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article imagePot industry responsible for significant greenhouse gas emissions

By Karen Graham     Mar 22, 2021 in Environment
Nearly half of the cannabis produced in the U.S. is grown in indoor grow operations. A new study suggests that in certain parts of the country, these indoor grow houses are responsible for significant emissions of planet-warming greenhouse gases.
As more and more states legalize cannabis for medical and recreational use, this has led to a significant expansion of the legal marijuana industry, along with an increase in the use of indoor grow operations.
However, assessing the environmental toll of the ever-expanding cannabis industry is an issue that hasn't been on too many people's minds, according to Jason Quinn, an engineer at Colorado State University and senior author of a study published in the journal Nature Sustainability.
Researchers estimated that the emissions associated with growing 1 ounce of cannabis indoors are about the same as burning 7 to 16 gallons of gasoline, depending on where in the U.S. it’s grown, reports Smithsonian Magazine.
Marijuana plant.
Marijuana plant.
LUIS ROBAYO, AFP/File
What is behind the high GHG emissions?
It takes a great deal of electricity and heating to grow cannabis indoors. We're talking about maintaining optimum temperatures, humidity, and even the need to pump carbon dioxide into the grow rooms to increase plant growth. These requirements account for 11 to 25 percent of facilities' greenhouse gas emissions, according to Science Alert.
However, the biggest energy use comes from the need to constantly pump fresh air from the outside to the growing facilities. This means the air has to be treated so that it is at the correct temperature and has the right amount of humidity. This makes the whole operation very energy-intensive and contributes to greenhouse gas emissions.
The research also showed that depending on where the cannabis grow operations were based, GHG emissions varied. The researchers used the Department of Energy, Environmental Protection Agency, and industry data in determining the amount of GHG emissions growing cannabis indoors created.
Places with more extreme climates and fewer renewables had the highest emissions.
Places with more extreme climates and fewer renewables had the highest emissions.
Jason Quinn
The study shows that higher greenhouse gas emissions are seen in the Mountain West, Midwest, Alaska, and Hawaii compared to grow operations on the Pacific and Atlantic coasts. This is because the climates are milder on the coasts of the United States than inland. It is also because less heating or air conditioning is used and because the electric grids use more clean energy.
The study authors say that "cannabis grown in Southern California has the lowest emissions, at 143 pounds of carbon dioxide equivalent per ounce of dried cannabis. Meanwhile, eastern Oahu in Hawaii has the highest emissions, at 324 pounds of carbon dioxide equivalent per ounce. That's roughly equivalent to burning 16 gallons of gasoline."
Tweed Inc. workers tend to medical marijuana plants at a new commercial operation set up inside a fo...
Tweed Inc. workers tend to medical marijuana plants at a new commercial operation set up inside a former Hershey's chocolate factory, in Smiths Falls, Ontario, an hour's drive from Ottawa, on February 4, 2014
Michel Comte, AFP/File
Why this matters
“Policymakers and consumers aren’t paying much attention to environmental impacts of the cannabis industry,” says Quinn.
“There is little to no regulation on emissions for growing cannabis indoors. Consumers aren’t considering the environmental effect either. This industry is developing and expanding very quickly without consideration for the environment.”
In a commentary about their research in The Conversation, the Colorado State University researchers write that "in Colorado, for example, the weed industry’s greenhouse gas emissions (2.6 megatons of carbon dioxide) exceed those of the state’s coal mining industry (1.8 megatons of carbon dioxide)."
More about cannabis industry, growing indoors, greenhouse emissions, Environmental impact, Carbon dioxide
 
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