Little Ice Age | Universe Today

Written by John Carl Villanueva

The Little Ice Age is a period of cold temperatures that followed after what is known as the Medieval Warm Period. The different places in the world did not cool down simultaneously and, in fact, some of the largely affected areas have different start and end dates. The earliest recorded start date was in 1250, when the Atlantic pack ice started advancing. The prevailing consensus is that the Little Ice Age ended sometime within the 19th century.

There are four suspected causes of the cooling period: decrease in solar activity (more popularly referred to as the Maunder Minimum), increase in volcanic activity, shutdown of the great ocean conveyor, and anthropogenic effects.

The Maunder Minimum is a 70-year period of sunspot inactivity which is believed to have coincided with the coldest stretch of the Little Ice Age. During this period, power output from the Sun stayed unusually low much longer than the typical 11-year cycle of maximum and minimum solar power outputs.

During the Little Ice Age, records show that the Earth had an increase in volcanic activity. Volcanic ash that was ejected to the sky may have obstructed heat coming from the Sun and subsequently caused the cooling. One event supporting this theory is the 1815 eruption of Indonesia's Tambora. What followed was a summerless year wherein snow was reported to have fallen in June and July in Northern Europe.

The Gulf Stream or the Great Ocean Conveyor is one of those highly responsible for holding the balance in the Earth's climates. The Medieval Warm Period may have caused some frozen fresh water to melt and pour into the North Atlantic, causing the Gulf Stream to shutdown. When it did, the climate balance was disrupted.

Anthropogenic effects refer to those effects that are brought forth by human activity. Since a huge portion of the Little Ice Age was preceded by the Black Death, wherein probably up to 60% of Europe's population perished, some people believe the substantial drop in agricultural activity allowed forests to grow unhindered. This subsequently resulted in a drop in atmospheric carbon dioxide.

As many of you may have learned from Al Gore's documentary, An Inconvenient Truth, the rise and fall of carbon dioxide levels coincides with the rise and fall of the Earth's temperatures. Hence, if temperature rises when CO₂ levels rise, temperature drops when CO₂ levels fall.

Find out more about the Maunder Minimum here in Universe Today. Care for a read bearing bleak predictions? How about an article that claims Global Warming is irreversible?

Articles related to the Maunder Minimum brought to you by NASA and Physics World, here are the links:
The Sun's Chilly Impact on Earth
Where are the sunspots?
Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste:
The Sun, Spots and All
Dangerous Solar Flares, Higgs Boson Insights, and Light Speed Flashlights

Filed under: Astronomy

Tags: global warming, Little Ice Age, Maunder Minimum