Posted on 09/13/2006 2:01:24 PM PDT by Ernest_at_the_Beach
OSLO (Reuters) - The sun's energy output has barely varied over the past 1,000 years, raising chances that global warming has human rather than celestial causes, a study showed on Wednesday.
Researchers from Germany, Switzerland and the United States found that the sun's brightness varied by only 0.07 percent over 11-year sunspot cycles, far too little to account for the rise in temperatures since the Industrial Revolution.
"Our results imply that over the past century climate change due to human influences must far outweigh the effects of changes in the sun's brightness," said Tom Wigley of the U.S. National Center for Atmospheric Research.
Most experts say emissions of greenhouse gases, mainly from burning fossil fuels in power plants, factories and cars, are the main cause of a 0.6 Celsius (1.1 F) rise in temperatures over the past century.
A dwindling group of scientists says that the dominant cause of warming is a natural variation in the climate system, or a gradual rise in the sun's energy output.
"The solar contribution to warming over the past 30 years is negligible," the researchers wrote in the journal Nature of evidence about the sun from satellite observations since 1978.
They also found little sign of solar warming or cooling when they checked telescope observations of sunspots against temperature records going back to the 17th century.
They then checked more ancient evidence of rare isotopes and temperatures trapped in sea sediments and Greenland and Antarctic ice and also found no dramatic shifts in solar energy output for at least the past millennium.
SUN NOT GUILTY
"This basically rules out the sun as the cause of global warming," Henk Spruit, a co-author of the report from the Max Planck Institute in Germany, told Reuters.
Many scientists say greenhouse gases might push up world temperatures by perhaps another 3 Celsius by 2100, causing more droughts, floods, disease and rising global sea levels.
Spruit said a "Little Ice Age" around the 17th century, when London's Thames River froze, seemed limited mainly to western Europe and so was not a planet-wide cooling that might have implied a dimmer sun.
And global Ice Ages, like the last one which ended about 10,000 years ago, seem linked to cyclical shifts in the earth's orbit around the sun rather than to changes in solar output.
"Overall, we can find no evidence for solar luminosity variations of sufficient amplitude to drive significant climate variations on centennial, millennial or even million-year timescales," the report said.
Solar activity is now around a low on the 11-year cycle after a 2000 peak, when bright spots called faculae emit more heat and outweigh the heat-plugging effect of dark sunspots. Both faculae and dark sunspots are most common at the peaks.
Still, the report also said there could be other, more subtle solar effects on the climate, such as from cosmic rays or ultraviolet radiation. It said they would be hard to detect.
See this:
*******************
But Jerry Goldstein of the Southwest Research Institute in San Antonio, Anthea Coster of MITs Haystack Observatory in Westford, Massachusetts, and Toni Mannucci of NASAs JPL in Pasadena, California, used the receivers to measure conditions in the ionosphere--the layer of the atmosphere where the Suns ultraviolet light kicks electrons away from their atoms and leaves positively charged ions behind.
The ionospheres electric fields delay GPS radio signals as they pass from satellites to receivers. By comparing the different delays of GPS signals with different frequencies, the researchers calculated how many charged particles the signals passed on their way to the receiver. In other words: they measured the thickness of the ionosphere.
Charged particles also play the lead role in geomagnetic storms. During these storms, the Sun spews out a part of its outer layer, which may head toward Earth. This hot cloud of electrons and ions--plasma--then collides with Earths doughnut-shape magnetic field.
This collision deforms the cocoon and blows away part of its plasma as a long, tapering plume.
Geomagnetic storms can have noticeable consequences on Earth. On the ground, the changing magnetic field can induce damaging voltages in long power lines. In the ionosphere it can a deteriorate of the quality of radio broadcasts.
While monitoring the state of the ionosphere all over the globe during a couple of storms in 2001 and 2003, Coster and her colleagues discovered this disruption of the ionosphere is far from chaotic.
Changes in Earths magnetic field, which stays connected to the plume as it is pushed away, cause powerful electric fields in the outer layers of the atmosphere. An electric footprint of the plume drags over the ionosphere, much like a cold front moves through a weather system.
When such a disturbance occurs over North America, it takes the form of a southeast-to-northwest corridor, a few hundred miles wide, where radio reception suffers. Along its edges, GPS readings may be off by tens of yards instead of just a few.
