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A familiar answer to the question, “How much is one ton of CO2?” might sound something like this: “One ton of CO2, that’s like half an elephant, right? Wait, isn’t CO2 a gas? How does that even work?”

I just learned that in 2005 the average coal-fired power plant in the US emitted 4,643,734 metric tons of CO2 (epa.gov). That’s right, those are all commas. 4.6 million metric tons of CO2. I mean, that’s like 2 million elephants. Right?

The problem is we don’t really know, not intuitively. No one can picture what 4 million tons of CO2 really looks like, even some of the most mathematically savvy environmentalists. So with talks of energy audits and greenhouse gas inventories, how do we bring it all down to scale? How can we internalize how much 4.6 million metric tons of CO2 is? I’m honestly not sure we ever really can. 4.6 million is a huge number.

Unfortunately, unless we are able to understand and conceptualize the costs of our actions to the environment, sustainable practices won’t become habits. Doing a ghg inventory is a commendable and necessary step towards reducing the environmental impact of your school or business but unless students and employees understand the true cost of their actions and choices, only so much can be accomplished.

So, just how much is 4.6 million metric tons of CO2? According to the EPA, that’s the same as the annual energy use of 422,542 homes. It’s the same as the annual ghg emissions of 850,501 passenger vehicles. It’s also the amount of carbon sequestered annually by 32,390 acres of forest preserved from deforestation (epa.gov). These equivalents go a little way in helping understand the scales we’re talking about when we discuss “emissions.” They’re still large numbers but at least they’re familiar. Unlike carbon or other greenhouse gases, we can all picture a large number of houses, cars or trees.

Hopefully, most institutions will never have to explain how much 4 million metric tons of emissions are. But if you do need to illustrate how much, say, 70,000 metric tons of greenhouse gas is, here are some resource that might help.

Emissions Calculators (into familiar equivalents)

Environmental Protection Agency – Emissions Calculator (used for the calculations in this blog)

Personal/Household Emissions Calculators (estimates of use)

CO2 Science – Greenhouse Gas Reporting Calculators (list)
Environmental Protection Agency – Household Emissions Calculator
UC Berkeley – Cool Climate Emissions Calculator

X amount of CO2 Is the same as…

California Climate Change – Conversion of 1 MMT CO2 to Familiar Equivalents
eartheasy – The One-Tonne Challenge
Environmental Defense Fund – Picturing a ton of CO2