The idea that sunspot-related solar variability influences Earth’s environment is frequently attributed to an early nineteenth-century British astronomer by the name of William Herschel. His observation was that a relatively high number of sunspots correlated to larger wheat crops, and lower prices. Although his study was widely mocked, peer-reviewed research in the last decade has partly borne out his hunches. The European Space Agency named its new satellite observatory after Herschel in May 2009.
At the turn of the 20th century, another English astronomer, Edward Maunder, conducted a ground-breaking study of solar cycles. He was especially interested in periods of low sunspot activity, such as those that took place from 1420 to 1550 and from 1645 to 1715. Although completely ignored by his peers, Maunder’s work was eventually built upon in the 1970s by an American solar physicist by the name of Jack Eddy. Eddy studied solar cycles extensively himself, and matched carbon-dated temperature proxies with them, to good effect. It was Eddy who labeled the coldest period during the Little Ice Age the Maunder Minimum, and his work has been influential. NASA graphs of past sunspot cycles that include the Little Ice Age typically now show the Maunder Minimum.
NASA has been taking measurements of solar activity since the early 1970s, initially in preparation for a mission known as Skylab. The two leading reasons for the agency’s interest in solar science are: (a) the amount of radiation that astronauts are exposed to, which rises and falls with the solar cycle and (b) those who run telecommunications networks and power grids require advance warning of solar storming, which can bring down both kinds of systems. In the three decades since Skylab was put into space, curiosity about the Sun’s effect on climate here on Earth has evolved for many working at the agency. In 1990, James Hansen wrote that “comparisons of available data show that solar variability will not counteract greenhouse warming.” Conversely, in 2009, he wrote, “it is likely that the sun is an important factor in climate variability.” As Hansen moved toward this shift in perspective, a Russian space program scientist had come out swinging, boldly predicting that Hansen’s forecasted warming during the next half-century would simply not come to pass.
In a 2007 interview with the Russian news agency RIA Novosti, Habibullo Abdussamatov, the head of the solar science wing of the Russian space program, said that a grand solar maximum had recently ended and the consequences would be apparent soon. “Instead of professed global warming, the Earth will be facing a slow decrease in temperatures in 2012-2015,” he said. “The gradually falling amounts of solar energy, expected to reach their bottom level by 2040, will inevitably lead to a deep freeze around 2055-2060.” He stated that the recent uptick in global mean temperature “results not from the emission of greenhouse gases into the atmosphere, but from an unusually high level of solar radiation and a lengthy – almost throughout the last century – growth in its intensity.” Abdussamatov was joined by several solar physicists in noting the high level of solar activity during the last several decades. Sami Solanki published a paper in 2004 entitled “Unusual activity of the Sun during recent decades compared to the previous 11,000 years.” In it, he argues that the Modern Maximum was the greatest period of solar activity during the Holocene, by a wide margin. For his part, Abdussamatov went on record that he thought conventional notions about global warming were mistaken: “[T]he common view that man’s industrial activity is a deciding factor in global warming has emerged from a misinterpretation of cause and effect relations.”
Several features are worth mention: (1) The Maunder Minimum from 1645 to 1700, during which sunspots ceased to be visible on the Sun and temperatures on Earth were the lowest they had been since the last full-fledged ice age; (2) the Dalton Minimum from about 1790 until about 1830, during which temperatures on Earth fell again; and the high number of sunspots during the grand solar maximum of the middle to late twentieth century, when temperatures on Earth rose to their highest levels since the Medieval Warm Period. Over the past few decades, solar physics has drawn more researchers into its controversy-laden midst.
In the meantime, the peaks and valleys in historical solar activity, made decipherable through a combination of direct and indirect measurement, have all received names. For the quiet periods, they are: the Oort, which took place between 1040 and 1080; the Wolf, which took place between 1280 and 1350; the Spörer, which took place from 1420 to 1550; the Maunder, which took place from 1645 to 1715; and the Dalton, which took place from 1790 to 1820. The named periods of high activity are: the Medieval Maximum, from 1100 to 1250; and the Modern Maximum, which began in 1950 and ended in 2006. The Sun-Earth climate connection scientists avow that the named solar minima, starting with the Wolf and ending with the Dalton, were almost surely among the causes of the Little Ice Age. What Abdussamatov was claiming was that a repeat of the Maunder Minimum was upon us, with similar kinds of cooling in our immediate future.
Another factor that may have altered Hansen’s views was the development of theories about secondary solar effects, especially one by Henrik Svensmark. In a campaign to find the holy grail of climatology, something that could explain many of the ups and downs during the Holocene as well as over the course of deep geologic time, Svensmark had come up with a mechanism that included cosmic rays. Scientists who said that the Sun’s main output of energy was far too constant to explain significant climate variation on Earth were failing to take into account knock-on effects, specifically that cloud production was largely regulated by the Sun’s influence on cosmic rays, Svensmark and those in his camp have maintained that more clouds should produce cooler temperatures. Probably more significant in terms of convincing the doubters to at least pay lip service to the importance of solar variability, the Sun had begun to do what Abdussamatov had said it would, by entering a prolonged minimum, the deepest in at least a century.
