That’s one possible conclusion, and one a group of Russian scientists see from the changing behavior of the sun, and sunspots in particular.
Ray of hope: Can the sun save us from global warming?
Could the Sun's inactivity save us from global warming? David Whitehouse explains why solar disempower may be the key to combating climate change
Published: 05 December 2007
Something is happening to our Sun. It has to do with sunspots, or rather the activity cycle their coming and going signifies. After a period of exceptionally high activity in the 20th century, our Sun has suddenly gone exceptionally quiet. Months have passed with no spots visible on its disc. We are at the end of one cycle of activity and astronomers are waiting for the sunspots to return and mark the start of the next, the so-called cycle 24. They have been waiting for a while now with no sign it's on its way any time soon.
Sunspots – dark magnetic blotches on the Sun's surface – come and go in a roughly 11-year cycle of activity first noticed in 1843. It's related to the motion of super-hot, electrically charged gas inside the Sun – a kind of internal conveyor belt where vast sub-surface rivers of gas take 40 years to circulate from the equator to the poles and back. Somehow, in a way not very well understood, this circulation produces the sunspot cycle in which every 11 years there is a sunspot maximum followed by a minimum. But recently the Sun's internal circulation has been failing. In May 2006 this conveyor belt had slowed to a crawl – a record low. Nasa scientist David Hathaway said: "It's off the bottom of the charts... this has important repercussions for future solar activity." What's more, it's not the only indicator that the Sun is up to something.
Sunspots can be long or short, weak or strong and sometimes they can go away altogether. Following the discovery of the cycle, astronomers looked back through previous observations and were able to see it clearly until they reached the 17th century, when it seemed to disappear. It turned out to be a real absence, not one caused by a lack of observations. Astronomers called it the "Maunder Minimum." It was an astonishing discovery: our Sun can change. Between 1645 and 1715 sunspots were rare. About 50 were observed; there should have been 50,000.
Ever since the sunspot cycle was discovered, researchers have looked for its rhythm superimposed on the Earth's climate. In some cases it's there but usually at low levels. But there was something strange about the time when the sunspots disappeared that left scientists to ponder if the sun's unusual behaviour could have something to do with the fact that the 17th century was also a time when the Earth's northern hemisphere chilled with devastating consequences.
Scientists call that event the "Little Ice Age" and it affected Europe at just the wrong time. In response to the more benign climate of the earlier Medieval Warm Period, Europe's population may have doubled. But in the mid-17th century demographic growth stopped and in some areas fell, in part due to the reduced crop yields caused by climate change. Bread prices doubled and then quintupled and hunger weakened the population. The Italian historian Majolino Bisaccioni suggested that the wave of bad weather and revolutions might be due to the influence of the stars. But the Jesuit astronomer Giovanni Battista Riccioli speculated that fluctuations in the number of sunspots might be to blame, for he had noticed they were absent.
