Composting increases carbon emissions instead? A situation most people don't know about?

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Update time : 2025-06-19

Is the environmental myth of composting busted?

In recent years, composting has been widely touted as the ultimate solution to “zero-waste living”. However, under the wrong conditions, composting can produce more greenhouse gases than landfills and even exacerbate climate change, according to the latest scientific research.

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In 2024, a UC Berkeley study found that:

30% of home composting systems actually increase carbon emissions due to mismanagement

Some “compostable plastics” emit methane (CH₄), which has a greenhouse effect 25 times greater than that of CO₂, in an oxygen-poor environment.

Part 1: Why does composting increase carbon emissions?

Scenario 1: Anoxic composting (methane production)

✅ Healthy composting (aerobic decomposition):

Microorganisms convert organic matter to CO₂ + water + humus

Carbon emissions: 0.1kg CO₂e/kg compost

❌ Anoxic composting (anaerobic decomposition):

Anaerobic bacteria dominate, methane (CH₄) is produced

Carbon emissions: 2.3kg CO₂e/kg compost (23-fold jump)

Common mistakes:

Compost bin completely sealed

Material too wet and not turned

Scenario 2: Incorrect material mixing (contaminated soil)

Type of material Problem Alternative

Industrial grade PLA plastic Does not decompose in home composting Recognize OK Compost HOME certification

Meat/dairy products Produces odor, attracts pests Bokashi composting only

Herbicides residues on plants Poison beneficial microorganisms High temperature composting treatment alone

Test case:

A family put “ industrial grade PLA” tableware into the compost after 6 months and detected microplastic residues that contaminated the entire batch of compost. A family composted “Industrial Grade PLA” tableware, and after 6 months, microplastic residues were detected, contaminating the entire batch of compost.

Scenario 3: Low temperature composting (cannot inactivate pathogens)

Ideal temperature: 54-65°C (lasts for 3 days to kill pathogens/weed seeds)

Reality:

Small compost bins are only 30-40°C

Undecomposed pathogens enter the soil with the compost

Research data:

Soil Association tests in the UK have shown that 42% of home composts contain E. coli in excess of the limit.

Scenario 4: Centralized treatment over long distances

Centralized composting plant:

Trucks are needed to transport the waste, generating 3.2kg CO₂ per tonne

Decentralized local composting:

Carbon emissions are reduced by 80%

Typical case study:

A city has introduced centralized composting of food waste, but because of the long distances involved in transporting the waste, the carbon footprint has exceeded that of landfill.

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