Somewhat ironically, as the downturn in solar activity began, physicists at NASA (not the wing overseen by Hansen) were forecasting a period of intense solar activity. In March 2006, as the solar cycle began winding down, NASA, on behalf of its solar physicists, put out a somewhat breathless press release claiming that the coming cycle was going to be “a doozy.” The release focused on a National Center for Atmospheric Research scientist named Mausumi Dikpati who said that the high level of solar activity during the last half of the twentieth century was about to be built upon. “The next sunspot cycle will be 30 to 50 percent stronger than the previous one,” Dikpati said. Basing her prediction on something called the “solar dynamo” theory, in which a “conveyor belt” moving magnetic fields from the poles toward the Sun’s equator drives sunspot formation, Dikpati and her team also relied heavily on computer modeling. NASA’s own leading solar physicist David Hathaway, concurred with Dikpati that the coming cycle would be significant, predicting a number of sunspots among the highest ever seen. The only exception Hathaway took with Dikpati was on the timing. “History shows that big sunspot cycles ‘ramp up’ faster than small ones,” he said. The next two years were anything but kind to Hathaway and Dikpati, however, as the old cycle showed no sign of ending and the new cycle no sign of starting. In what some labeled punting, Hathaway reissued predictions every several months, but kept with his overall view that a strong cycle was on the way.
As U.S. and Russian space-program physicists took part in a tacit competition to anticipate what the Sun would do in the coming decades, the Space Race of the 1950s and ’60s was arguably being played out anew. Unlike the first time, the competition was being held out of public view, with the countries’ best physicists, Hathaway, Hansen, and Abdussamatov among them, trading blows in academic journals. This time around, the terms of the debate were not rocket-booster fuel formulae, re-entry material construction, and orbital equations, but, rather, where the planet was headed climatologically. Jack Eddy, at the end of his life, was paying attention to the Sun’s doings. “We’re at a prolonged minimum now, of which there have been precedents,” he said in 2008, months before his passing. “Whether we’re going to go into one of these profound minima or not, we won’t know until we get there. It might make me famous if it happens, but I don’t see that we know that it will happen.” Eddy’s work has been cited by Abdussamatov, and indeed calls have been issued for the naming of the forthcoming minimum, should it be as prolonged as some anticipate, as the Eddy Minimum. It is a matter of some irony that a Russian scientist following his research to its logical conclusion appears to have greater intellectual freedom than most of his American counterparts, with the notable exception of Jack Eddy.
In the United States, meanwhile, on the heels of Al Gore’s triumphant Academy Award for Best Documentary and Nobel Peace Prize, skeptical views on “climate change” were being belittled as fringe, corrupt, or worse. Despite centuries’ worth of research into the subject, talking about sunspots, and any putative effect on Earth’s climate, was clearly still a good way to raise eyebrows. In other words, a low-level Inquisition continued. NASA, as an example, found itself institutionally compelled to allude to the Sun-Earth climate connection and then to dismiss such talk as mumbo-jumbo, sometimes at the same press conference. As NASA scientists watched the pace of the transition between the outgoing and incoming solar cycles with increasingly nervous eyes, a December 2007 press release underlined expectations for a powerful new cycle: Many forecasters believe Solar Cycle 24 will be big and intense. Peaking in 2011 or 2012, the cycle to come could have significant impacts on telecommunications, air traffic, power grids and GPS systems. (And don’t forget the Northern Lights!) In this age of satellites and cell phones, the next solar cycle could make itself felt as never before. An implicit plea for continued funding could hardly be mistaken.
While James Hansen and his NASA climatology team depend for their high level of funding on the perception that manmade global warming is a threat to humanity’s continued existence, the agency’s solar physicists have less widely known threats upon which to pin their funding hopes. The two groups, meanwhile, stood to help each other, if they could convince Congress and the public, with their respective expertise, that only CO2 could have produced the recent warming. A Sun that was not on the verge of a major shift in activity was one stone in the foundation of the argument. Just over a year later, the agency’s jaunty tone had shifted to one that was more defensive about the now visibly lingering solar minimum. A new press release bore the headline “What’s Wrong with the Sun? (Nothing),” and was laced with reasons why the gap between sunspot cycles wasn’t unusual at all. “It does seem like it’s taking a long time, but I think we’re just forgetting how long a solar minimum can last,” Hathaway said. Past lengthy minima had taken place before, the press released explained, helpfully adding: “Most researchers weren’t even born then.”
