This thing called life

This thing called life

The evolution of land plants may have cooled the planet millions of years ago

A recent paper in Nature Geoscience has proposed that when the first simple plants moved onto land, they fundamentally changed the atmosphere by accelerating the weathering of rocks.

The time: the late Ordovician, between 444 and 488 million years ago (but who is counting?). The place: rocks and soil on land, a place previously devoid of plant life. The main characters: moss and other non-vascular plants. Although plants were common in the oceans, the first land plants evolved at this time, spreading across the land and breaking down the chemical components of rocks. The absorption of atmospheric carbon by the new land plants may have chilled the planet sufficiently to induce glaciations.

The British scientists who make this claim considered the geological evidence for climate change at the time and found that it was insufficient to explain the reduction in atmospheric carbon dioxide during that time period. They then conducted laboratory experiments that tested the ability of mosses to enhance chemical weathering. Incubating granite or andesite substrates with moss significantly increased the release of elements such as Calcium, Iron, Magnesium and Phosporus. The release of phosphorus increased productivity in the oceans, where it is the ultimate limiting nutrient. This may have triggered anoxia in some parts of the oceanic environments and created high carbon loads which were deposited as black shales.

Ironically, the environmental changes brought about by the first land plants may have contributed to a mass extinction of marine plants and animals at the end of the Ordovician. That is to say, the new land plants (think moss) may have caused the death of their ancestors (such as algae) in the oceans. I am sure this is not the first time that children have altered conditions such that their parents struggle to cope.

I wonder where else this happens, in life?

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