“A new NASA study underscores the fact that greenhouse gases generated by human activity — not changes in solar activity — are the primary force driving global warming.”
Archive for the ‘SUN ACTIVITY’ Category
March 16, 2010 – Original Source: The Economic Times
WASHINGTON: A new study has determined that even if the sun commenced a very long period of low activity, it cannot put the brakes on the relentless rise of global temperatures caused by greenhouse gases.
Since the 13th century, the sun has gone through four “Grand Minima”, one of which is thought to have contributed to the anomalously low temperatures in Europe in the 17th and 18th centuries.
This extended cold period, known as the “Little Ice Age”, coincided with a very long period of calm on the solar surface.
Tracking sunspot numbers, astronomers noticed that from 1645 to 1715, the sun’s disk was “blank”, that is, it had few, if any, sunspots.
This period became known as the “Maunder Minimum”.
If the sun lacks spots, that means there is a reduction in magnetic energy, signifying a lower energy output, or a slight reduction in brightness, or “irradiance”.
Typically, every 11 years, the sun goes through peaks and troughs in energy output (known as solar maximum and minimum, respectively) and this abnormally long minima is largely attributed with contributing toward the Little Ice Age.
Solar minimum went on for a little longer than expected during Solar Cycle 24. Unfortunately, it didn’t help our warming climate much.
Scientists have pondered that if the sun endures another Grand Minimum, could the solar cycle slow down – or even reverse – the amplified global heating caused by greenhouse gas emissions.
“The notion that we are heading for a new Little Ice Age if the sun actually entered a Grand Minimum is wrong,” said study lead author Dr Georg Feulner of the Potsdam Institute for Climate Impact Research.
If greenhouse gas emissions continue to increase unchecked, global average temperatures are predicted to rise by between 3.7 degrees Celsius and 4.5 degrees Celsius by the end of the 21st century.
If the sun enters another Grand Minimum, the reduction in solar energy will slow heating by a paltry 0.3 degrees Celsius by the end of this century.
But, global warming will overwhelm any “cooling” effect caused by reduced solar output.
According to Julie Arblaster, a climate researcher at the Australian Bureau of Meteorology and the National Center for Atmospheric Research in Colorado, a reduction of 0.25 percent in solar irradiance is “on the extreme end of what we would expect for the next century.”
“This shows that any changes in the Sun, even large changes, will only have a small impact in offsetting that warming,” she said.
September 2, 2009 – Original Source: WIRED Science
On Sept. 2, 1859, at the telegraph office at No. 31 State Street in Boston at 9:30 a.m., the operators’ lines were overflowing with current, so they unplugged the batteries connected to their machines, and kept working using just the electricity coursing through the air.
In the wee hours of that night, the most brilliant auroras ever recorded had broken out across the skies of the Earth. People in Havana and Florida reported seeing them. The New York Times ran a 3,000 word feature recording the colorful event in purple prose.
“With this a beautiful tint of pink finally mingled. The clouds of this color were most abundant to the northeast and northwest of the zenith,” the Times wrote. “There they shot across one another, intermingling and deepening until the sky was painfully lurid. There was no figure the imagination could not find portrayed by these instantaneous flashes.”
As if what was happening in the heavens wasn’t enough, the communications infrastructure just beginning to stretch along the eastern seaboard was going haywire from all the electromagnetism.
“We observed the influence upon the lines at the time of commencing business — 8 o’clock — and it continued so strong up to 9 1/2 as to prevent any business from being done, excepting by throwing off the batteries at each end of the line and working by the atmospheric current entirely!” the astonished telegraph operators of Boston wrote in a statement that appeared in The New York Times later that week.
The Boston operator told his Portland, Maine counterpart, “Mine is also disconnected, and we are working with the auroral current. How do you receive my writing?” Portland responded, “Better than with our batteries on,” before finally concluding with Yankee pluck, “Very well. Shall I go ahead with business?”
In terms of the relationship between the Earth and its star, it is probably the weirdest 24-hours on record. People struggled to explain what had happened.
NASA’s David Hathaway, a solar astronomer, said that people in the solar community were beginning to understand that there was a relationship between events on the sun and magnetism on Earth. But that knowledge was not widely disseminated.
Another theory held that auroras were actually atmospheric phenomena, that is to say, weather of a particular type. Proof of various sorts was offered. Auroras apparently had a sound, “the noise of crepitation,” or crackling, that marked them as Earth-bound phenomena. Even weirder explanations arose, like meteorologist Ebenezer Miriam’s hilariously quacky quote in The New York Times.
