What is the Ice Age
In popular culture, when one comes across the term “Ice Age” as a term associated with animal migrations in a frozen world. The portrayals have been set in a pre-historic era during some of the coldest time periods of history when thick sheets of ice covered most of the Earth’s surface.
While animated children’s films may pike one's interest in history, it is necessary to understand that the "Ice Age" is not a single moment in the Earth's past. It is, rather, a phenomenon occurring at different moments throughout the planet's lifespan starting from the time when it was believed that the Earth was formed to the present date. This phenomenon is an atmospheric-geological one which lasts centuries if not millenniums and can occur again in the not so distant future.
The following are certain facts one must be clear about to fully understand the Ice Ages:
What is “Ice Age”
The term “Ice Age” may bring our thoughts to a time when mammoths existed. However, according to geologists, historians and scientists, these are separate time periods of ‘glaciation’ stretching as far back as 2,588,000 years in the past from the present date.
Altogether, these glacial periods are called the Quaternary—which includes the Precambrian period (4.6 billion to 541 million years ago), the Permian period (298.9 million to 252.2 million years ago), and other time periods. Among the latest glaciations is the widespread occurrence during the Pleistocene Epoch about 2.6 million to 11,700 years ago and a lesser glacial period which began in the mid-16th century and displayed its intermittent presence for the three centuries that followed.
During these ages, thick layers of ice (even up to 2 kilometers) covered major parts of the planet triggering geographic changes that also caused a change in the organic life forms. Though, compared to geologic and evolutionary time-scale the length of glaciations are short, the evolutionary rate is high during this time.
Geographic changes and sea levels
During the Ice Ages, the geography and atmosphere would experience significant changes. During the Precambrian period and the Permian period, the Quaternary showed signs of glacial erosion which sculpted deep valleys and fjords and large lakes.
By observing the changes in oxygen isotopes, geologists have also noted that the peak of the most recent glacial stage was 18,000 years ago, during which time the sea level was about 120 meters lower than it is today. It has been predicted by the Intergovernmental Panel on Climate Change that global sea levels could rise by 30 to 100 meters in the next century that could completely submerge major coastal regions from the present-day continental map.
Effects on flora and fauna
While specific traits of animals that used to exist during the Pleistocene era, there are stark evolutionary differences of today's creatures to their prehistoric ancestors. Species like the saber-toothed cats and mammoths, which have been made popular through studies and art, are extinct today.
The presence of foliage during historical eras is studied through observing pollen patterns in lakes, fossils and bog sediments. Here, it is found that while animals would migrate in order to adjust to changing patterns in the weather, plants could not do the same, and hence would change their assembly and location depending on the humidity and temperature of the location. In this manner, it has been found that there are many alterations in the abundance of foliage.
The appearance of the first humans
According to scientists and paleontologists, the climate changes that occurred 2.5 million years ago gave rise to the Homo genus after comparatively rapid evolutionary changes from their ancestors- the hominis. Many believe that the major evolutionary pressures came from the shift of forests to drier savanna lands in Africa caused due to glacial changes.
The changes in the human genus included a favor for the upright stance, the ability to walk and run long distances, the ability to grasp, use and make tools. It is also believed that the homo erectus was well established by the time they migrated to eastern and South-eastern Asia about a million years ago during the mid-Pleistocene era.