Monday, January 21, 2008

It's Always the End of the World As We Know It: A Review of The Little Ice Age

Today is the last day of the winter term break at UNM, and tomorrow I begin the spring term studies. My time to read what I want will become more limited as my spring semester studies begin in earnest by the end of this week. So over the weekend just past, I completed a book I had begun shortly after the secular new year.

Tomorrow is also Tu B'Shevat, the Jewish New Year of Trees, which is the Jewish Arbor Day, and has become a time to consider our dependence on Earth's ecology. It is therefore doubly fitting that I finished reading Brian Fagan's The Little Ice Age: How Climate Made History 1300-1850. (Basic Books, New York, 2000) just this morning.

In honor of Tu B'Shevat, then, as well as a commemoration of 5 weeks in which I got a lot of miscellaneous reading done, I thought I'd discuss this book today on my blog.

I first heard about a climatic event called 'the little ice age' when I was working on a BS in Geology in Illinois in the early '80's. It was discussed briefly in the Historical Geology course I was taking, as well as later, in an Astronomy class that I took for fun. I knew it as a period of colder climate that affected primarily the northern hemisphere during the early modern period, that it was preceded by the Medieval Warm Period and followed by the Modern Warm Period, in which the earth's average temperature once again is stable, high and climbing. There was some speculation at the time that changes in ocean currents in the north Atlantic Ocean may have been a cause of the colder period that followed the Medieval Warm Period. Later, when I was studying Paleoclimatology under Dr. Roger Andersen at UNM, I heard more about how changes in water salinity in the north Atlantic could have stopped the warm Gulf Stream from crossing east south of Greenland, thus affecting the climate of Europe during the little ice age. So when I saw Fagan's book toward the bottom of the stack on weather at our little East Mountain Branch library, I thought I might find out more about this interesting period in European and Earth history.

I read the preface at the library, while waiting for N. to finish his selections. I tend to do this in order to decide which books that I have taken off the shelves are really worth checking out and lugging home. What really intrigued me was that Fagan promised the reader that he would not only discuss the little ice age in terms of the science we have now, but also the impact it likely had on European history, as well as how ongoing climate change might continue to affect us. Fagan wrote:

"Humanity has been at the mercy of climate change for its entire existence. Infinitely ingenious, we have lived through at least eight, perhaps nine, glacial episodes in the past 730,000 years. Our ancestors adapted to the universal but irregular global warming since the end of the Ice Age with dazzling opportunism. They developed strategies for surviving harsh drought cycles, decades of heavy rainfall or unaccustomed cold...(but t)he price of sudden climate change in famine, disease and suffering, was often high." (Preface p. xii).

Fagan then discussed the current state of the science of reconstructing the climatic fluctuations and what that means for what we know, saying: "...the Little Ice Age was far from a deep freeze. Think instead of an irregular see-saw of rapid climatic shifts, driven by complex and still little-understood interactions between the atmosphere and the ocean...the Little Ice Age was an endless zigzag of climatic shifts, few lasting more than a quarter century. Today's prolonged warming is an anomaly." (Preface, p. xiii).

I was hooked! This was going to be really interesting, especially given all of the controversy about global climate change in our discussion of the politics of the day. So often, as I have discussed here, we tend to think of the past climate as if it was one long now, with change only happening in the future, and we think in very short periods of time.

Fagan structured the book in four parts, each about a particular time period related to the subject, and each part is divided into chapters that discuss the the climatic shifts, the science behind their causes as we know them, and the related historical events and social changes that were affected, at least in part, by the climate. Part I, Warmth and Its Aftermath, gives information about the Medieval Warm Period and the social and agricultural activities that it affected, such as the Norse exploration of Iceland, Greenland, and North America (Vinland), and the increasing agricultural use of lands northwards and at high elevations in Europe. He then discusses the North Atlantic Oscillation (the NAO, similar to the ENSO cycle of the Pacific) and how the stability of the NAO contributed to the warm period and how the predictability of the climate encouraged the medieval European social structure called "the Full World" by the French. He then discusses how, by the end of the Medieval Warm Period, the NAO was weaker and more unpredictable, leading to the Great Famine of 1315 - 1321 signaled the beginning of the instability of the Little Ice Age.

