effective than carbon dioxide at trapping heat in Earth’s atmosphere over a century-long period.

While food waste accounts for just under a quarter of municipal solid waste that is discarded in landfills, it also contributes to more methane emissions than any other landfilled materials, according to the Environmental Protection Agency.

Agriculture is the predominant source of methane emissions and methane has accounted for approximately 30 percent of global warming since pre-industrial times, according to the United Nations Environment Programme. The international agency stresses that reducing methane emissions would have a more immediate impact, as carbon dioxide remains in the atmosphere for hundreds to thousands of years and methane only takes about a decade to break down.

Reducing and preventing food waste could address climate change and decrease climate change-related “shocks” to the supply chain, the Department of Agriculture notes.

So, what can pumpkin lovers do to keep more than a billion pumpkins out of landfills? There are many small-scale, sustainable solutions to take this October.

Landfill gas can be captured, converted, and used as a renewable energy source. But, consider composting your pumpkin this year. Those with enough oxygen are able to correctly break down and, potentially, add nutrients to soil for new plants to grow.

Eating pumpkins and pumpkin seeds can also be nutritious, providing a source of vitamin A and potentially reducing cancer risk.

A man holds a pumpkin in his palm at a field in Colorado last October. The U.S. sells around a couple billion pumpkins each year, with many grown in just six states (AP)

Pumpkins, which are largely made up of water, can also be fed to some animals, or donated after use.

The U.S. sells around a couple of billion pumpkins annually, largely harvested in California, Illinois, Indiana, Michigan Pennsylvania, and Virginia. The most recent data from the Department of Agriculture, dated back to two years ago, said these states produced about 1.2 billion pounds of pumpkins in 2022.

Of course, drought and record heat linked to climate change — fueled by methane emissions — can ravage crop yields. Farmers are left with tough decisions about when to cut the pumpkins off the vine or wait until after the fall rush. A hard freeze and the impact of fungus like phytopthora is also a potential risk, and both can lead to pumpkin deterioration.

With reporting from The Associated Press

The Independent will be revealing its Climate100 List in September and hosting an event in New York, which can be attended online.