NASA’s reputation in general, and Hathaway’s in particular, meanwhile, were being harmed by the Sun’s failure to cooperate, and Abdussamatov was beginning to look increasingly prescient. As the minimum continued, with sunspots coming in fewer numbers and all other indices declining as well, a press conference in October 2008 in which Hathaway did not take part tried to correct the public perception that the entire agency had been caught flat-footed. The Ulysses space mission launched in 1990 had been collecting solar data, a team of NASA physicists explained, that corroborated the fact that the current solar minimum was the deepest of the satellite era, with the weakest solar wind during the past 50-plus years. Among the mission scientists participating in the news conference was Nancy Crooker, who said the following: The length and depth of the current minimum is fully within the norm of the last two hundred years, so it’s not unusual in that regard. But it is unique in the space age. We also know that the Sun entered an extended minimum during the second half of the 17th century, but that’s not likely to happen. Just yesterday, there was a significant sunspot emerging, and that’s a good sign that we’re moving into the next solar cycle. Agency anxiety that the solar influence on climate would be brought to light was discernible in Crooker’s every word, and yet, of the panel of five scientists speaking, she was the most open to discussing the Sun-Earth climate connection. The sunspot to which she referred did not prove to be any kind of ramp-up point, however, as solar activity returned to its previous low levels within days.
Around the time of the press conference featuring his agency colleagues, Hathaway withdrew from the NASA Solar Cycle committee that he, until that point, had chaired. The discussions, he said, had grown “too hot.” Probably more significant, he moved away not only from his prediction of a strong Solar Cycle 24 but from the governing model of the Sun. “I have to admit that the last two months have been really disappointing,” he said. “I have become increasingly worried about the conveyor belt and its role in the sunspot cycle and in the prediction of sunspot cycles.” In June 2009, after several more NASA press releases observing that the new solar cycle had yet to pick up meaningful momentum, a new optimistic release was put forth: “Mystery of the Missing Sunspots, Solved?” The new theory was that a “solar jet-stream” had taken an extra year moving into position to start generating sunspots. Although the critical new research was not done by a NASA team, the agency was keen to announce that all was well. The lead researcher, Frank Hill, of the National Solar Observatory, was on top of the world. “It is exciting to see,” Hill said, “that just as this sluggish stream reaches the usual active latitude of twenty-two degrees, a year late, we finally begin to see new groups of sunspots emerging.” While spots were indeed beginning to show up with slightly greater frequency on the disk of the Sun, other major indices of solar activity remained low. Additionally, there was something curious about the new spots. They were vanishingly small, and unusually pale. The faint tones had been observed in increasing measure as long as fifteen years earlier by two other National Solar Observatory scientists, Matthew Penn and William Livingston. The two had attempted to get their observations of lower-contrast sunspots as well as analysis of the risk of a forthcoming Maunder-like minimum published, but with only partial success.
Although the magazine Science had published several other of Livingston’s papers, it declined to in this case, citing the short period of observation (about one solar cycle and a half). The Astrophysical Journal did accept two papers on these subjects from the pair, the first in 2006 and the second in 2007. If Livingston and Penn’s observations are correct and the trend of lighter sunspots continues, and late developments in June 2011 suggested that they were correct, then sunspots will become invisible by the year 2022, if not sooner. The magnetic phenomena that produces them would still be taking place, and the spots would still be there, they just wouldn’t be detectable in the visible spectrum of light. This may be what happened during the Maunder Minimum, and signal a grand solar minimum. Unfortunately, unlike Abdussamatov, Livingston and Penn do not have their president’s ear.
Although Barack Obama indicated when he became president that he would “restore science to its rightful place” in American society, to those who take the unknowns of solar influence on Earth’s climate seriously, the opposite has been the case. The pain caused by the president’s complicity in the silencing of skeptics is palpable among plenty of researchers who think that carbon dioxide’s power has been grossly exaggerated. Meanwhile, the effort to quiet skeptics has been extended to several continents. Among the scientists outside the U.S. who are wringing their hands is the Norwegian physicist Pål Brekke. “We could be in for a surprise,” Brekke stated in 2007. “It’s possible that the Sun plays an even more central role in global warming than we have suspected. Anyone who claims that the debate is over and the conclusions are firm has a fundamentally unscientific approach to one of the most momentous issues of our time.” While the Sun is not the only player in determining atmospheric temperature, acknowledging the Sun’s partial role together with changes in land use and ocean cycles would be a good start for the leader of the free world.
Amazon Kindle lets you highlight as much as 10% of book. And I found it was the only way to copy/paste excerpts from books I read.
This book is very good. However, it is not scientifically thorough like
is. If you really want to know your stuff, read that one. But if you want a more amusing, entertaining read, this is a good one.
I really had not known that the formal IPCC position on Sun-Earth Climate was that the Sun had minimal climatic effects. This sounds preposterous to me given the enormity of the Sun and the enormity of its internal dynamics. Intuitively, it would seem to me that the Sun would exert all kinds of cyclical climate patterns on the Earth, both directly and indirectly.
For example, one of the more interesting facts presented was the observation in the late 50's that an active Sun pushes cosmic rays away from the Earth. During low periods of solar activity, cosmic rays penetrate the earth's atmosphere and are now thought to have a significant effect on cloud formation.
Reading is good. You should all read. Even if the ideas are contrary.
