That old Climate may be pretty nimble...

kw: book reviews, climatology, history, anthropology

One of my brothers, a Mayan archaeologist, was interviewed for the Discovery Channel a couple years ago. He told of the destruction of the forest around Palenque because the Mayans used huge quantities of charcoal to make stucco. All their buildings are plastered with several inches of stucco, perhaps as insulation.

Among more than a hundred theories about the destruction of the Mayan civilization some 1100 years ago, regional drying and crop failures are a prominent part of many. Regional or global climate shifts have been proposed only recently.

Among the many factors one may list, we must take account of a major dry period in all of Mesoamerica from about 750 AD to about 950 AD. Civilizations are defined by their mass effort to mitigate the effects of bad periods. They stave off droughts and other disasters, even ones that may last a few years, as the U.S. survived—though with much suffering—the dust bowl years of the 1930s, and as Joseph's Egypt was able to survive a 7-year famine around 1900 BC (with divine forewarning).

No civilization has survived a 200-year drought, though the Mayans came close: the Mayan collapse occurred in three phases beginning in 760 (about ten years into the drought) and ending about 910. Had they hung in there for another generation or two, they'd be a major civilization today.

The details needed to pin down such stories are found in abundance in The Winds of Change: Climate, Weather, and the Destruction of Civilizations by Eugene Linden. Note carefully, the word "Civilizations". This book does not forecast "the destruction of civilization", but reports on the destruction of a number of civilizations in the past, and points out the environmental and climatological influences that coincide with them. While one coincidence does not imply causality, many coincidences of the same type make a strong case.

Author Linden presents his material as a case, with opening arguments, presentation of evidence, cross-examination and rebuttal, and closing arguments. This format leads to some rather dry reading. Fortunately, much of the book is well and stirringly written, and he makes a good case.

It is a puzzle that, as an increasing majority of scientists agree that climate can change rapidly and violently, has done so in the past, and appears to be on the verge of doing so in our lifetimes, public and media complacency—even denial—are at an all-time high. To most people, "long term planning" means at most five years. Most retirement advisers work with a horizon of thirty to forty years. Futurists, even my favorite, Bruce Sterling, write about the next fifty years with great frequency, scarcely about longer periods. Few folks can think in terms of something global in scope and multi-generation in effect. We need stories with more immediacy.

So, I really like these articles about poison ivy: Global warming may aid poison ivy and CBC News: Poison ivy itchier when carbon dioxide levels increase. Even if we freeze CO₂ production at current levels, the atmospheric content will rise from the current level of about 370 ppm (0.037%) to 570 ppm (0.057%) by 2050. At that level, poison ivy in an experimental forest with extra CO₂ gas in the air was found to grow 150% faster each year, compared to plants grown without the extra CO₂, and they contained 150% more urushiol, of a more toxic variety.

Let's work this out: 150% faster means for each pound of poison ivy in Forest A, Forest B produces 2.5 pounds; 150% more urushiol means each pound of leaves contains 2.5 times as much of the stuff. Put it together, and Forest B has 2.5x2.5 = 6.25 times as much urushiol production per acre! And the icing on the cake? Urushiol is a mix of oils of varying toxicity. Forest B urushiol has a larger proportion of the worst oils.

In Japan, this might be considered a good thing, because they use urushiol to make the lacquer for lacquerware (the lacquer isn't toxic), and to paint all those lovely temples and palaces. For the rest of us, forest burning anywhere will create six times as much toxic smoke. My wife has caught bad rashes from dried leaf bits blowing around. More CO₂ means an itchier future. That hits home with me more than an extra meter of ocean water.

"The Winds of Change" sounds an alert. The author is not being alarmist. He is frustrated at our case of galloping apathy. Perhaps, to paraphrase Ronald Reagan, to keep a car that is getting bogged down off one side of the road from falling further, it is necessary to plant oneself firmly on the other side with a tow truck, and pull HARD.

It is now known to everyone who cares to look, that past climate changes have been abrupt and violent. The "Little Ice Age" of the 14^th-18^th Centuries was less violent than most, yet it caused widespread misery, appalling death rates, indirectly fostered staggering epidemics, and changed Western society permanently...another century and the Renaissance would have died aborning. Dare we neglect signs that the climate is about to make a major switch?