Maybe mother nature is going to give us a second chance .
"Global warming: Will the Sun come to our rescue? "
18 September 2006
Stuart Clark
http://www.newscientist.com
*
entire article can be seen with subscription at:
http://www.newscientist.com/channel...me-to-our-rescue.html;jsessionid=FBDBFNBLALAI
below are excerpts from article:
"It is known as the Little Ice Age. Bitter winters blighted much of the northern hemisphere for decades in the second half of the 17th century. The French army used frozen rivers as thoroughfares to invade the Netherlands. New Yorkers walked from Manhattan to Staten Island across the frozen harbour. Sea ice surrounded Iceland for miles and the island's population halved. It wasn't the first time temperatures had plunged: a couple of hundred years earlier, between 1420 and 1570, a climatic downturn claimed the Viking colonies on Greenland, turning them from fertile farmlands into arctic wastelands.
Could the sun have been to blame? We now know that, curiously, both these mini ice ages coincided with prolonged lulls in the sun's activity - the sunspots and dramatic flares that are driven by its powerful magnetic field.
Now some astronomers are predicting that the sun is about to enter another quiet period. With climate scientists warning that global warming is approaching a tipping point, beyond which rapid and possibly irreversible damage to our environment will be unavoidable, a calm sun and a resultant cold snap might be exactly what we need to give us breathing space to agree and enact pollution controls. "It would certainly buy us some time," says Joanna Haigh, an atmospheric physicist at Imperial College London.
Global average temperatures have risen by about 0.6 ?C in the past century, and until recently almost all of this has been put down to human activity. But that may not be the only factor at work. A growing number of scientists believe that there are clear links between the sun's activity and the temperature on Earth. While solar magnetic activity cannot explain away global warming completely, it does seem to have a significant impact. "A couple of years ago, I would not have said that there was any evidence for solar activity driving temperatures on Earth," says Paula Reimer, a palaeoclimate expert at Queen's University, Belfast, in the UK. "Now I think there is fairly convincing evidence."
What has won round Reimer and others is evidence linking climate to sunspots. These blemishes on the sun's surface appear and fade over days, weeks or months, depending on their size. More than a mere curiosity, they are windows on the sun's mood. They are created by contortions in the sun's magnetic field and their appearance foretells massive solar eruptions that fling billions of tonnes of gas into space. Fewer sunspots pop up when the sun is calm, and historically these periods have coincided with mini ice ages.
The number of sunspots and solar magnetic activity in general normally wax and wane in cycles lasting around 11 years, but every 200 years or so, the sunspots all but disappear as solar activity slumps (see "Field feedback") . For the past 50 years, on the other hand, the sun has been particularly restless. "If you look back into the sun's past, you find that we live in a period of abnormally high solar activity," says Nigel Weiss, a solar physicist at the University of Cambridge.
Cosmic correlation
..."Periods of high solar activity do not last long, perhaps 50 to 100 years, then you get a crash," says Weiss. "It's a boom-bust system, and I would expect a crash soon."
... The sun's polar field is now at its weakest since measurements began in the early 1950s, and to Svalgaard, the latest figures indicate that the sun's activity will be weaker during the next decade than it has been for more than 100 years. "Sunspot numbers are well on the way down in the next decade," he predicts. He expects fewer than six new sunspots per month, less than half the average number seen over the past decade.
This is hardly the sunspot crash that observations from 1645 to 1715 suggest. Back then, the appearance of even a single sunspot was major astronomical news, sparking hurriedly penned communications from one observatory to another. Nevertheless, it's a sign of things to come. "Sunspot numbers will be extremely small, and when the sun crashes, it crashes hard," says Svaalgard.
?The upcoming sunspot crash could cause the Earth to cool ?
No room for complacency
The coming years could settle the sun's role on temperatures once and for all. If the expected sunspot crash does takes place, Solanki's work could receive dramatic confirmation. "Having a crash would certainly allow us to pin down the sun's true level of influence on the Earth's climate," says Weiss.
None of this means that we can stop worrying about global warming caused by emissions into the atmosphere. "The temperature of the Earth in the past few decades does not correlate with solar activity at all," Solanki says. He estimates that solar activity is responsible for only 30 per cent, at most, of the warming since 1970. The rest must be the result of man-made greenhouse gases, and a crash in solar activity won't do anything to get rid of them.
What might happen is that the sun gives the planet a welcome respite from the ravages of man-made climate change - though for how long, nobody knows. During the Little Ice Age, the fall in average global temperature is estimated to have been less than 1 ?C and lasted 70 years. The one before that persisted for 150 years, but a minor crash at the beginning of the 19th century lasted barely 30. For now, we will have to keep watching for falling sunspot numbers. "The deeper the crash, the longer it will last," Weiss says.
