What Caused The Spotless Sun?
Beginning in 2008, sunspots almost completely disappeared for two years. Solar activity dropped to hundred-year lows and the Sun’s magnetic field weakened, allowing cosmic rays to penetrate the Solar System in record numbers. More troubling, Earth's upper atmosphere cooled and collapsed by an unprecedented amount. Solar physicists openly wondered what was happening to our neighborhood star. Now, an international team of scientists funded by NASA claims to have figured out what was going on. Their explanation was just published in the March 3, 2011, edition of Nature.
The almost complete absence of sunspots during the last prolonged solar minimum has been a puzzlement to scientists around the world. There has been much speculation regarding the link between solar activity, sunspots and Earth's climate. From historical records, scientists have found a strong correlation between low sunspot activity and a cooling climate. Now a new paper, “The unusual minimum of sunspot cycle 23 caused by meridional plasma flow,” reveals that science may be closer to being able to accuratly predict solar cycles.
During the the famous Little Ice Age, a prolonged period of cold weather that afflicted the world for centuries and didn't end until just prior to the American Civil War, the Sun was also abnormally quiet with sunspots disappearing for years at a time. Given the recent harsh winters experienced around the world, many weather forecasters are wondering if we have entered a new Little Ice Age.
Sunspot cycles over the last century.
It is true that, during long solar minima, strange things happen. Most recently, during 2008-2009, the Sun’s magnetic field weakened and the solar wind subsided. This allowed cosmic rays, normally held at bay by the Sun’s out-flowing particle wind and magnetism surged, into the inner solar system. Counter intuitively, space during the recent solar minimum became a more dangerous place to travel.
At the same time, the heating action of UV rays normally provided by sunspots was also absent, leading Earth’s upper atmosphere, the thermosphere, to cool and collapse. The thermosphere always cools and contracts when solar activity is low. In this case, however, the magnitude of the collapse was two to three times greater than the low solar activity could explain.
“Something is going on that we do not understand,” said John Emmert of the Naval Research Lab, regarding the atmospheric contraction. Emmert was lead author of a paper announcing that finding in the June 19, 2010, issue of the Geophysical Research Letters. “It's a Space Age record.”
With the contracting upper atmosphere, the orbits of space junk stopped decaying as rapidly as usual. Dead satellites and discarded rocket parts began accumulating in Earth orbit. Here on Earth, changing upper atmosphere dynamics may have contributed to the Arctic oscillation that has brought such wicked winter weather to the Northern Hemisphere in recent years.
Solar physicists have recognized the importance of the Sun's “Great Conveyor Belt” for decades. A vast system of plasma currents called meridional flows travel along the Sun's surface. Similar to ocean currents in Earth's oceans, the plasma plunges inward around the poles, and rises up again near the Sun's equator. Scientists think these looping currents play a key role in the 11-year solar cycle. When sunspots begin to decay, surface currents sweep up their magnetic remains and pull them down inside the star; 300,000 km below the surface, the Sun’s magnetic dynamo amplifies the decaying magnetic fields. The reinvigorated sunspots become buoyant and return to the surface—A new solar cycle is born.
For the first time, a team of scientists, funded by NASA’s Living With a Star Program and the Department of Science and Technology of the Government of India, believes they have developed a computer model that correctly reflects reality. To do so, the model must accurately simulate the physics of three principle factors driving the solar environment: the magnetic dynamo, the conveyor belt, and the buoyant evolution of sunspot magnetic fields. News of these developments was reported on the NASA website.
“Plasma currents deep inside the sun interfered with the formation of sunspots and prolonged solar minimum,” says lead author Dibyendu Nandi of the Indian Institute of Science Education and Research. “Our conclusions are based on a new computer model of the sun's interior.”
“According to our model, the trouble with sunspots actually began in back in the late 1990s during the upswing of Solar Cycle 23,” says co-author Andrés Muñoz-Jaramillo of the Harvard-Smithsonian Center for Astrophysics. “At that time, the conveyor belt sped up.”
The fast-moving belt rapidly dragged sunspots down to Sun's inner dynamo for amplification. It might seem that this would boost sunspot production, but when the remains of old sunspots reached the dynamo, they rode the belt through the amplification zone too quickly for full re-animation. Sunspot production actually diminished.
Cutaway view of the Sun.
According to the model, the Conveyor Belt slowed down again later in the 2000s, allowing magnetic fields to spend more time in the amplification zone, but the damage was already done. New sunspots were in short supply. Additionally, the slow moving belt did little to assist re-animated sunspots on their journey back to the surface, delaying the onset of Solar Cycle 24. The conditions were right for a very deep and prolonged solar minimum.
While a solar maximum is relatively brief, lasting a few years punctuated by episodes of violent flaring that last only days, a solar minimum can last for many years. Previous efforts at predicting the strength and duration of solar minimums have met with mixed success. Colleagues are calling the team's new model a great advancement in understanding solar dynamics. A better understanding of solar cycles may, in fact, have important implications for climate change. The correlation between sunspots and temperature is quite pronounced, with climate following sunspot activity much better than recent charts of fluctuating temperatures vs. steadily increasing CO2.
All of this reinforces observations by other researchers who have found substantive connections between solar cycles and climate change. Though the Sun's output varies by less than a tenth of a percent in magnitude during its 11-year sunspot cycle, that small variation produces changes in sea surface temperatures two or three times as large as it should (see “Atmospheric Solar Heat Amplifier Discovered”). Other studies have found that, though visible sunlight intensity doesn't vary by much, the extreem UV frequencies can change by as much a 6%. The quiet Sun of 2008 and 2009 has again demonstrated that the single most important factor in Earth's climate is the source of energy that drives it—the Sun.
This does not set well with the “blame global warming on human CO2 emissions” types who continue to claim center stage in the ongoing climate change catastrophe scam. This is the same school of thought that funds the IPCC and disinformation specialists like Michael Mann and James Hansen. While people like those at GISS, who stare at computer models instead of the real world, have sullied NASA's reputation, the work here shows that there are still some real scientists at the US space agency.
Ever wonder what causes global warming?
No matter, climate change alarmists continue to discount changes in solar output as a cause of global warming. While Hansen and his consensus science clown posse continue to blame any change in climate on CO2, others have found more believable causes, like fluctuating solar EUV radiation and the disproportionate effect it has on Earth's upper atmosphere. If you want to know what really causes climate change look up—just remember to wear dark glasses and some sunblock.
Be safe, enjoy the interglacial and stay skeptical.