The Little Ice Age is not a global phenomenon, but would mean a low glacial period marked by an expansion of glaciers in the modern era, between the 13th and 19th centuries, particularly in France.
The LIA is a cold climate period occurred in Europe and North America from the 1300s until the 1850s.
The Little Ice Age corresponds to several minimum mean temperatures very clear on that time. In Europe, this phenomenon is accompanied by a series of bad harvests, famine and natural disasters. The exact beginning, the Little Ice Age is quite vague. The Little Ice Age recorded in Europe gives no indication of the beginning of this mini ice age because generally, climatic variations are still lagging behind several decades in Western Europe compared to Greenland. Given the difficulties in estimating these episodes of cold, the limits of the LIA vary between studies.
Studies of the Laboratory of Glaciology and Environmental Geophysics, University of Grenoble and the Laboratory of Glaciology and Geophysics of the Environment of the Federal Polytechnic School in Zurich, suggest that glacial extensions are due to a significant increase precipitation, but to a significant drop in temperatures.
The big freeze would be the consequence of the increase over 25% of winter snowfall.
Since the end of the Little Ice Age, dating back almost 150 years, the retreat of glaciers is almost continuous.
The glaciers have lost about a third of their total volume, the average thickness decreased by 30 cm/year over this period.
Image: The frozen Thames in 1677.
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There is no scientific consensus on the dates and causes of the Little Ice Age.
For some scientists, the causes of the Little Ice Age would be lower solar radiation. Others explain the phenomenon, by volcanic eruptions which have slightly obscured the atmosphere.
A study presented in the journal Geophysical Research Letters by Gifford Miller of the University of Colorado, explains that the Little Ice Age would have begun precisely between the years 1275 and 1300.
Four volcanoes, in the space of fifty years, would be responsible for this phenomenon. Of volcanic dust which reflect solar radiation, in a sustainable manner, actually decrease the overall heat received by the Earth's surface.
The U.S. National Center for Atmospheric Research (NCAR) has developed a climate model to test the effects of repeated volcanic eruptions, a period of fifty years. The cumulative effects of discharges would give birth to the Little Ice Age. Cooling, expansion of sea ice, changes in water circulation and reduced heat transport to the Atlantic coast, this is the likely scenario, according to NCAR, this Little Ice Age.
But the Little Ice Age is not comparable to long and intense periods of glaciation of the Earth's history.
There are about 750 million years, Earth would have passed through ancient times as a cosmic ball of ice, as at present, Tethys or Rhea, Saturn's moons, or Europe, the moon of Jupiter.
On every continent, our planet has kept the traces of its past glaciation when the ice seems to have covered almost the entire planet.
This theory is known as the snowball Earth.
The causes of major climatic event, are not well known, yet it is after this event that multicellular organisms have appeared on Earth.
Two teams from the CNRS and CEA have successfully modeled across the million years, the evolution of the carbon cycle, climate and position of continents, quantitatively explaining this glaciation.
Ice sheets and sea ice had reached the equator as indicated by glacial features, found on all continents.
The assumption made by these experts, is a decrease in the concentration of CO2 in the atmosphere.
When the critical threshold is reached, it triggers a sudden cooling.
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Image: There are about 750 million years, Earth would have passed through ancient times in the form of cosmic snowball (artist image).