A recent study published in Nature Climate Change claims that earthworms may be contributing to global warming. The invertebrates join the ranks of humans, cows and dinosaurs as creatures said to have contributed to the planet’s destruction.
The U.K. Guardian has more on the study conducted by researchers from the Netherlands, the United States, and Colombia:
The presence of worms affects how much carbon dioxide is produced in the soil and how much escapes to the atmosphere. Scientists are concerned that earthworms increase greenhouse gas emissions – and that earthworm numbers are on the rise.
Nitrous oxide is another powerful greenhouse gas. Bacteria in the earthworms’ gut produce nitrous oxide and emissions from worm-infested soil can be three times as high as from soil without any worms, the paper says.
For a while, scientists have faced a problem. They know earthworms can increase emissions from soil. But worms can also help the soil store carbon more efficiently, permanently locking it away.
For a while it was unclear whether worms increase or decrease the total carbon emissions from soil – what scientists rather affectionately called the earthworm dilemma.
The scientists in the new study combined all the results they could find to study this question. Overall, they found that the presence of earthworms in soil increased nitrous oxide emissions by 42 per cent and carbon dioxide emissions by 33 per cent. [Emphasis added]
“Over the next few decades, earthworm presence is likely to increase in ecosystems worldwide,” the researchers inform. “For example, large parts of North American forest soils are now being invaded by earthworms for the first time since the last glaciation.”
The worm population is apparently flourishing for a number of reasons, one of which is the switch to more organic fertilizers.
But Ingrid Lubbers from Wageningen University said they still need more time to determine “to what extent global worming leads to global warming.”
The paper concludes with the acknowledgement that earthworms are “largely beneficial to soil fertility,” but “increase net soil greenhouse-gas emissions.”