Part II, The Cooling Begins, starts with a discussion of the 'climatic see-saw' that characterized the Little Ice Age. Here Fagan outlines the evidence for changes in climate found in tree rings and ice cores, and ties this information to events such as volcanic eruptions, and descriptions of storms and bad weather. He then outlines how these climatic changes first affected trade in the North Sea and with Iceland and Greenland, the breaking of the Hanseatic League monopoly on cod fisheries, and the abandonment of the Greenland Western Colonies. He also discusses the development of ships better able to withstand storms and ice, as well as the economics behind these changes and how they were precipitated, in part, by the climate see-saw.

In Part III, the End of the 'Full World,' Fagan turns to the organization of European agriculture at the end of the Medieval Warm Period, and the changes brought on by the onset of an unpredictable climate. He begins this part with a description of subsistence agriculture and what it means: farmers grow enough to feed a small number of people for that year, and they may harvest enough to survive one bad year, but no more. Fagan then goes on to explain how the rapid climatic shifts and many bad years during the Little Ice Age resulted in an agricultural revolution in Europe, but not all at once and not for everyone. Political structures and custom, as well as the varying impact of the unpredictable NAO on different regions, had much to do with which parts of Europe developed more intensive commercial agriculture and when. The Low Countries and England, both politically more innovative, did so first, and France, with its entrenched nobility and top-down decision making was dead last. The Little Ice Age, Fagan says, did not in itself cause the violence of the French Revolution, but climatic shifts resulting in a series of bad harvests had a hand in the timing of it. To me this part was the most compelling in the book, because in it, Fagan related events to a much more precise understanding of the climate at the time, for in discussions of more recent events, records using modern measurements of temperature and precipitation were available. This part ends with descriptions of two catastrophic events that came near the end of the Little Ice Age: the Year without a Summer brought on by the eruption of Tambora, and the 'Great Hunger' of the Irish Potato Famine, brought on by a combination of climate, oppressive political rule and indifference of the English, and the establishment of monocultural subsistence farming in Ireland.

Fagan concludes the book in Part IV, The Modern Warm Period, with a discussion of what we do and do not know about the causes of the current global warming. Currently, he says, the data show that we are experiencing warming equivalent to the Medieval Warm period, and thus can expect to see vineyards in Britain, and the movement of arable land northward and to high elevations. But is this the result of the cycle of warming and cooling that the earth has experienced since the end of the last glacial period, or does human activity (increasing greenhouse effect due to the burning of hydrocarbons) play a major role now? The answer, Fagan says, will not be definitively know for possibly 30 more years, although the evidence points to an increased role for human activity. This is because we are only now beginning to understand the role of solar activity (sunspot cycles--minimums and maximums, as well as changes in solar radiation) in producing earth's climatic cycles. (You can find more about this topic here). I found this little discussion compelling, and I want to share it with you:

"What form will this (new era of climate change) take? One school of thought...is serenely unfazed by global warming. Gradual climate change will bring more benign temperatures...milder winters and more predictable weather--much like earth in the time of the dinosaurs. Humanity will adjust effortlessly to its new circumstances, just as it has adjusted to more extreme changes in ancient times.

"The record of history shows that this is an illusion. Climate change is almost always abrupt, shifting rapidly within decades, even years, and entirely capricious. The Little Ice Age was remarkable for its rapid changes...(and) the same pattern of sudden change extends back to the Great Ice Age of 15,000 years ago, and probably to the very beginnings of geolocical time." (p. 213).

The very last paragraphs of the book describe how glacial melt-water flowing into the North Atlantic 11,000 years ago completely shut down the warm oceanic conveyor currents, and stopped an earlier warming period "in its tracks." This created the Younger Dryas, a 1,000 year long cold period that brought Europe to near-glacial conditions. It happened rapidly, within a decade or two, and was a complete climatic shift.

