![]() That was enough to trigger an ice age in the model of Ordovician Earth. When Lenton added this effect of non-vascular plants to a climate model of the Ordovician, the CO 2 dropped from about 22 times modern levels to just eight times modern levels. “The secret seems to be that the moss secrete a wide range of organic acids that can dissolve rock,” Lenton says. After 130 days, rocks with moss living on them had weathered significantly more than bare ones – and about as much as they would have if vascular plants were living on them. ![]() To find out, he set up an experiment to see what damage a common moss ( Physcomitrella patens) could inflict on granite. Lenton suspected they might have played a role nevertheless. Non-vascular plants like mosses don’t have deep roots, so it was thought that they didn’t behave in the same way. The plants’ roots extracted nutrients from bedrock, leaving behind vast quantities of chemically altered rock that could react with CO 2 and so suck it out of the atmosphere. Researchers already suspect that the rise of vascular plants in the Devonian period, some 100 million years later, triggered another ice age. It’s not the first time that plants have been fingered as a cause of glaciation. Tim Lenton of the University of Exeter, UK, and colleagues think the mosses and liverworts are to blame.
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