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In 2011, we published a story that non-native earthworms were a threat to the US as they were releasing more carbon into the atmosphere. Now a new Dutch/US study has revealed that it’s not just non-native earthworms that accelerate carbon release, but ALL earthworms. However, the report, which was published in the Nature journal, states that it is not so much the earthworms’ fault, but the soil in which they live.

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The study, which was written by researchers in Holland, the United States and Colombia, looked at the results of 237 separate experiments from other published studies to explore earthworms’ role in global greenhouse gas emissions and the results were surprising. They discovered that approximately 20% of global carbon dioxide emissions and two-thirds of nitrous oxide emissions came directly from soil due to the large number of natural biological processes that occur in the ground.

The problem is that as earthworms burrow in the soil, they make it more porous. They also interact with the microbes that produce the bulk of carbon dioxide emissions, causing it all to be released into the atmosphere. In short, as the earthworm population grows (which it is), so does the planet’s greenhouse gas emissions. An added drawback is that earthworms produce nitrous oxide in their guts. Overall, the science team found that the presence of earthworms in soil increased nitrous oxide emissions by 42% and carbon dioxide emissions by 33%.

“Earthworms play an essential part in determining the greenhouse-gas balance of soils worldwide,” the report said. “Our results suggest that although earthworms are largely beneficial to soil fertility, they increase net soil greenhouse-gas emissions.”

“Over the next few decades, earthworm presence is likely to increase in ecosystems worldwide. For example, large parts of North American forest soils are now being invaded by earthworms for the first time since the last glaciation”.


Images:  Dodo-Bird and goosmurf