Fagan says: "Even if the present warming is entirely of natural origin...we and our descendents are navigating uncharted climatic waters. In that respect we are no different than medieval farmers or eighteenth-century peasants, who took the weather as it came. Today we can forcast the weather and model climatic change, but globally we are still as vulnerable to climate as were those who endured the famine of 1315 or the storms of the Spanish Armada...The vicissitudes of the Little Ice Age remind us of our vulnerability again and again..." (p. 217).

It will take me some time to really chew over the lessons of the Little Ice Age, its impact on history, its warnings for the future. But I can say now that one thing that made this book so fascinating and so compelling to my thought, was that Fagan did not, in the end, attempt to give a definitive answer about global climate change and its trajectory and causes. Nor was he overly prescriptive in what we ought to do, if anything, to meet its challenges. Rather, he shows us through eyewitness descriptions, science, literature and art, how suddenly, how irrevocably the world as we know it can change, and has changed. Indeed, when we face an unknown future, it's always "the end of the world as we know it."

8 comments:

Kaber said...

very interesting! Ki (11) is always talking about Global Warming and how it's hurting certain animals. I tried to tell him that the world has always have climate changes that change the way of life on earth. But I really don't now much about that. Maybe it's a book I should look into reading.

Thanks for the comment. MILK with heat anc choclate is the best way to have it!

Melora said...

Sounds like a neat book, and I enjoyed your synopsis!

~L~ said...

I am so getting this book. I am fascinated by The Little Ice Age, but I have only seen it discussed in documentaries up to now.

Kaber, the current climate changes aren't restricted to Global Warming, per se, but what makes them different from the rise and fall of the past millenia is that they aren't going back down. The CO2 levels continue to rise, unchecked by the natural rhythms. What historical records like this one do for us is give us a glimpse of how subtle changes in temperature can have drastic effects. That's what is so concerning.

Elisheva Hannah Levin said...

Kaber: In earth's history, climate change is often accompanied by changes in the ranges of the flora and fauna on earth. There can be rapid speciation as well as the loss of species unable to adapt. If Ki is interested in extinction, there are some really good books out now about the major extinction events, such as the Permian and K-T extinction events. If he is more interested in how species adapt and how ranges change, then I recommend E. O. Wilson's The Diversity of Life.

Melora, thanks! I truly enjoyed the book.

~L~: Thanks for stopping by! Yes, the CO2 levels do continue to rise, and we are not certain what that will do to the underlying rhythm of warming and cooling that seems to result from solar cycles, and interactions between the atmosphere and the oceans. It could precipitate a faster cooling--as more water in the atmosphere falls as snow at the poles--thus maintaining the glacial cycles but with a different rhythm. It could also change the climatic regime altogether. Currently the warming is not much different, temperature-wise from the Medieval Warm Period. But that lasted 300 years. It's a cool time to be interested in climate, that's certain.

Amie said...

Sounds like an interesting level-headed book. The book mentions it's an illusion that climate change occurs gradually but rather it changes abruptly. I've heard people state the opposite asx proof that the recent rapid change in climate is caused by man.

Rational Jenn said...

That sounds like an interesting book! Does it presuppose a certain level of scientific knowledge or could someone (like me!) with just some basic knowledge and brains understand it?

Elisheva Hannah Levin said...

Amie--yes, I have heard that, too. For reasons I outlined in this review, and also in my other post about global climate change, I think it is more accurate to say that we don't know the extent to which humanity has contributed to the current warming. At the moment, it looks much like the medieval warming period, which was definitely not caused by the human use of hydrocarbons.

Rational Jen--this book is written for an intelligent, popular audience. It is not a textbook. Believe me, I am a scientist, but I would not read a textbook for pleasure.

Debby said...

This book sounds great! I've added it to my list and put it near the top.

I've read about the Little Ice Age as part of my history classes due to their effects on Northern European countries. It should be very interesting to read a book that combines the history with the science.