New study: Global cooling led to wars, famine and plagues in 1560-1660

The Thirty Years War (1618-1648) was particularly blody 

A new study published in the PNAS (Procedings of the National Academy of Sciences of the United States of America) shows that global cooling caused wars, famine and plagues during the so called Cold Phase (1560-1660 AD),

Here is the abstract:

Results show that cooling from A.D. 1560–1660 caused successive agro-ecological, socioeconomic, and demographic catastrophes, leading to the General Crisis of the Seventeenth Century. We identified a set of causal linkages between climate change and human crisis. Using temperature data and climate-driven economic variables, we simulated the alternation of defined “golden” and “dark” ages in Europe and the Northern Hemisphere during the past millennium. Our findings indicate that climate change was the ultimate cause, and climate-driven economic downturn was the direct cause, of large-scale human crises in preindustrial Europe and the Northern Hemisphere.

The authors, as well as the article below published in Ars Technica, refer to "climate change" as the "ultimate cause" for the disasters. However, as the abstract and the article clearly indicate, the real cause for all those catastrophes was cooling. Warmer weather in the 18th century lead to a speedy recovery of both the economy and the population in Europe.

Cooling during the Cold Phase (1560-1660 AD) reduced crop yields by shortening the growing season and shrinking the cultivated land area. Although agricultural production decreased or became stagnant in a cold climate, population size still grew, leading to an increase in grain price and an increased demand on food supplies. Inflating grain prices led to hardships for many, and triggered social problems and conflicts such as rebellions, revolutions, and political reforms.
Many of these disturbances led to armed conflicts, and the number of wars increased 41 percent during the Cold Phase. During the latter portion of the Cold Phase, the number of wars decreased, but the wars lasted longer and were far more lethal—most notable was the Thirty Years War (1618-1648),where fatalities were more than 12 times of the conflicts between 1500-1619.
Famine became more frequent too. Nutrition deteriorated, and the average height of Europeans shrunk 2cm by the late 16th century. As temperatures began to rise again after 1650, so did the average height.
The economic chaos, famine, and war led people to emigrate, and Europe saw peak migration overlapping the time of peak social disturbance. This widespread migration, in conjunction with declining health caused by poor nutrition, facilitated the spread of epidemics, and the number of plagues peaked during 1550-1670, reaching the highest level during the study period. As a result of war fatalities and famine, the annual population growth rate dropped dramatically, eventually leading to population collapse.
In the 18th century, the mild climate improved matters considerably, leading to the speedy recovery of both Europe’s economy and population.

PS

This results of this study of course confirm what is wellknown from many other periods in the history of humanity: Prolonged periods of cold weather lead to a steep rise in mortality.

A more recent example from the US:

"From 1979 to 1997, extreme cold killed roughly twice as many Americans as heat waves, according to Indur Goklany of the U.S. Department of the Interior," Singer and Avery write. "Cold spells, in other words, are twice as dangerous to our health as hot weather."

Even the BBC has admitted that "Global warming 'may cut deaths."