Most earthworms may be tiny, but a new study suggests their
impact on the climate could be mighty. Researchers had long
assumed the creepy crawlers help store carbon in soils by
consuming fallen leaves and other decaying plant matter, which
they deposit in soil in their cast, or droppings. But newer
studies suggest the worms may actually increase soils' output of
two key greenhouse gases, carbon dioxide and nitrous oxide. A
new meta-analysis, published Sunday in the journal Nature
Climate Change, found that the presence of earthworms appears to
increase soils' output of CO2 by 33 percent and of nitrous oxide
by 42 percent. A bowl of exotic European earthworms species
federal scientists recently found in National Wildlife Refuge
sites throughout the Upper Midwest. Credit: Lindsey
Shartell/U.S. Fish and Wildlife Service "We've known for only a
couple of years that they can really increase nitrous oxide
emissions, but it was not really clear how much," said study co-
author Jan-Willem van Groenigen of Wageningen