No one can say exactly when the next ice age will occur, but we can look to previous ice ages and see what caused them. Learning about what caused the previous ice ages, scientists can possibly know when the next ice age will happen again.
What Causes an Ice Age?
There have been major ice ages or glacial periods in Earth’s history. An ice age can begin as the overall temperature of the planet cools and the winter snows don’t melt over the summer. The snow continues to build up with each winter and again each summer not all of the snow melts, getting deeper each year.
More snow on the ground will reflect the warmth of the sun, causing further cooling; this is called the albedo effect. Each winter the snows build up and each summer more snow fails to melt.
The snow then compacts and becomes so heavy that it causes it to move in the form of glaciers. As more snow and ice cover larger parts of the planet, the albedo effect becomes more pronounced causing even further cooling.
Previous Ice Ages
Scientists now believe there have been four major ice age periods in Earth’s past. The earliest well-documented ice age occurred about 700 million years ago when the entire earth could have been covered with ice, called snowball earth.
And ironically, what ended this major ice age was global warming in a sense, the greenhouse effect from volcanoes.
Scientists don’t know exactly what caused these ice ages either, there is speculation that maybe the oceans were warmer causing more evaporation, causing more cloud cover and precipitation which built up the snow pack.
There are the glacial (glaciers advancing) periods and interglacial (glaciers retreating) periods. The planet has seen this cycle of glacial and interglacial periods on a time scale of 40,000 to 100,000 years. The Earth is currently in an interglacial period and has been in this period for about 11,000 years now.
What is the Initial Cause of an Ice Age?
There are several theories as to what causes an ice age to start including:
- The composition of the atmosphere, concentrations of carbon dioxide, CO2
- The Earths orbit around the sun. The Earths orbit changes with what’s known as the Milankovitch cycle
- The suns orbit in our galaxy and the suns energy output
- Changes in ocean currents, which affect our weather
- The moons orbit around the Earth
- The impact of a large meteor
- Large volcanic eruptions
The Little Ice Age
In the recent past, there have been times when the earth cooled significantly. What is known as the little ice age lasted from 1350 to 1850; peaking in the 17th century, though the time duration is argued.
During this time, the average temperature fell by 2-3˚ F (1-1.5˚ C), winters lasted longer, crops didn’t grow and there was famine. Other historical events during the Little Ice Age include the dark ages, the black plague and the terrible winters during the American Revolution.
There is much discussion as to what caused this little ice age, and no one seems to be able to pin point any one cause. Increased volcanic activity could have been the cause, but there have been increases in volcanoes before and after, that didn’t cause a little ice age.
One fact that does stand out during this time period was that the sun was in an unusually quiet stage. Usually there is a normal 11-year cycle for sunspots, going from no sunspots to many sunspots.
During this time, there was a 50 to 70 year period when there were no sunspots. This is called the Maunder Minimum.
The Year Without a Summer
Near the end of the little ice age, the summer of 1816 has gone down in history as the “year without a summer”. It snowed during the summer in New England and the weather was gloomy across the planet and colder then normal.
This part of the little ice age does have a known reason or cause and that was the major eruption of Mt. Tambora in Indonesia on April 5, 1815. It erupted for four months and was the largest volcanic eruption in history. The ash and smoke layer around the planet caused the cooling.
In 1991, Mt. Pinatubo in Indonesia erupted; it was the second largest eruption in the 20th century and the largest stratospheric disturbance since Krakatoa, throwing out 30 trillion pounds of rock, liquid dust and gas into the atmosphere.
The years of 1992 and 1993 were cooler in the interiors of the continents and weather patterns changed.
Since January 2009, there have been swarms of earthquakes in Yellowstone National Park in Wyoming. In prehistoric times Yellowstone has erupted with 1,000 times more power then the 1980 eruption of Mt. St. Helens. Scientists say it is now 40,000 years overdue for an eruption. Will that cause the next ice age?
When Will the Next Ice Age Occur?
That might be impossible to know, especially since scientist still don’t know what caused other ice ages. Ice ages start slowly and gradually over a long time.
The last major ice age might have been caused by changes in the earths CO2 levels or it could have been caused by a minor shift in the earth’s axis.
Although a cataclysmic event such as a large meteor hitting the earth could cool the planted drastically and suddenly. A major volcanic eruption or series of them could also cause another ice age.
Sudden shifts in the ocean currents would shift our weather patterns dramatically, which could cause an ice age. Some scientists believe we are overdue for an ice age, but human activities could have stalled it or possibly even eliminated that cycle.
Scientist can predict the earth’s orbit in the past and in the future, according to that school of thought, the next ice age will begin in about 50,000 years. As more studies of ice cores are done, scientist will find new information concerning previous ice ages and may be able to predict the next one.
Copyright © Sam Montana 2009-2016
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