Earthworms aren’t just good at making soil; they’re also proficient at unlocking greenhouse gas emissions from their dirt meals. While worms likely won’t bring on a global warming catastrophe, the Guardian writes, they do play a larger role in greenhouse gas emissions than scientists previously thought.
In a new Nature Climate Change study, researchers sorted through 237 different worm studies conducted around the world to figure out the creatures’ role in greenhouse gas emissions. It’s been known for awhile that earthworms have a role both in producing greenhouses and in limiting the amount of these gases that makes it into atmosphere. The Guardian explains:
Worms can increase emissions of one greenhouse gas while reducing emissions of the other, the study says. Ideally, to work out the overall impact, scientists need experiments that look at both gases at the same time.
Worms, the study noted, can “stimulate carbon sequestration in soil aggregates”—increase the amount of greenhouse gas the soil is able to keep locked down. But worms also produce nitrous oxide—another powerful greenhouse gas—in their guts. Worm-infested soil can have concentrations of nitrous oxide up to three times as great as soil without any worms.
The study found worms increase nitrous oxide emissions by 42 percent and carbon dioxide emissions by 33 percent. But the increased carbon sequestration helps balance than increase out: overall, the worms only increased “the global warming potential of soils by 16 percent,” the Guardian reports. While earthworms benefit soils, they do play a significant role in greenhouse gas emissions worldwide, the researchers conclude.
Worm impacts, though very small when compared to those produced by humans, are likely to intensify in the future. Worms are on the rise, the authors write. Some North American soils are being invaded by the squirmy animals for the first time since the last glaciation, for example. Organic fertilizers will only expedite this process.
Before any human readers get smug and start finger-pointing at the worms, however, the Guardian reminds:
Despite the efforts of the humble earthworm, the vast majority of carbon dioxide in the atmosphere – which is responsible for 60 per cent of the total warming from greenhouse gases – is caused by human activities such as burning fossil fuels and deforestation.
More from Smithsonian.com: