Sunspots are one possible cause for the LIA.
	Up close view of sunspots on the sun's surface. Credit: Soho (ESA & NASA)

So What Caused the LIA?

Some researchers have looked to the sun for possible causes of the LIA. Sunspots — temporary dark areas of highly concentrated magnetic fields on the sun's surface — are one possible sign. When there are more sunspots, there's more activity and more heat produced by the sun. Sunspot variations may coincide with major changes in Earth's climate. For example, between 1645 and 1715, during one of the coldest spells of the LIA, there was an unusually low number of sunspots.

Volcanic eruptions can also influence climate by injecting a veil of sun-blocking ash into the atmosphere. There is circumstantial evidence that volcanoes could have triggered the LIA. The quietest period of volcanic activity was from 1100 to 1250, which matches with the MWP, while the most active period came between 1250 and 1700. In 1815, the eruption of the Tambora volcano in Indonesia pumped huge amounts of ash into the atmosphere. The following year has been referred to as the "Year Without a Summer," when New England and northern Europe experienced frost and snow during June and July.

A Silver Lining

Volcanic ash in the atmosphere may have helped cool the climate during the LIA. Credit: USGS

Though the colder climate made life very difficult during the Little Ice Age, Europeans slowly learned to adapt to the harsh conditions and benefited from the changes they made in order to survive. The abundant fishing grounds of the Newfoundland Banks are thought to have been discovered in the late 1400s while fishermen were searching for vanished fish stocks. Years of failing harvests pushed Flemish and Dutch farmers to develop new farming techniques such as extensive fertilization, building simple windmills to improve drainage of the land, and rotating crops to keep the soil rich — their innovations are still used today throughout northern Europe.

	The potato soon replaced cereal grains as a staple in the northern European dietCredit: USDA

In addition to new farming methods, new, hardier crops were introduced. During the LIA, Spanish conquistadors returned from South America with potatoes grown by the highland Andean Indians. The environment of northern Europe at this time was as cool and damp as the Andean homeland, which allowed potatoes to grow successfully. The potato soon replaced cereal grains as a staple in the northern European diet and nutritional diseases began to decline throughout Europe by the late 18th century.

'Hunters in the Snow' by Pieter Brueghel. Credit: Kunst Historic Museum, Vienna, Austria.

The cooler climate also inspired many works of art and literature. Painters such as Pieter Brueghel and Adriaen van de Venne recorded chilled landscapes. During a cold summer holiday in 1816 at Lake Geneva, Switzerland, Mary Shelly was inspired to write her novel "Frankenstein" — complete with a glacier-set showdown and an icy climax.

It took a long time — and a lot of suffering — before people adapted to the LIA climate. And human beings weren't the only ones affected. The LIA challenged ecosystems in the natural world. Animal and plant distributions shifted as conditions changed. The LIA can be viewed as a cautionary tale — just a few degrees shift in temperature led to large changes in the world around us. How well could we adapt today?

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