In a paper published today we demonstrate how the first land plants (which were something like modern-day moss) could have had a significant effect on global temperature and atmospheric carbon dioxide. Moss was grown on a series of different rock types (Indonesian Basalt the pics below) and we found that in the process of growing the mosses weathered the rocks i.e. they released elements locked up in the rocks. Some went into the moss and some into the water which was in the microcosms the experiments were done in. As well as weathering of elements which are essential for plant growth in substantial amounts (Iron and Phosphorous), other elements which play an important role in the balance of carbon dioxide between the ocean and atmosphere were released. These alkaline earth metals change the balance of carbon chemistry in seawater and lead to uptake of carbon dioxide from the atmosphere. At the time when the first moss-like plants colonised the land surface, about 450 million years ago, there was a series of deep glaciations where global temperatures dropped substantially. It was previously though that the small rooted mosses couldn’t perform significant rock weathering and thus couldn’t be responsible for these glaciations through driving ocean uptake of carbon dioxide. This paper suggests that it may indeed have been the cause.
Photos courtesy of Mike Crouch / Andrew Davis / John Innes Centre
Also, we made slashdot 🙂
Oh, and this Continuing their CO2 fixation scientists now claim plants cause ice ages (junkscience.com)