Quiet Sun, Deadly Sun

  • Date: 28/06/11

Much fanfare was associated with the reappearance of sunspots earlier this year, marking the beginning of a new period of high solar activity. Now come a number of reports saying the Sun is most likely headed for a prolonged period of low activity, possibly rivaling the Maunder minimum. Three independent studies of the Sun’s dynamics all predict that the next solar cycle will be significantly delayed and might even be skipped. The Maunder minimum is associated with a prolonged period of climate cooling known as the Little Ice Age. Whether Earth’s climate is headed for a significant cooling trend has become a matter of heated debate, while at the same time NASA is warning that a quite Sun can also be a deadly Sun. In the 1850s, following a period of low sunspot activity, the largest coronal ejection event ever witnessed caused havoc with telegraphs and ship’s compasses around the world. Such an ejection today could cause widespread power outages and failure of electronic equipment. Will our star turn both quiet and deadly?

Sunspots are relatively cool, dark blemishes on the Sun’s surface that indicate regions of intense magnetic activity. Some sunspots are gigantic, often wider than Earth with magnetic fields reaching far into space. For centuries scientists have been using sunspots to gauge solar activity, discovering that visible activity waxes and wains in a regular 11 year cycle. After an unusually quiet period we are now in Solar Cycle 24, which should peak sometime in 2013. But it is what solar scientists are predicting to come after SC 24 that is causing concern among climate scientists.

Sunspot with Earth shown to scale.

Newly reported solar observations, including fading sunspots and weakening magnetic activity near the poles, could be indications that the Sun could be less active in the coming years. Three independent studies by solar experts all predict that the next solar cycle may not happen, or at least be significantly delayed. Astrogeophysicist Frank Hill and colleagues at the National Solar Observatory, have been monitoring solar cycles using a technique called helioseismology. Hill was the lead author on the first of three papers on these results presented at the American Astronomical Society conference in New Mexico. Using data from the Global Oscillation Network Group (GONG) of six observing stations around the world, the team translates surface pulsations caused by sound reverberating through the Sun into models of its internal structure.

Hill et al have been tracking buried “jet streams,” an east-west zonal wind flow encircling the sun called torsional oscillation. Bands of flowing material originate near the Sun’s poles and migrate toward the equator. These bands are thought to play a role in generating the Sun’s magnetic field and the latitude of this wind stream matches the new spot formation in each cycle. It successfully predicted the late onset of the current Cycle 24. “We expected to see the start of the zonal flow for Cycle 25 by now,” Hill explained, “but we see no sign of it. This indicates that the start of Cycle 25 may be delayed to 2021 or 2022, or may not happen at all.”

The trend includes sunspots from Solar Cycles 22, 23, and 24.

In the second paper, Matt Penn and William Livingston report a long-term weakening trend in the strength of sunspots. Spots are formed when intense magnetic flux tubes erupt from the interior and keep cooled gas from circulating back to the interior. For typical sunspots this magnetism has a strength of 2,500 to 3,500 gauss, with a minimum field of at least 1,500 gauss to form a dark spot. Penn and Livingston predict that by Cycle 25 magnetic fields erupting on the Sun will be so weak that few if any sunspots will be formed. According to the press release:

Using more than 13 years of sunspot data collected at the McMath-Pierce Telescope at Kitt Peak in Arizona, Penn and Livingston observed that the average field strength declined about 50 gauss per year during Cycle 23 and now in Cycle 24. They also observed that spot temperatures have risen exactly as expected for such changes in the magnetic field. If the trend continues, the field strength will drop below the 1,500 gauss threshold and spots will largely disappear as the magnetic field is no longer strong enough to overcome convective forces on the solar surface.

Finally, In the third report, Richard Altrock, manager of the Air Force’s coronal research program at NSO’s Sunspot, NM, facilities has observed a slowing of the rapid poleward shift of magnetic activity observed in the Sun’s corona. Sun watchers call this shift the “rush to the poles,” a well-known pattern where new solar activity emerges first at about 70 degrees latitude at the start of a cycle, then moves toward the equator as the cycle ages. At the same time, the new magnetic fields push remnants of the older cycle as far as 85 degrees poleward.

“In cycles 21 through 23, solar maximum occurred when this rush appeared at an average latitude of 76 degrees,” Altrock said. “Cycle 24 started out late and slow and may not be strong enough to create a rush to the poles, indicating we’ll see a very weak solar maximum in 2013, if at all. If the rush to the poles fails to complete, this creates a tremendous dilemma for the theorists, as it would mean that Cycle 23’s magnetic field will not completely disappear from the polar regions (the rush to the poles accomplishes this feat). No one knows what the Sun will do in that case.”

“A key thing to understand is that those wonderful, delicate coronal features are actually powerful, robust magnetic structures rooted in the interior of the Sun,” Altrock explained. “Changes we see in the corona reflect changes deep inside the Sun.” Altrock based his work on four decades of observations with NSO’s 40-cm (16-inch) coronagraphic telescope at Sunspot.

Averaged yearly sunspot numbers. Source NASA.

The bottom line on all of this is that many experts are now predicting a big drop in solar activity in the future. And while some climate change alarmists are dismissing the possible impact of a newly somnolent Sun, others say this could lead to a new Little Ice Age. “If we are right, this could be the last solar maximum we’ll see for a few decades,” Hill said. “That would affect everything from space exploration to Earth’s climate.”

