The Long Summer

I just finished reading “The Long Summer,” a book by archaeology writer Brian Fagan about how climate change has affected the course of human history.  With my home state of California heading into a serious summer drought, a long view of the weather seemed wise.

Fagan’s “long summer” is the Holocene Period, the almost 12,000 years of relatively warm, stable climate in which human civilization began, and that continues to this day. But even a stable climate has hiccups. It’s those odd events that Fagan digs from the records of prehistory.

Three things struck me most of all. The first is how a sudden event on one side of the planet can change weather patterns far away, sometimes for an awfully long time. Take Lake Agassiz, the biggest body of water I’d never heard of. In 11,500 B.C., this vast body of glacial meltwater spanned much of the center of North America, from Manitoba to South Dakota. At some point Agassiz topped its basin and carved a channel into the St. Lawrence River. Within a few months, the lake basin spilled most of its contents into Hudson Bay. This deluge of freshwater into the Atlantic started a chain reaction that led to a thousand-year drought in Mesopotamia and wrote a death sentence for some of the Fertile Crescent’s first cities.

The second was the unpredictable consequences that even semi-regular events, like an El Nino, can have on civilizations. I was a cub reporter in California during the El Nino event of 1998, writing about hillsides that collapsed due to rain. This seemed catastrophic at the time, but it was chump change compared to the havoc that El Ninos once wreaked in ancient Egypt. As surface temperatures shift in the Pacific Ocean, the monsoon can fail over East Africa, drying up the Nile. Fagan described how between 3,000 and 1,200 B.C., El Ninos caused Egyptian grain crops to fail and empires to crumble, not once but several times.

The third is how similar our similar our situation today is to those of villagers in Mesopotamia or the Nile farmers of Egypt. Even with our digital thermometers, ice-core samples from Greenland and weather satellites, we have no idea how much rain will fall in Iowa next year. Yes, we can make a better guess, but trend reports can’t subdue the spirits of a farmer who gazes at the sky and hopes that next year will be better. We’re hard-wired to look toward a brighter future, whether that optimism is warranted or not.