Right after I posted my question I googled "Little Ice Age" to find out more about this. I had never heard about the little ice age, much less what may have caused it. Seems the "experts" are mixed about whether or not it was a phenomenon or part of a natural cycle. There is also some discussion about whether there was an "ice age" worldwide or just in the northern hemisphere and even if it was primarily in Europe and it is European ethnocentric thinking that turned it into a worldwide event.
Anyway, here is what two sites had to say about possible causes of the Little Ice Age:
Scientists have identified two causes of the Little Ice Age from outside the ocean/atmosphere/land systems: decreased solar activity and increased volcanic activity. Research is ongoing on more ambiguous influences such as internal variability of the climate system, and anthropogenic influence (Ruddiman). Some have also speculated that depopulation of Europe during the Black Death and the resulting decrease in agricultural output may have prolonged the Little Ice Age.
One of the difficulties in identifing the causes of the Little Ice Age is the lack of consensus on what constitutes "normal" climate. While some scholars regard the LIA as an unusual period caused by a combination of global and regional changes, other scientists see glaciation as the norm for the Earth and the Medieval Warm Period (as well as the Holocene interglacial period) as the anomalies requiring explanation (Fagan).
Link:
http://en.wikipedia.org/wiki/Little_Ice_AgeAmong the possible reasons given for the "Little Ice Age" are low solar activity and increased volcanism. How then are we going to tell which part of the recent warming is "natural" and which (if any) is due to human influence? The standard answer to this question is that the warming right after 1850 is mostly natural. The weather in the mid- and late 1830s was highly unusual and highly stressful, with severe winters and bad harvests (The great Irish famine falls into this period.) In the conventional view, the "Little Ice Age" is an anomaly (indeed it was the coldest period in the last several thousand years) and the warming after 1850 simply gets us back on track. This concept also supports the idea that warming in the last century has been a good thing for people, plants and animals, because it brought back the previous regime of a more benign climate.
It is difficult to argue with this conventional view, but we must be aware that it is simply a convenient assumption: no more, no less. There is nothing in our understanding of climate that would forbid a continuation or worsening of the "Little Ice Age" conditions after 1850 and right into the present. On the contrary, the long-term view of climate change — the one that includes the coming and going of ice ages — actually demands increased cooling for the last 3000 years or so. That the Earth has come out of the "Little Ice Age" is much more in need of explanation than the fact that it got into one.
Link:
http://calspace.ucsd.edu/virtualmuseum/climatechange2/04_3.shtml
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