Global ice ages in Earth’s history occurred at a sharp change in the level of solar radiation for a short period of time. These are the results of modeling conducted by American scientists, reports the journal Proceedings of the Royal Society A.
In Earth’s history there were at least two of such period in the Paleoproterozoic 2.4 to 2.1 billion years ago during the Neoproterozoic 850-630 million years ago. Scientists from mit have analyzed several scenarios, in which as the main drivers universal cooling have considered the levels of incoming solar light and carbon dioxide in the atmosphere.
The authors believe that the sharp decline in solar radiation reaching the surface, could be related to mass eruption of volcanoes, or with the formation of biologically induced cloud that blocks the sunlight. In both situations, the planet cools and the ice zone to expand.
However, the increased albedo – the reflectivity of the Earth’s surface. Thus, more reflected sunlight, not warming the planet. The cooling process is accelerated, while the ice did not cover it all.
In this case, weathering is much reduced and the carbon dioxide accumulates in the atmosphere, creating the greenhouse effect. He eventually removes the planet from the ice age.
Experts have developed a simple mathematical model of the Earth’s climate system and found that much of the speed reducing incoming solar radiation – a more important parameter than the size of the stream. According to the authors, the Earth should experience approximately a two percent drop in incoming sunlight for ten thousand years to return to a global glacial period. Scientists believe that their findings can be extended to exoplanets, located in a potentially habitable zone.
In March, research by NASA showed that the ice packs in the deepest land gorge in the world – canyon Denman in East Antarctica has started to melt. Experts have found that the glacier is strongly influenced by warm ocean water. Although the bottom of the gorge lies at a depth of 3500 meters below sea level, melting ice could trigger an increase in its average level by half a meter.
The researchers are not ready to fully predict the process of liberation of the canyon Denman ice due to its specific geographical position. However, some trends are evident now, they added.