Sunspots are huge magnetic storms on the sun that can be thousands of miles in diameter. They appear as dark spots because their temperature is slightly cooler than the surrounding surface. They are present when the sun goes through the “active” phase of its approximately 11-year cycle. Currently, the sun is generating tremendous solar storms, an indication of increased intensity of its magnetic field.
Typically, the sun goes from no storms at all to a ferocious period of activity every 11 years. Scientists do not have a clear explanation for why this variability occurs, but likely it is a result of fluctuating convection currents within the sun. Outbursts of superheated plasma from solar storms can cause problems on Earth if the Earth happens to be in the line of fire, interfering with the electronics of satellites and communications. But the sun’s strong magnetic field, of which sunspots are a byproduct, is a vital necessity for protecting life on Earth from cosmic radiation.
In effect, the sun’s magnetic field creates a shield that greatly reduces the amount of harmful radiation reaching the Earth from outer space. But it also, in an indirect way, helps maintain a stable climate, at least according to a recent hypothesis.
The period from about 1650 to 1710 is known at the “Little Ice Age.” Not every year during that period was colder than average, but overall the temperature dropped an average of about two degrees Fahrenheit in the Northern Hemisphere. Two degrees doesn’t sound like much, but it led to crop failures, food shortages and social unrest, particularly in Europe. The Thames River, which flows through London, England, froze over during winter months. Scientists have speculated on reasons why this period of cooling occurred. Some suggested reasons include increased volcanic activity, shifting ocean currents, as well as a dip in the amount of light and heat the sun produced.
Modern measurements, however, have shown that the sun’s light and heat output remain nearly constant with little difference, even during times of increased solar storms. And yet observations by science-minded people of the time indicate that during the Little Ice Age, sunspot activity was almost completely absent. Researchers have wondered if it was mere coincidence that the reduced sunspot activity coincided with a noticeable drop in average temperatures, but if there was a connection, it had eluded them.
Now, a few scientists believe they have found that connection. Their reasoning goes like this: During a protracted solar minimum, which occurred during the Little Ice Age, the sun’s magnetic field becomes weaker (as evidenced by reduced sunspot activity). This allows more cosmic rays to penetrate Earth’s atmosphere. The cosmic rays interact with molecules and atoms in the atmosphere creating microscopic grains of “dust.” These particles attract water vapor, creating tiny droplets of water, which enhances the development of clouds. (Every raindrop forms around a microscopic particle. Without such airborne particulates, there would be no rain.) Increased cloud cover blocks a corresponding amount of solar radiation, thereby decreasing the temperature. This is the scenario now being proposed as the reason for the Little Ice Age.
Further research is required to verify this hypothesis. But it does explain the “coincidence” of a period of virtually no sunspot activity and a period of cooling in the Northern Hemisphere.
The other point of note is the degree to which Earth’s climate changed with just a two-degree reduction in temperature. Presently, average temperatures are rising worldwide, and the consequences are already evident.
Email Terry Mejdrich at email@example.com.