Recent research has, indeed, linked a quiet Sun to colder climate, yet the advocates of anthropogenic global warming insist the Sun doesn’t matter, that human CO2 emissions will overpower the changes in our local star. Consider this mild statement from sciencenews.org:

During the last extended period of solar dormancy, from 1645 to 1715, Europe plunged into some of the coldest winters on record. But Earth’s atmosphere, which now contains an abundance of greenhouse gases, differs in composition compared with three centuries ago, and solar physicists say they’re unsure how a long solar hiatus would affect the planet’s 21st century climate.

Others have not been so measured in their response, even to the point of impugning the reputations of some of the scientists involved. Regardless, the prospect of imminent global cooling certainly throws a wrench into the climate alarmists tale of woe and bolsters the case for a wait and see attitude.

Meanwhile, officials in Britain and the United States are preparing to make controlled power cuts to their national electricity supplies in response to a warning of a possible powerful solar storm hitting the Earth. In an interview withThe Independent, Thomas Bogdan, director of the US Space Weather Prediction Center, said that controlled power outages will protect the National Electricity Grids against damage. Without the preemptive measures severe damage could result, which could take months or years to repair. As a recent article on the NASA Science News website put it:

As 2011 unfolds, the sun is once again on the eve of a below-average solar cycle—at least that’s what forecasters are saying. The “Carrington event” of 1859 (named after astronomer Richard Carrington, who witnessed the instigating flare) reminds us that strong storms can occur even when the underlying cycle is nominally weak.

How bad was the Carrington event? Normally, solar storms do not affect people on Earth’s surface. Radio communications may be disrupted and dramatic aurora displays may paint the night skies with ghostly dancing light, but generally there is no threat to those living on the planet’s surface. In space, on the other hand, large solar explosions can potentially damage satellites and other spacecraft. Of course, as with everything in nature, there are exceptions.

A repeat of the Carrington event would be worse today.

On the morning of Thursday, September 1, 1859, English solar astronomer Richard Carrington noted the appearance of an enormous group of extraordinarily bright spots on the face of the Sun. Before dawn the next day, skies all over Earth erupted in brilliant auroras so intense that newspapers could be read as though it were daylight. Miners on Colorado stumbled out of bed and started preparing breakfast, thinking the Sun already up. Stunning auroras appeared even in tropical latitudes, painting the skies over Hawaii and the Bahamas blood red.

More troubling, ships’ compasses no longer functioned properly, birds temporarily lost their ability to navigate and telegraph systems around the world were knocked out. Sparks from telegraph keys shocked their operators and set telegraph paper on fire. The Carrington Event’s massive coronal mass ejection was sent directly toward Earth, taking only 18 hours to travel the 150 million kilometer distance. Quite remarkable, since such journeys normally take three to four days.

The solar eruption was monstrous, measuring more than X30 on the Solar Richter scale. Though the two scales cannot be directly compared, if the equivalent of the solar explosion were transferred to Earth it would register more than 17 on the terrestrial Richter scale. The total energy emitted was equivalent to tens of millions of atomic bombs exploding at the same time.

Now NASA is warning that it could happen again, and today the situation would be much more serious. Cascading blackouts carried across continents by long-distance power lines could last for weeks to months as engineers struggle to repair damaged transformers. GPS navigation units would no longer function reliably, affecting ship and plane traffic. Banking and financial networks could go offline, disrupting commerce in ways unimagined in the 1850s. According to a 2008 report from the National Academy of Sciences, a century-class solar storm could have the economic impact of 20 hurricane Katrinas.

Moreover, there is nothing we can do to stop such an event. NASA researchers are trying to detect such events in time to warn civil authorities so action can be taken to minimize damage to sensitive infrastructure. In order to predict the weather in space analysts use data from a fleet of NASA spacecraft surrounding the Sun. Analysts feed the information into models running on supercomputers and, within hours of a major eruption, the computers generate a 3D movie showing where the storm will go, which planets and spacecraft it will hit, and when the impacts will occur. See the example animation by clicking on the figure below.

3D forecast-model of a coronal mass ejection. NASA.

“We can now track the progress of solar storms in 3 dimensions as the storms bear down on Earth,” says Michael Hesse, chief of the GSFC Space Weather Lab. “This sets the stage for actionable space weather alerts that could preserve power grids and other high-tech assets during extreme periods of solar activity.”

It may well be that a quiet Sun is more prone to infrequent but very large ejection events. According to NASA, the solar cycle of 1859 (Solar Cycle 10) was typical of 19th century solar cycles—that is to say, weak. Solar cycles of the 19th century were far below average compared to the intense solar cycles of the Space Age. With solar eruptions, as with climate change, we are helpless before the whims of nature. If anything, our modern technology has made us more vulnerable to nature’s rage.

The climate change Cassandra’s will insist that global warming is real and that we must do something about it. The real problem here is that scientists have never been able to study such phenomena before—at least not with satellites and modern instruments. Anyone who says they know what effect a prolonged period of solar inactivity would have on today’s clime is lying. We can make some inferences based on historical data, data collected by unreliable sources using primitive instruments. Those inferences seem to point to a cooler climate but this is just a guess. But it is a guess based on observations, no matter how dodgy, while the claims of global warming are based on fabrication.

Given the latest solar activity forecast, my suggestion is to do nothing. After all, if we are about to enter a period of global cooling the last thing we need is to try and make things cool still. If we do slip into a long term solar minimum, and given the observation that climate cooling lags solar quiescence by up to a decade, then we should have an answer regarding the Sun climate link in twenty years. So place your bets, CO2 or the Sun—I know which one I’m putting my money on.

Be safe, enjoy the interglacial and stay skeptical.

The Resilient Earth, 28 June 2011

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