Inner Magnetospheric Shielding, Penetration Electric Field, and the Plasmasphere
**************************************
Conclusions
The plasmasphere is the torus of cold, dense, co-rotating plasma surrounding the Earth out to 3-5 RE, and is populated by ionospheric outflow.
The plasmapause is the outer boundary of the plasmasphere, but does not need to coincide with the instantaneous boundary between convection and co-rotation (the last closed equipotential or LCE), because the time scale for plasmaspheric response is slower than the time scale of convection variations.
Plasmaspheric tails form during periods of high activity (Kp high, or Dst low), and extend all the way down to the ionosphere. (They can therefore affect Earth communications.)
The inner magnetosphere tries to shield itself from the convection E-fields, but the buildup of an effective shielding layer takes time. If the convection strength varies faster than the shielding time scale (somewhere between 15 minutes and an hour), E-fields can penetrate past the shielding layer, and into the inner magnetosphere.
Penetration E-fields can affect both plasmaspheric populations (forming meso-scale structure such as tails, shoulders and/or bite-outs), and ring current distributions.
What is their explanation, I wonder, for all the fears of Global COOLING back in the 70s?
*******************************************
Sun Not Off the Hook for Warming
The authors and other experts are quick to point out that more complicated solar mechanisms could possibly be driving climate change in ways we don't yet understand.
Climate change carries such high stakes that even more unlikely possibilities may capture scientific attention.
"There are numerous studies that find a correlation [between solar variation and Earth climate]," said Sami Solanki of the Max Planck Institute for Solar System Research in Lindau, Germany.
"These authors have looked at the simplest mechanism, and they find that this mechanism does not produce the same level of change that has been observed," he continued.
"This could be suggesting that there are other mechanisms acting for the way that the sun influences climate."
Solar ultraviolet (UV) rays are one possibility, though that theory creates its own challenges.
"UV is only a small fraction of total solar output, so you'd need a strong amplification mechanism in the Earth's atmosphere," study co-author Spruit said.
Magnetized plasma flares known as solar wind could also impact Earth's climate. Solar wind influences galactic rays and may in turn affect atmospheric phenomena on Earth, such as cloud cover.
Such complex interactions are poorly understood but could be crucial to unlocking Earth's climatic puzzle.
***********************************************
Goldstein has studied the impact solar flares have on earth communications which are heavily impacted by the disappearance of the outer shield....it's not a big jump in reasoning to see that without the shielding,....particles from outer space reach deeper into the atmosphere....
I think it has something to do with Research Grants.....
I think the reason for the study is to compare sunspot activity to other indications of solar output to see if they correlate.
The global warming angle is just a pr gimmick I hope.
*That* was one of the best smackdowns ever.
You must be highly religious, as you are unable to admit being wrong. A credit to your faith.
Before I got to that point I was wondering if these guys had studied ultraviolet emissions ~ apparantly they hadn't.
Not humans, but their SUVs
Whoops. Wrong thread.
Right.
After being humiliated, AND after your comment about the hissy fit.
After running naked through the room it's a bit late to put your clothes on.
Why do you reject the effect of cosmic rays on cloud cover since we have seen a clear correlation with cosmic ray flux and cloud cover and also with cosmic rays and high altitude temperature?
But there is a good correlation between sunspots and earth's temperature.
Thank you.
I regret to inform you that your hissy fit did not actually achieve victory.
Question the church of gaia and the apostles flame without mercy.
What are you babbling about here? Oh, right, I point out that you're being stupid about something, and automatically that makes me an "apostle" of the "church of gaia", because no one could possibly correct your errors unless they're a whackjob environmentalist, right?
Is this what passes for "thought" on your planet? Are you always this delusional and willing to jump to wild and false conclusions, or are you just having a bad day?
Let's see if you're honorable enough to retract your false accusation and admit your error about me, or whether you're just going to bluster and namecall some more because you're not mature enough to admit you're posting your wild presumptions as facts.
You might also want to explain why you're so cowardly that you didn't ping me to your snide little insult about me, despite the fact that you were responding directly to my post #54. Man, talk about "hissy fits"...
The verbage was good, an 8.5, but it was the illustrations that pushed you to a perfect 10.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.