Saturday, July 18, 2009

A YEAR WITHOUT A SUMMER?

1816 was the "year without a summer." There were several causes of the abnormally cold weather that year, as this source recounts:

The year 1816 is still known to scientists and historians as "eighteen hundred and froze to death" or the "year without a summer." It was the locus of a period of natural ecological destruction not soon to be forgotten. During that year, the Northern Hemisphere was slammed with the effects of at least two abnormal but natural phenomena. These events were mysterious at the time, and even today they are not well understood.
First, 1816 marked the midpoint of one of the Sun's extended periods of low magnetic activity, called the Dalton Minimum. This particular minimum lasted from about 1795 to the 1820s. It resembled the earlier Maunder Minimum (about 1645-1715) that was responsible for at least 70 years of abnormally cold weather in the Northern Hemisphere. The Maunder Minimum interval is sandwiched within an even better known cool period known as the Little Ice Age, which lasted from about the 14th through 19th centuries.

But the event that most severely shaped 1816's cold phenomena was the cata-strophic eruption the previous year of Tambora on the island of Sumbawa, in modern-day Indonesia. The ash clouds and sulfur aerosols spewed by this volcano were widespread, chilling the climate of the Northern Hemisphere by blocking sunlight with gases and particles.
If this account is correct, the "year without a summer" played a role in the development of the American Midwest:

In 1816, it snowed in June in the United States and Europe. Crops failed, there was starvation, people lost their farms, and it touched off the wave of emigration that led to the settlement of what is now the American Midwest. In the meantime, hundreds of thousands more starved around the world.
New England and Europe were hit exceptionally hard. Snowfalls and frost occurred in June, July and August and all but the hardiest grains were destroyed. Destruction of the corn crop forced farmers to slaughter their animals. Soup kitchens were opened to feed the hungry. Sea ice migrated across Atlantic shipping lanes, and alpine glaciers advanced down mountain slopes to exceptionally low elevations.

I don't think things are quite so bad this year, but if something doesn't change pretty soon 2009 may go down in history, in some parts of the U.S. at least, as another year with barely any summer. Here in Minnesota and across the Midwest, temperatures are abnormally cold. I don't know whether the phenomenon is world-wide--data that will answer this question have probably not been assembled, and may not be honestly reported--but the current low level of solar activity suggests that the cooling trend could indeed be universal.
Here in Minneapolis, the temperature never reached 70 degrees today--rather astonishing for the middle of July, our hottest month. Most days recently, it hasn't been comfortable to be outdoors in the evening without a fire and a sweatshirt. It feels more like October than July. Thankfully, and unlike 1816, it hasn't snowed; the worst consequence we fear is not getting any ripe tomatoes.

Today, walking down the street in downtown Minneapolis at 5:30, en route from my office to my parking ramp, I saw something I've never seen before: a man wearing a winter coat in July. Well, maybe not quite a winter coat, but definitely a fall/winter semi-parka with an unzipped, faux-fur lined hood. He was carrying a briefcase and looked like a businessman who was tired of being cold every time he went outdoors. In the summer.

I personally don't think that we (all of humankind, let alone we Americans) can control the weather, but for those who do think we possess that Godlike power, here's a request: can we turn the thermostat up a little?

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