What is food waste?
Food waste is food that ends up in landfills as unused produce, cooking scraps, or other forms. This includes food that was served but not eaten, or inedible food like fruit rinds and expired products. Food waste is not bad on its own, but it can have significant – and sometimes very harmful – environmental impacts.  

What are greenhouse gases?
Greenhouse gases (GHG) are important chemical molecules – including water vapor, carbon dioxide, and methane – that help keep our planet warm by forming a heat-trapping layer in the atmosphere. The sun’s energy passes through this layer and warms the planet. Some of that extra heat reflects off the planet and passes back through the gases and out into space. By trapping some but not all of the heat, these gases keep the Earth warm – but not too hot – which is how life thrives. This is called the “greenhouse effect.” 

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How do greenhouse gases affect the Earth?
The greenhouse effect creates life-sustaining temperatures on Earth, but recent human activities have led to a problem. Excess greenhouse gases – including carbon dioxide, methane, and nitrous oxide – trap too much heat from the sun in our atmosphere. Under these circumstances, the gases act like a too-thick blanket, causing an overall rise in global temperature. 

These changes to the Earth’s “thermostat” impact other systems as well, creating climate disruptions that impact weather, growing seasons, wildlife, and more. The good news is that we can take steps to limit our greenhouse gas emissions, including composting.

How can composting help limit greenhouse gases?
Composting is a powerful way of limiting one particularly powerful greenhouse gas – methane. Methane accounts for about 10% of global greenhouse gas emissions, but research has shown that it traps around 120 times as much heat as carbon dioxide. 

Landfills are the greatest human-made emitters of methane. Why? When food waste is buried deep within landfills, bacteria must break down the organic material without oxygen, in a process known as “anaerobic decomposition.” This process emits a significant amount of methane. (Click here to find out more about how we quantify methane emissions from landfills.)

Backyard composting, on the other hand, breaks down food in an oxygen-rich environment, which does not produce methane. And that really helps!

How else does composting sustain our Earth?

Great question! Check out this infographic from the EPA to find out more:

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