What happens to an apple when you throw it away? I always thought throwing food scraps into the trash was no big deal – it would just decompose in the landfill, no problem, and be gone. And isn’t rotting just about the most natural process in the world?
Turns out that’s not really what happens. Things get compacted in the landfill – big time. This means there isn’t enough air for organic matter (food, yard waste, and poo) to decompose like they naturally would – say, on the forest floor, or in the backseat of your car (where Phil throws his chewed out apple cores… just kidding. He hasn’t done that for at least 2 months). Instead, they go into anaerobic decomposition. This type of decay involves a different set of microorganisms that release methane gas.
Now, methane gas is interesting for two main reasons. First, it is highly flammable and plays a big role in starting and intensifying landfill fires. According to a FEMA 2002 report, 8,400 landfill and dump fires are reported to the fire service in the US every year – likely many more go unreported. Actually, it seems that landfill fire extinguishing can be a pretty profitable business.
The second interesting thing about methane is that it is an extremely potent greenhouse gas – one molecule of methane gas (CH4) is 21x more efficient at trapping radiation from the sun than carbon dioxide (CO2). While methane is produced naturally (from sources like wetlands), over 60% of all methane emissions globally come from human activities with landfills responsible for 6-13% of this.