Pure history, 1570 through 1680, mostly of Europe, though Blom touches on the rest of the world from time to time. Why Europe? Because the records are the most extensive. Why those dates? Because they are the coldest (with some exceptional outliers before and after) period of the “Little Ice Age,” and it is that period, and the social, cultural, economic, and political changes that occurred during that century, largely compelled by the cold, that this book is about.

Earth scientists call the five centuries between 1300 to 1800 C.E. the “Little Ice Age.” At the beginning of this period, the Earth began to cool, reaching its lowest temperature, 2C below the 1300 average around 1570, and remaining there until 1680 or so when it began slowly to warm back to pre-1300 levels reaching them in the mid-1850s—Note that this is fifty years after the beginning of the industrial revolution. There have been other coolings in the not-to-distant past. The Earth’s northern hemisphere became unusually cold from 535 to around 545 C.E., but this shorter (10-year) cooling can be traced directly to large Icelandic volcanic eruptions. No one quite knows what factors contributed to the much longer cool period beginning in 1300. 

So what happened? Well, for one thing, the weather changed. More storms, more droughts, much colder summers. Crops could not grow properly in foreshortened growing seasons; fruits would not ripen. In short, people starved. The result, over the first two generations of the coldest period, was a revolution in economics, trade, and agriculture that saw small subsistence farming converted into much larger, more efficient farming that provided for storage of excess product in good years (there were some) and trade in the bad ones. Such changes proceeded at different rates in different parts of Europe. Some of this difference was driven by political and religious ideology (Spain and Italy were more conservative than England or Scandinavia) and partly by climate. Spain was colder than usual but not as cold as Denmark.

There was also a revolution in thinking supported by the availability of books, thanks to Guttenberg. The foundations of “The Enlightenment” were laid in this period. Blom spends much of the book describing the thinking and the thinkers of this period and, in particular, their new-found ability to move around the continent, relocating to places where their thinking was better appreciated. This was the beginning of modern science and political philosophy. Blom asserts that all of these changes were more or less directly (economics and politics) or indirectly (philosophy, nascent science) tied to the cold. 

Ending the book, Blom asks what the Little Ice Age can teach us about our present issues with climate change. Alas, there isn’t much it can teach us except that we should prepare for a long bout with geophysical changes (and their effects like reduction in food production, pandemics, and wars) that will surely cause a complete rearrangement of global civilization, including the likely (Blom doesn’t say this but read between the lines) collapse of the present world order. The Thirty Years War (1618-1648) was right in the middle of the cold.

Alas, our situation is very different, something Blom mentions but does not elaborate. In the Little Ice Age, sea levels dropped a bit, something easier to deal with than our present situation. Moreover, our present situation is a result of our activity. There were not enough humans on Earth to have greatly impacted the global climate. Lastly, in the past, the climate changed and then changed back. It isn’t going to change back this time. Even should humans, or at least their industrial activity, be extinguished, and the population shrinks to where it was in 1600 or earlier, the climate will not “change back” for possibly thousands, even tens of thousands, of years. See my review of The Uninhabitable Earth.