Re: Italy alarmed at early harvest of wine grapes

Yves Bellefeuille wrote:

Knight Of The Road wrote:

I read that scientists are predicting that
the world will start to cool in 2012 for the
next 50 years or so.
Example...
http://www.canada.com/nationalpost/new
/story.html?id=9e919563-e44b-4ca2-9706
8af9cf743c95

Oh, The National Pest. And the article is
by Terence Corcoran, no less.
Here's what The Pest says:

Global cooling effect: A report in New
Scientist magazine yesterday chronicles
the work of a crew of scientists who
forecast a new wave of global cooling
brought on by a decline in activity in the
sun."

Here's what New Scientist actually said:

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.

But in the very next sentence in the same paragraph he estimates up to
30% of the recent warming is caused by the Sun.

Any reason *not* to include that in your NS quote?
After all you are talking about Solar activity's effect on global
warming?
Regards, Walter

"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".

"...*Solanki* and his colleagues compared records of solar activity
derived from tree rings with meteorological records from 1856 to the
present day. They found that the temperature of the Earth's atmosphere
changed in step with sunspot numbers until 1970".

"What's more, the most recent calculations by *Solanki's* team suggest
that the sunspot crash could lead to a cooling of the Earth's atmosphere
by 0.2 °C".

"In another study, *Solanki* has found an intriguing correlation between
the temperature of the Earth's atmosphere and the number of cosmic rays
striking it, with lower temperatures in periods of high numbers of
cosmic rays".

[New Scientist 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.
Fortunately, an indirect record of the sun's moods stretching back
thousands of years has been preserved on Earth in the concentrations of
rare isotopes locked into tree rings and ice cores. The story begins way
out beyond the orbit of Pluto, at the boundary of the sun's magnetic
field. While the sun is magnetically calm, its field extends around 12
billion kilometres into space, but the field puffs up to 15 billion
kilometres when the sun is active. Cosmic rays - the high-energy
particles from deep space that are constantly hurtling towards us - are
deflected by the field, so at active times far fewer of them reach the
Earth.
Cosmic correlation
The rays that do reach our planet leave traces in the form of carbon-14
and beryllium-10, isotopes that are only created when cosmic rays slam
into the Earth's atmosphere. Plants and trees then absorb carbon-14,
while beryllium-10 settles onto the polar ice sheets and becomes
incorporated into that year's ice layer. So by measuring the levels of
the isotopes in tree rings and polar ice cores, we can work out how many
cosmic rays were reaching Earth when the rings or ice layers were
formed, and so estimate how active the sun was at those times.
Sami Solanki and his team at the Max Planck Institute for Solar System
Research in Katlenburg-Lindau, Germany, have looked at the
concentrations of carbon-14 in wood and beryllium-10 in ice as far back
as back 11,000 years ago. The similarity of the fluctuations in both
isotopes convinced them that they were seeing effects due to the sun.
The peaks and slumps showed a recognisable pattern: "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."
Although another crash is likely, predicting the sun's activity with any
certainty is difficult because of the chaotic way in which the solar
magnetic field is generated. If anyone can do it, though, it's solar
physicist turned computer programmer Leif Svalgaard, from Stanford
University in California, who has been forecasting solar activity for
nearly three decades. In the 1970s, he pioneered the best forecasting
method yet devised, which uses the strength of the magnetic field at the
sun's poles to predict future levels of solar activity.
He too expects a crash. 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.
Hot link
So what does the sun's magnetic activity have to do with the climate on
Earth? To pin down the connection, Solanki and his colleagues compared
records of solar activity derived from tree rings with meteorological
records from 1856 to the present day. They found that the temperature of
the Earth's atmosphere changed in step with sunspot numbers until 1970.
This is the evidence that has done more than anything else to convince
climatologists to take the link seriously. What's more, the most recent
calculations by Solanki's team suggest that the sunspot crash could lead
to a cooling of the Earth's atmosphere by 0.2 °C. It might not sound
much, but this temperature reversal would be as big as the most
optimistic estimate of the results of restricting greenhouse-gas
emissions until 2050 in line with the Kyoto protocol.
There is still a big puzzle, though. Astronomers and climate scientists
have always struggled to understand exactly how solar activity could
influence the temperature on Earth. Whatever the variations in the sun's
magnetic activity, the total energy it emits changes by only 0.1 per
cent - too small a change to have any direct effect. As a result, the
sun's role in climate change is highly controversial. "People have been
arguing over this for years," says Reimer.
What other factor is at work? Important clues have emerged recently from
solar observatories, including the SOHO spacecraft operated by NASA and
the European Space Agency for the past 10 years. Although the change in
overall solar energy is small, measurements made by SOHO and other solar
observatories have revealed much greater variation in the levels of
ultraviolet radiation, which can peak at up to 100 times its minimum
level. "This means that there is scope for ultraviolet to have a much
larger effect on our atmosphere," says Haigh, who for the past decade
has been studying the impact of the sun's variability on climate.
According to computer models she has developed, ultraviolet radiation
heats the upper reaches of the Earth's atmosphere by energising atoms
and molecules there. This drives chemical reactions involving ozone and
other molecules, which can release still more heat. This heating changes
the temperature structure of the atmosphere at all altitudes, although
the details are unclear because of the sheer complexity of Haigh's
model. "By varying the amount of ultraviolet radiation, solar activity
changes the circulation of the whole atmosphere," she says. Change the
circulation, and you change the weather.
Haigh's work may help to explain one of the most puzzling aspects of the
Little Ice Age: "Europe was badly hit, but other parts of the world may
not really have noticed it," says Solanki. This might have been due to
the different distribution of land masses in the northern and southern
hemispheres. While Antarctica is surrounded by a wide belt of ocean, the
distribution of land and oceans in the northern hemisphere is much less
regular. This means that the interaction between the circulating
atmosphere and the ground is more complex in the northern hemisphere. It
gives rise to the North Atlantic Oscillation, an interplay of low and
high pressure that dictates the movement of storms across the continents
bordering the north Atlantic.
Haigh has found that at times of low solar activity the air pressure
over the North Pole is higher than normal and forces storms south,
funnelling colder weather to lower latitudes. What happens in the
southern hemisphere is less well known, but Haigh says she wouldn't be
surprised if the reaction here to changes in solar activity is
different.
Solar activity might also influence climate through its effect on cosmic
rays. In another study, Solanki has found an intriguing correlation
between the temperature of the Earth's atmosphere and the number of
cosmic rays striking it, with lower temperatures in periods of high
numbers of cosmic rays.
How could cosmic rays lead to cooler temperatures? Enter a theory
proposed by Henrik Svensmark and Eigil Friis-Christensen of the Danish
Meteorology Institute in Copenhagen almost a decade ago. They suggested
that cosmic rays create an electric charge in particles in our
atmosphere that then act as seeds for the formation of clouds at low
altitudes. A spell of low solar activity would mean more cosmic rays and
therefore more clouds and lower temperatures.
Svensmark and Friis-Christensen's idea is controversial, however (New
Scientist, 11 July 1998, p 45). Most climatologists accept that more low
clouds would reflect more radiation back into space, thus lowering
temperatures. But many dismiss Svensmark and Friis-Christensen's
evidence of a link between cosmic rays and cloud cover as coincidence
(see "Cloud cover"). Others want the theory investigated, if only to
rule it out. To this end, an international group of more than 50
scientists have proposed an experiment at the CERN particle physics
laboratory near Geneva, Switzerland, to begin in 2008.
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

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