There is a dangerous flip side to this coin. If global warming does slow down or partially reverse with a sunspot crash, industrial polluters and reluctant nations could use it as a justification for turning their backs on pollution controls altogether, makingmatters worse in the long run. There is no room for complacency, Svalgaard warns: "If the Earth does cool during the next sunspot crash and we do nothing, when the sun's magnetic activity returns, global warming will return with a vengeance." "
From issue 2569 of New Scientist magazine, 18 September 2006, page 32-36
"Global warming: Will the Sun come to our rescue? "
18 September 2006
Stuart Clark
http://www.newscientist.com
*
entire article can be seen with subscription at:
http://www.newscientist.com/channel...me-to-our-rescue.html;jsessionid=FBDBFNBLALAI
below are excerpts from article:
"It is known as the Little Ice Age. Bitter winters blighted much of the northern hemisphere for decades in the second half of the 17th century. The French army used frozen rivers as thoroughfares to invade the Netherlands. New Yorkers walked from Manhattan to Staten Island across the frozen harbour. Sea ice surrounded Iceland for miles and the island's population halved. It wasn't the first time temperatures had plunged: a couple of hundred years earlier, between 1420 and 1570, a climatic downturn claimed the Viking colonies on Greenland, turning them from fertile farmlands into arctic wastelands.
Could the sun have been to blame? We now know that, curiously, both these mini ice ages coincided with prolonged lulls in the sun's activity - the sunspots and dramatic flares that are driven by its powerful magnetic field.
Now some astronomers are predicting that the sun is about to enter another quiet period. With climate scientists warning that global warming is approaching a tipping point, beyond which rapid and possibly irreversible damage to our environment will be unavoidable, a calm sun and a resultant cold snap might be exactly what we need to give us breathing space to agree and enact pollution controls. "It would certainly buy us some time," says Joanna Haigh, an atmospheric physicist at Imperial College London.
Global average temperatures have risen by about 0.6 ?C in the past century, and until recently almost all of this has been put down to human activity. But that may not be the only factor at work. A growing number of scientists believe that there are clear links between the sun's activity and the temperature on Earth. While solar magnetic activity cannot explain away global warming completely, it does seem to have a significant impact. "A couple of years ago, I would not have said that there was any evidence for solar activity driving temperatures on Earth," says Paula Reimer, a palaeoclimate expert at Queen's University, Belfast, in the UK. "Now I think there is fairly convincing evidence."
What has won round Reimer and others is evidence linking climate to sunspots. These blemishes on the sun's surface appear and fade over days, weeks or months, depending on their size. More than a mere curiosity, they are windows on the sun's mood. They are created by contortions in the sun's magnetic field and their appearance foretells massive solar eruptions that fling billions of tonnes of gas into space. Fewer sunspots pop up when the sun is calm, and historically these periods have coincided with mini ice ages.
The number of sunspots and solar magnetic activity in general normally wax and wane in cycles lasting around 11 years, but every 200 years or so, the sunspots all but disappear as solar activity slumps (see "Field feedback") . For the past 50 years, on the other hand, the sun has been particularly restless. "If you look back into the sun's past, you find that we live in a period of abnormally high solar activity," says Nigel Weiss, a solar physicist at the University of Cambridge.
Cosmic correlation
..."Periods of high solar activity do not last long, perhaps 50 to 100 years, then you get a crash," says Weiss. "It's a boom-bust system, and I would expect a crash soon."
... The sun's polar field is now at its weakest since measurements began in the early 1950s, and to Svalgaard, the latest figures indicate that the sun's activity will be weaker during the next decade than it has been for more than 100 years. "Sunspot numbers are well on the way down in the next decade," he predicts. He expects fewer than six new sunspots per month, less than half the average number seen over the past decade.
This is hardly the sunspot crash that observations from 1645 to 1715 suggest. Back then, the appearance of even a single sunspot was major astronomical news, sparking hurriedly penned communications from one observatory to another. Nevertheless, it's a sign of things to come. "Sunspot numbers will be extremely small, and when the sun crashes, it crashes hard," says Svaalgard.
?The upcoming sunspot crash could cause the Earth to cool ?
No room for complacency
The coming years could settle the sun's role on temperatures once and for all. If the expected sunspot crash does takes place, Solanki's work could receive dramatic confirmation. "Having a crash would certainly allow us to pin down the sun's true level of influence on the Earth's climate," says Weiss.
None of this means that we can stop worrying about global warming caused by emissions into the atmosphere. "The temperature of the Earth in the past few decades does not correlate with solar activity at all," Solanki says. He estimates that solar activity is responsible for only 30 per cent, at most, of the warming since 1970. The rest must be the result of man-made greenhouse gases, and a crash in solar activity won't do anything to get rid of them.
What might happen is that the sun gives the planet a welcome respite from the ravages of man-made climate change - though for how long, nobody knows. During the Little Ice Age, the fall in average global temperature is estimated to have been less than 1 ?C and lasted 70 years. The one before that persisted for 150 years, but a minor crash at the beginning of the 19th century lasted barely 30. For now, we will have to keep watching for falling sunspot numbers. "The deeper the crash, the longer it will last," Weiss says.
There is a dangerous flip side to this coin. If global warming does slow down or partially reverse with a sunspot crash, industrial polluters and reluctant nations could use it as a justification for turning their backs on pollution controls altogether, makingmatters worse in the long run. There is no room for complacency, Svalgaard warns: "If the Earth does cool during the next sunspot crash and we do nothing, when the sun's magnetic activity returns, global warming will return with a vengeance." "
From issue 2569 of New Scientist magazine, 18 September 2006, page 32-36
