Once again, scientific consensus proves its fallibility. NASA says that something unexpected is happening on the Sun. This year, 2013, is supposed to be the peak of the 11-year sunspot cycle—the year of Solar Max. Yet solar activity is well below the expected level. Our somnolent star refuses to behave according to the predictions of Sun watching scientists, leading some observers to wonder if forecasters missed the mark. The botched solar forecast not only has implication for our understanding of the physical processes inside the Sun, it has possible links to future climate change here on Earth. Scientists admit that no one knows for sure what the Sun will do next.
The 11 year solar cycle—the waxing and waning of activity on the Sun—is well known, if not well understood. The solar cycle is the periodic change in the Sun’s activity, including changes in levels of solar radiation and the ejection of solar material. Solar cycles have been observed for hundreds of years by earthbound observers noting changes in the sun’s appearance. Generations of scientists have kept detailed records of changes in the number of sunspots, flares, and other visible manifestations. Changes in solar activity affects space weather, which can be important when launching satellites. It can also impact conditions here on Earth, adversely affecting communications, radio broadcasts and power grids. For these reasons, forecasting the solar cycle is not just an idle pursuit for Sun gazing scientists.
A number of techniques are used to predict the timing and amplitude of a cycle, often involving observations made just prior to a sunspot minimum. Relationships have been found between the size of the next cycle maximum and the length of the previous cycle, the level of activity at sunspot minimum, and the magnitude of the previous cycle. Among the most reliable prediction techniques use observed changes in Earth’s magnetic field, taken during and before a sunspot minimum. Solar storms cause changes in the Earth’s magnetic field but the precise connections between them and future solar activity levels remains uncertain. Using these techniques and others, a panel of solar experts made a prediction about the expected peak for Solar Cycle 24.
May 8, 2009 — The Solar Cycle 24 Prediction Panel has reached a consensus decision on the prediction of the next solar cycle (Cycle 24). First, the panel has agreed that solar minimum occurred in December, 2008. This still qualifies as a prediction since the smoothed sunspot number is only valid through September, 2008. The panel has decided that the next solar cycle will be below average in intensity, with a maximum sunspot number of 90. Given the predicted date of solar minimum and the predicted maximum intensity, solar maximum is now expected to occur in May, 2013. Note, this is a consensus opinion, not a unanimous decision. A supermajority of the panel did agree to this prediction.
Once again, scientific consensus proves its fallibility. We are currently over four years into Cycle 24. The current predicted and observed size makes this the smallest sunspot cycle since Cycle 14 which had a maximum of 64.2 in February of 1906. Even so, the weak early peak and subsequent trailing off of activity has solar scientists scrambling to revise their forecasts. Activity to date is shown in the plot below.
The early peak and shortfall in activity can easily be seen in the sunspot record shown in the plot. The panel’s prediction of a May 2013 peak was made during the deepest minimum in nearly a hundred years, with sunspot numbers near zero and x-ray flare activity flat-lined for months at a time. Recognizing that deep minima are often followed by weak maxima, a wimpy maximum was expected, but not quite this wimpy. Given the lack of solar activity in February 2013, a maximum in May now seems unlikely.
Solar physicist Dean Pesnell of the Goddard Space Flight Center notes that the Sun has been acting a bit contrary in recent cycles. “The last two solar maxima, around 1989 and 2001, had not one but two peaks,” he reports on a NASA website. Solar activity went up, dipped, then resumed, performing a mini-cycle that lasted about two years. Indeed, sunspot counts jumped in 2011, dipped in 2012, and Pesnell is now betting that the same thing could be happening again.
“This is solar maximum,” he says. “But it looks different from what we expected because it is double peaked. I am comfortable in saying that another peak will happen in 2013 and possibly last into 2014.”
On longer than decadal time scales, the Sun has shown considerable variability, that variability often correlating with century long trends in Earth’s climate. These periods include the long Maunder Minimum, when almost no sunspots were observed, the less severe Dalton Minimum, and the increased sunspot activity during the last fifty years known as the Modern Maximum. The causes for these variations are not well understood, but because sunspots affect the brightness of the sun, solar luminosity is lower during periods of low sunspot activity. It is widely believed that the lack of solar activity during the Maunder Minimum and earlier periods may be among the principal causes of the Little Ice Age.
The Modern Maximum is between 1900 and 1950, and levels have remained fairly high until recent years. Given that climate cannot change instantaneously with changes in solar output—temperature change has a time lagged correlation—the link between solar activity and the modest global temperature increase during the 20thcentury seems obvious. Given that the Sun powers practically all life on Earth and drives the planetary climate engine the question has to be asked, why did the IPCC climate change alarmists try to attribute the increase to CO2?
Granted, four centuries is not a long time in the grand sweep of things and reliable sunspot observations are not available for ancient times. Fortunately, taking a page from other historical climate studies, there are proxy data that can extend our view into the past correlation of solar activity and climate change. That proxy is 14C, carbon-14. This is the same isotope of carbon that makes dating organic substances possible. This is because 14C is created by sunshine and has a relativity short half-life ( years). The concentration of 14C present in the atmosphere depends on the intensity of solar irradiance, so historical concentrations are an indicator of solar activity. A plot of historical levels for the past 1100 years are shown below.
Again, the fluctuation in solar activity correlates well with known historical periods of both warm and cold climate conditions.