The Quaternary Period

The Quaternary Period is a period of time that covers the last (approximate) 2 millions years of the Earth. This period is often called the “Age of Humans” although it did see many periods of cooling. At the start of the Quaternary Period the continents had reached just about to where they are now, but further moved to where they are currently. This period experienced ups and downs in regards to “ice ages” or glacial periods and interglacial periods. By around 800,00 years ago a cycle of glacial periods lasting around 100,00 years split with 10,000-15,000 year interglacial years began. Shifting in plates as well as drops in temperature caused sea levels to drop and land bridges to be formed. This allowed the migration of animals and people as well as changed global winds and ocean currents. When temperature rose, so did sea level and everything changed again. This up and down pattern was set up by the cooling trend that the Cenozoic Period saw millions of years before. One theory of Milutin Milankovitch, was that the Earth’s position in relation to the Sun had certain astronomical implications. Further, he theorized that the up and down nature of the changing climate was due to positive and negative feedback systems in the climate system. There are also a theory of Dr. G. C. Simpson’s that says that along with the shifting of the plates, the Earth’s position in relation to the Sun changed ever so slightly, causing an increase in solar radiation. This would then lead to an increase in evaporation and therefore an increase in clouds and precipitation. Recently the climate has been changing more rapidly, as you can see on the figure below where the high’s and lows become more dramatic. With an increase in in carbon emissions due to human activity starting around 190,000 years ago, scientists now believe that humans are playing a huge part in the increase in temperature of the Earth as well as climate change.

Figure 1. Quaternary Period

Image Source: qru.org.uk

This figure shows the up and down nature of the climate for the past 2.6 million years.