The clearest impacts of climate in the historical past that I'm aware of took place when the climate of western Europe warmed from the early 1700s to about 1739. There were a number of good harvests in Britain and Ireland and our population increased dramatically as more children survived. You should now see why your premise about the Little Ice Age is completely wrong. The 1730s temperatures in the UK are exceeded by two decades - the 1990s and the 2000s. In the late 1730s the population of Ireland was about twice what it is now! In 1740 the coldest year in the Central England Temperature record occurred. This led of famine across western Europe, especially Ireland. As many people left Ireland then as did from the potato famine a century later. Probably as many died, but it is a forgotten famine because of the later on in 1845/6. The latter was due to the potato blight (and a one crop agricultural system), but the one in 1740 was purely to the weather. I'm attaching an article about this - the book to look at is by Dickson - in the references. There is something in the paper about the effects of the very cold year in different regions of Europe. The important thing in all this is the exceptional cold of the year occurred after exceptional warmth of an entire decade, so the effects were likely much worse as the population had got used to a better [warmer] climate. The conclusion of the paper is that the event was natural (with no known cause) so it could occur again! The follow on influence of this is that people are not affected much by climate or climate change. What effects them is the Weather!