During the time of the Ice Age, natural thermostat prevented the Earth to be frozen. The atmospheric CO2 concentrations hit over a range of 100 ppm or parts per million, by volume. The process behind the variation has been quite difficult to pinpoint, but it is known that the alternation in the storage of the carbon by photosynthetic organisms plays an important role.
A researcher from the Institute of Environmental Science and Technology who is also the co-author of the study, Sarah Eggleston mentioned that "When we took a close look at measurements from ice cores, we noticed that atmospheric CO2 concentrations hovered close to 190 ppm during much of the past 800,000 years, but very rarely fell any lower."
She added that it was surprising because the measurements suggest that the very low CO2 concentrations were stable. Furthermore, the researchers were aware that the CO2 was soaring high at the distant geological past, but there is zero evidence that the CO2 concentrations were ever lowered the 190ppm, according to Science Daily.
As follows, a professor from the ICREA at ICTA-UAB who is the study's lead author Eric Galbraith said that "We know that, over hundreds of thousands of years, CO2 is regulated by slowly reacting with exposed rocks. But this would be too slow to explain the stability during periods of only a few thousand years, as we see in the ice cores. So it must have been some other mechanism that kicked in at very low CO2."
Thus, the study that has been published Nature Geoscience, the authors suggest that it was most likely the biosphere or the natural thermostat maintained the temperature that is habitable since, at very low CO2 levels, the phytoplankton and plants struggle to photosynthesize. The slower growth of the organisms would cause less carbon in the soils and deep ocean which leaves more in the atmosphere and prevents the CO2 concentration from falling further, according to EurekAlert.
In line, the natural thermostat could have prevented the extreme cooling that would have led to a freezing of the Earth and have caused it to be a "snowball." However, the study did not reveal any corresponding regulation during the warm portions of the ice age cycles. It suggests that the Earth does not have the same mechanism to prevent rapid warming.
