Physics World
 30 Jun 2011Â
Why the recent interest in the Sun's activities?
Solar physicists agree that the Sun has been acting strangely of late. It relates to apparent abnormalities in the solar cycle, an approximately 11-year period during which the Sun's magnetic activity oscillates from low strength to high strength, then back again. When the Sun's magnetic activity is low, during a solar minimum, its surface remains relatively quiet, which leads to fewer sunspots. Then, as magnetic activity begins to increase, the surface becomes more dynamic and the sunspot numbers begin to increase in the lead up to a solar maximum.
But following the last solar minimum in 2006, solar physicists were surprised to observe that sunspot numbers were unusually slow to pick up. This led some to suggest that the next solar maximum, due in 2013, could be late and weaker than usual. Some see this as a sign that solar magnetic activity is slowing down and the Sun may be about to head into a prolonged period of magnetic weakness. Some have speculated that a weakened Sun could offset some of the effects of man-made global warming, or even counteract it entirely.
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Solar physicists agree that the Sun has been acting strangely of late. It relates to apparent abnormalities in the solar cycle, an approximately 11-year period during which the Sun's magnetic activity oscillates from low strength to high strength, then back again. When the Sun's magnetic activity is low, during a solar minimum, its surface remains relatively quiet, which leads to fewer sunspots. Then, as magnetic activity begins to increase, the surface becomes more dynamic and the sunspot numbers begin to increase in the lead up to a solar maximum.
But following the last solar minimum in 2006, solar physicists were surprised to observe that sunspot numbers were unusually slow to pick up. This led some to suggest that the next solar maximum, due in 2013, could be late and weaker than usual. Some see this as a sign that solar magnetic activity is slowing down and the Sun may be about to head into a prolonged period of magnetic weakness. Some have speculated that a weakened Sun could offset some of the effects of man-made global warming, or even counteract it entirely.
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So could we be heading for another Little Ice Age?
There are many uncertainties surrounding this question. Firstly, as explained in the previous answer, it is far from clear whether the Sun is headed for another period of calm. Recent research in the UK, predicts an 8% chance that we will return to Maunder minimum conditions over the next 40 years, based on past behaviour of the Sun over the last 9000 years.
Secondly, there are still debates over the details of the Little Ice Age and the role played by the Maunder minimum. In Europe, there were considerably more cold winters in this interval, but they were not unrelentingly cold as they were in an ice age. Also, the Earth's climate is evidently a highly complicated system, involving interconnected feedback systems, so it is difficult to disentangle causes and effects. For instance, several recent studies have suggested that solar-induced changes to the jet stream in the northern hemisphere may cause colder winters in Europe but this would be offset by milder winters in Greenland.
Finally, even if the Sun were to head into a quiet period, others argue that the reduction in solar irradiance on Earth would still be small compared with the heating caused by man-made global warming. Mike Lockwood, a researcher at the University of Reading, estimates that the change in climate radiative forcing since the Maunder minimum is about one tenth of the change caused by man-made trace greenhouse gases.
There are many uncertainties surrounding this question. Firstly, as explained in the previous answer, it is far from clear whether the Sun is headed for another period of calm. Recent research in the UK, predicts an 8% chance that we will return to Maunder minimum conditions over the next 40 years, based on past behaviour of the Sun over the last 9000 years.
Secondly, there are still debates over the details of the Little Ice Age and the role played by the Maunder minimum. In Europe, there were considerably more cold winters in this interval, but they were not unrelentingly cold as they were in an ice age. Also, the Earth's climate is evidently a highly complicated system, involving interconnected feedback systems, so it is difficult to disentangle causes and effects. For instance, several recent studies have suggested that solar-induced changes to the jet stream in the northern hemisphere may cause colder winters in Europe but this would be offset by milder winters in Greenland.
Finally, even if the Sun were to head into a quiet period, others argue that the reduction in solar irradiance on Earth would still be small compared with the heating caused by man-made global warming. Mike Lockwood, a researcher at the University of Reading, estimates that the change in climate radiative forcing since the Maunder minimum is about one tenth of the change caused by man-made trace greenhouse gases.
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Comments: 7
science writers like to jump on theories -- we do well to remember our profound ignorance
What most have not yet accepted is that suns are energy portals connected to each other and changes come with cosmic seasons (cycles) that take place over thousands of years ... IMnsHO
What sort of connection would that be, Jerry?
But let me try anyway ... everything in the UNIverse is "energetically" interconnected, there is nothing that is not. Considering GOD then, there is INtelligence INvolved and everything has a purpose of sort because everything affects everything else in some degree or other .... our sun has a relative Father Son of it's own ... too complex for me to explain now without research ... which research I would say that by far the most folks could care less about because as "far" as most folks think is only to our own sun ... (which they think of an only a physical "thing" that shares nothing but possibly gravity and "self contained" heat ... IMnsHO
Milky Way ... should keep "some" of "those" busy for a while ... the "more spiritual aspects" of my claims would probably be a waste of my writing time here.