The carbon cycle is one of the key processes that helped life emerge on our blue planet. The carbon cycle is the movement and exchange of carbon atoms across the atmosphere, ocean, plants, organisms and land. Working as a “natural thermostat,” the carbon cycle has been regulating the Earth’s temperature over long periods of time.
However, this key life cycle that we see today is different from how it used to be about 400 million years ago. Scientists at the University College London and Yale University have found in a new study that the carbon cycle changed dramatically about 400 million years ago, leading to a “seesawing” climate. The major shift caused a cooler planet with alternative warm periods and ice ages. Before this shift, the atmosphere had a concentration of carbon dioxide much higher than it is today and as a result of the greenhouse effect, the climate was much warmer. One of the key findings of the research is that plants’ colonisation of the land played a central role in causing this shift in the carbon cycle.
The shift “appears to be linked to two major biological innovations at the time: the spread of plants on land and the growth of marine organisms that extract silicon from water to create their skeletons and cells walls,” said Philip Pogge von Strandmann, the senior author of the study in a statement. The NASA-supported study was published on July 14 in Nature.
Scientists believe that before land-based plants triggered the cold-warm cycle of the earth’s atmosphere, this cyclic change is what accelerated the evolution of complex life forms. As a result, land-based animals formed for the first time.
Scientists took 600 rock samples from different locations across the world and analysed them for Lithium isotopes. Their analysis indicated that the formation and expansion of plants on land coincided with a major shift in clay production. Moreover, land-based plants drew carbon dioxide from the atmosphere and did not eventually release it back even when they decayed.