“The Aurora (electricity discharged from the craters of volcanoes) either dissolves in the atmosphere, and is thus diffused through space or concentrated into a gelatineus[sic] substance forming meteors, called shooting stars,” Miriam wrote. “These meteors dissolve rapidly in atmospheric air, but sometimes reach the earth before dissolving, and resemble thin starch.”
But some scientists were on the right track. Eighteen hours before the storm hit, Richard Carrington, a young but well-respected British astronomer, had been making his daily sunspot observations when he saw two brilliant spots of light. We know now that what he was seeing was the heating up of the surface of the sun beyond its standard fusion-powered temperature of about 5,500 degrees Celsius. The energy to do so came from a magnetic explosion as a distended part of the sun’s magnetic field snapped and reconnected.
“They give off the energy equivalent of about 10 million atomic bombs in the matter of an hour or two,” Hathaway said. “[The 1859] one was special, and it was noticed because it was a white light flare. It actually heated up the surface of the sun well enough to light up the sun.”
Though back then Carrington didn’t know what he was looking at, five years of staring at the sun had taught him that what he was seeing was unprecedented. When in the wee hours of the next night, the skies all over the globe began turning brilliant colors, Carrington knew he was on to something.
“I think that it represents a tipping point in astronomy because for the first time, astronomers had concrete evidence that a force other than gravity could communicate itself across 93 million miles of space,” said Stuart Clark, author of the book The Sun Kings: The Unexpected Tragedy of Richard Carrington and the Tale of How Modern Astronomy Began.
Still, it would be decades before the scientific theory would catch up with the observations. British heavyweights like Lord Kelvin opined that the sun could never deliver the level of energy that had been observed on Earth. Understanding what was happening without understanding how the sun worked or the nature of particles was not exactly easy.
“It’s a great example of where theory and observation don’t match up,” Clark said. “The scientific establishment tends to believe the theory, but it’s usually the other way around, and the observations are correct. You have to build up a critical mass of observations to shift the scientific theory.”
Over time, more and more observations did shift the theory, and the sun was held properly responsible for geomagnetic storms. The technological lesson that electrical equipment could be disturbed was largely forgotten, though.
When a geomagnetic storm hits the Earth, it shakes the Earth’s magnetosphere. As the magnetized plasma pushes the Earth’s magnetic field lines around, currents flow. Those currents have their own magnetic fields and soon, down at the ground, strong electromagnetic forces are in play. In other words, your telegraph can run on “auroral current.”
Geomagnetic storms, though, can have less benign impacts. On August 4, 1972, a Bell Telephone line running from Chicago to San Francisco got knocked out. Bell Labs researchers wanted to find out why, and their findings led them right back to 1859 and the auroral current.
Louis Lanzerotti, now an engineering professor at the New Jersey Institute of Technology, went digging in the Bell Labs library for similar events and explanations. Along with field research, the history became the core of a new approach to building more robust electrical systems.
“We did all this analysis and wrote this paper in ‘74 for the Bell Systems Technical Journal,” Lanzerotti said. “And it really made a helluva of a difference in Bell Systems. They redesigned their power systems.”
The fight to secure the Earth’s technical systems from geomagnetic anomalies continues. Late last year, the National Academies of Science put out a report on severe space weather events. If a storm even approaching 1859 levels were to happen again, they concluded the damage could range upwards of a $1 trillion, largely because of disruptions to the electrical grid.
The data on how often huge storms occur is scarce. Ice cores are the main evidence we have outside human historical documents. Charged particles can interact with nitrogen in the atmosphere, creating nitrides. The increased concentration of those molecules can be detected by looking at ice cores, which act like a logbook of the atmosphere at a given time. Over the last 500 years of this data, the 1859 event was twice as big as anything else.
Even so, the sun remains a bit of a mystery, particularly these tremendously energetic events. Scientists like Hathaway are able to describe why one geomagnetic storm might be bigger than another based on the details of how it arose, but they are hard pressed to predict when or why a freakishly large storm might arise.
Scientific understanding of how the sun impacts the Earth and its tech-heavy humans isn’t complete, but at least we know when it got its start: the early hours of September 2, 1859.
“It’s at that point we realize that these celestial objects affected our technologies and the way we wanted to live our lives,” Stuart said.
And it turns out, our burning hot star still does.