By Becky Oskin
Ants may be some of Earth’s most powerful biological climate brokers, a provocative new study claims.
The average ant lives and dies in less than a year, but a long-term experiment tracking the insects’ effects on soil suggests they cooled Earth’s climate as their numbers grew.
“Ants are changing the environment,” said lead study author Ronald Dorn, a geologist at Arizona State University in Tempe.
Dorn has discovered that certain ant species “weather” minerals in order to secrete calcium carbonate — better known as limestone. When ants make limestone, the process traps and removes a tiny bit of carbon dioxide gas from the atmosphere.
This ant limestone factory is a small-scale version of the massive planetary-cooling process that takes place in the oceans, known as carbon sequestration. Limestones deposited in the ocean hold more carbon than is present in the atmosphere today.
Dorn discovered that ants were powerful weathering agents by tracking the breakdown of basalt sand. At the start of his career, 25 years ago, Dorn buried sand at six sites in the Catalina Mountains in Arizona and Palo Duro Canyon in Texas. Every five years, Dorn has dug up a bit of sand from the sites and measured how much the minerals olivine and plagioclase have degraded from exposure to water, insect activity and chemicals from tree roots.
Dorn’s experiment revealed that ants appear to break down the minerals 50 to 300 times faster than sand left undisturbed on bare ground. At the same time, the ants were gradually building up limestone within their nests. Dorn thinks the ants may be scavenging calcium and magnesium from the minerals and using these elements to make limestone. In the process, the insects may trap carbon dioxide, a greenhouse gas, in the rock. The transformation could take place when ants lick sand grains and stick them on the walls of their nests, but Dorn said the process is truly a scientific mystery.
“We don’t know if they are licking it or pooping it, or if it’s bacteria in the ant’s gut or the fungi growing in the colonies,” Dorn told Live Science.