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Commentary: The sun also sets

This article first appeared in the St. Louis Beacon, June 30, 2011Some people are said to be born ahead of their time. They're the visionaries who are able to see beyond the horizon of their epoch, whose ideas are often rejected by their contemporaries but ultimately transform the way we look at things.

Their uncanny prescience is a mixed blessing. On the one hand, they tend to be vindicated by history while their detractors are exposed as short-sighted, intellectual lightweights. On the other, this happy verdict is usually rendered after they're dead, leaving the prophet to gloat posthumously.

Astronomer William Herschel is today best remembered for the discovery of the planet Uranus. In 1801, however, he astonished his peers by suggesting an inverse relationship between sunspots and prices on the London wheat market. When the number of sunspots rose, wheat prices fell and when sunspot incidence fell, wheat prices rose.

This revelation was received by his peers with skepticism bordering on derision. It was generally considered to be the sort of mystical lunacy you'd expect from an astrologer, rather than a serious astronomical observer.

Unfortunately for Herschel, he made his proclamation in the midst of a solar period scientists now call the Dalton Minimum -- an extended phase of extremely low sunspot activity. The prolonged dearth of sunspots made immediate testing of Herschel's hypothesis problematic. After the sun returned to a more active state decades later, he was proved right.

Sunspot frequency fluctuates from minimum to maximum in cycles of roughly 11 years. Grain prices were found to trace a reverse pattern that lagged behind the sunspots' by a year or two. It became apparent that high numbers of sunspots precede years with longer growing seasons -- and thus larger harvests -- but nobody knew why.

An obvious explanation was that the sun in an active state must exude more energy than it did in a dormant one. However, the sun's luminosity varied by less than one-half of 1 percent throughout the cycle and this figure was thought to be insufficient to produce significant climatic impact.

Herschel's sunspot theory remained an unexplained -- and largely forgotten -- academic curiosity until the 1990s when Henrik Svensmark first proposed the notion that it is the variation in the sun's magnetic field -- not in its output of light -- that influences climate.

The Earth is constantly bombarded by cosmic radiation from deep space. Professor Svensmark, director of the Center for Sun-Climate Research at the Danish Space Institute, theorized that these high-energy subatomic particles create aerosols as they pass through our atmosphere. These aerosols, in turn, seed cloud droplets. In fact, satellite observations reflect a possible connection between cosmic ray intensity and low-level cloud formation.

According to Svensmark, an active sun produces a more robust electro-magnetic field, which repels more of this radiation while a dormant sun allows more of it to reach Earth. Increased cosmic radiation results in a corresponding increase of low-level clouds, the tops of which reflect sunlight back into space thus cooling the planet. By contrast, an active sun results in less cloud cover and a warming world.

All this could be dismissed by laymen as egghead esoterica were it not for two recent developments that lend practical significance to the matter: Svensmark demonstrated the mechanics of his theory experimentally, and the sun abruptly went to sleep.

Most research in climate science depends heavily on computer simulations of the real world. Bucking that trend, Svensmark built a cloud chamber in the basement of the Danish Space Institute. Relying solely on the naturally occurring cosmic radiation that passes through the structure, he proceeded to grow clouds underground.

This result stunned the scientific community, and he was subsequently moved to the head of the line for access to the Proton Synchrotron at the prestigious CERN nuclear institute, where an interdisciplinary team of scientists from nine different countries is studying the phenomenon.

Meanwhile, the sun is in a state of inactivity not seen since the 1600s. According to Dr. Frank Hall of the National Solar Observatory, the present solar cycle (#24) will be about one-half as strong as the previous. If the predicted trend continues, the sun's magnetic field will be too weak to produce sunspots at all during the next cycle. (Other scientists disagree.)

The last time this occurred, the planet plunged into "the Little Ice Age." The Baltic Sea routinely froze in winter and people traveled across it by sleigh between Poland and Sweden. Winter festivals were held on the Thames River and New York Harbor froze, allowing foot traffic between Manhattan and Staten Island.

There was, however, a dark side to this winter wonderland. Crop failures became commonplace and recurrent famine helped to spawn the French Revolution. The average height of males in northern Europe declined by 2.5 inches due to inadequate nutrition and the attendant spread of disease.

Of course, there are manifold factors that influence climate and Svensmark is not promoting alarmist prophecies. He does, however, predict that decreased solar activity will bring cooler, wetter summers and longer, harsher winters -- phenomena that may already be underway.

Readers who wish to monitor the sun's current nap can visit spaceweather.com for daily sunspot updates. Readers who would like to learn more about Svensmark's theory can pick up a copy of "The Chilling Stars," which he co-authored with science writer Nigel Calder. Those who merely want to know whether he's right about all of this can look out their windows, because we're about to find out.

M.W. Guzy is a retired St. Louis cop who currently works for the city Sheriff's Department. His column appears weekly in the Beacon.