Svensmark: "global warming stopped and a cooling is beginning" – "enjoy global warming while it lasts"

UPDATED: This opinion piece from Professor Henrik Svensmark was published September 9th in the Danish newspaper Jyllands-Posten. Originally the translation was from Google translation with some post translation cleanup of jumbled words or phrases by myself. Now as of Sept 12, the translation is by Nigel Calder.  Hat tip to Carsten Arnholm of Norway for bringing this to my attention and especially for translation facilitation by Ágúst H Bjarnason – Anthony

Catainia photosphere image August 31st, 2009 - click for larger image
Spotless Cueball: Catania observatory photosphere image August 31st, 2009 - click for larger image

While the sun sleeps

Translation approved by Henrik Svensmark

While the Sun sleeps

Henrik Svensmark, Professor, Technical University of Denmark, Copenhagen

“In fact global warming has stopped and a cooling is beginning. No climate model has predicted a cooling of the Earth – quite the contrary. And this means that the projections of future climate are unreliable,” writes Henrik Svensmark.

The star that keeps us alive has, over the last few years, been almost free of sunspots, which are the usual signs of the Sun’s magnetic activity. Last week [4 September 2009] the scientific team behind the satellite SOHO (Solar and Heliospheric Observatory) reported, “It is likely that the current year’s number of blank days will be the longest in about 100 years.” Everything indicates that the Sun is going into some kind of hibernation, and the obvious question is what significance that has for us on Earth.

If you ask the Intergovernmental Panel on Climate Change (IPCC) which represents the current consensus on climate change, the answer is a reassuring “nothing”. But history and recent research suggest that is probably completely wrong. Why? Let’s take a closer look.

Solar activity has always varied. Around the year 1000, we had a period of very high solar activity, which coincided with the Medieval Warm Period. It was a time when frosts in May were almost unknown – a matter of great importance for a good harvest. Vikings settled in Greenland and explored the coast of North America. On the whole it was a good time. For example, China’s population doubled in this period.

But after about 1300 solar activity declined and the world began to get colder. It was the beginning of the episode we now call the Little Ice Age. In this cold time, all the Viking settlements in Greenland disappeared. Sweden surprised Denmark by marching across the ice, and in London the Thames froze repeatedly. But more serious were the long periods of crop failures, which resulted in poorly nourished populations, reduced in Europe by about 30 per cent because of disease and hunger.

"The March across the Belts was a campaign between January 30 and February 8, 1658 during the Northern Wars where Swedish king Karl X Gustav led the Swedish army from Jutland across the ice of the Little Belt and the Great Belt to reach Zealand (Danish: Sjælland). The risky but vastly successful crossing was a crushing blow to Denmark, and led to the Treaty of Roskilde later that year...." - Click for larger image.

It’s important to realise that the Little Ice Age was a global event. It ended in the late 19th Century and was followed by increasing solar activity. Over the past 50 years solar activity has been at its highest since the medieval warmth of 1000 years ago. But now it appears that the Sun has changed again, and is returning towards what solar scientists call a “grand minimum” such as we saw in the Little Ice Age.

The match between solar activity and climate through the ages is sometimes explained away as coincidence. Yet it turns out that, almost no matter when you look and not just in the last 1000 years, there is a link. Solar activity has repeatedly fluctuated between high and low during the past 10,000 years. In fact the Sun spent about 17 per cent of those 10,000 years in a sleeping mode, with a cooling Earth the result.

You may wonder why the international climate panel IPCC does not believe that the Sun’s changing activity affects the climate. The reason is that it considers only changes in solar radiation. That would be the simplest way for the Sun to change the climate – a bit like turning up and down the brightness of a light bulb.

Satellite measurements have shown that the variations of solar radiation are too small to explain climate change. But the panel has closed its eyes to another, much more powerful way for the Sun to affect Earth’s climate. In 1996 we discovered a surprising influence of the Sun – its impact on Earth’s cloud cover. High-energy accelerated particles coming from exploded stars, the cosmic rays, help to form clouds.

When the Sun is active, its magnetic field is better at shielding us against the cosmic rays coming from outer space, before they reach our planet. By regulating the Earth’s cloud cover, the Sun can turn the temperature up and down. High solar activity means fewer clouds and and a warmer world. Low solar activity and poorer shielding against cosmic rays result in increased cloud cover and hence a cooling. As the Sun’s magnetism doubled in strength during the 20th century, this natural mechanism may be responsible for a large part of global warming seen then.

That also explains why most climate scientists try to ignore this possibility. It does not favour their idea that the 20th century temperature rise was mainly due to human emissions of CO2. If the Sun provoked a significant part of warming in the 20th Century, then the contribution by CO2 must necessarily be smaller.

Ever since we put forward our theory in 1996, it has been subjected to very sharp criticism, which is normal in science.

First it was said that a link between clouds and solar activity could not be correct, because no physical mechanism was known. But in 2006, after many years of work, we completed experiments at DTU Space that demonstrated the existence of a physical mechanism. The cosmic rays help to form aerosols, which are the seeds for cloud formation.

Then came the criticism that the mechanism we found in the laboratory could not work in the real atmosphere, and therefore had no practical significance. We have just rejected that criticism emphatically.

It turns out that the Sun itself performs what might be called natural experiments. Giant solar eruptions can cause the cosmic ray intensity on earth to dive suddenly over a few days. In the days following an eruption, cloud cover can fall by about 4 per cent. And the amount of liquid water in cloud droplets is reduced by almost 7 per cent. Here is a very large effect – indeed so great that in popular terms the Earth’s clouds originate in space.

So we have watched the Sun’s magnetic activity with increasing concern, since it began to wane in the mid-1990s.

That the Sun might now fall asleep in a deep minimum was suggested by solar scientists at a meeting in Kiruna in Sweden two years ago. So when Nigel Calder and I updated our book The Chilling Stars, we wrote a little provocatively that “we are advising our friends to enjoy global warming while it lasts.”

In fact global warming has stopped and a cooling is beginning. Mojib Latif from the University of Kiel argued at the recent UN World Climate Conference in Geneva that the cooling may continue through the next 10 to 20 years. His explanation was a natural change in the North Atlantic circulation, not in solar activity. But no matter how you interpret them, natural variations in climate are making a comeback.

The outcome may be that the Sun itself will demonstrate its importance for climate and so challenge the theories of global warming. No climate model has predicted a cooling of the Earth – quite the contrary. And this means that the projections of future climate are unreliable. A forecast saying it may be either warmer or colder for 50 years is not very useful, and science is not yet able to predict solar activity.

So in many ways we stand at a crossroads. The near future will be extremely interesting. I think it is important to accept that Nature pays no heed to what we humans think about it. Will the greenhouse theory survive a significant cooling of the Earth? Not in its current dominant form. Unfortunately, tomorrow’s climate challenges will be quite different from the greenhouse theory’s predictions. Perhaps it will become fashionable again to investigate the Sun’s impact on our climate.

Professor Henrik Svensmark is director of the Center for Sun-Climate Research at DTU Space. His book The Chilling Stars has also been published in Danish as Klima og Kosmos Gads Forlag, DK ISBN 9788712043508)


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Phil's Dad
September 11, 2009 12:46 pm

tallbloke (12:20:08) :
Works for me

Ron de Haan
September 11, 2009 1:07 pm

Juraj V. (11:53:49) :
To refute distant MWP is an old trick, but to refute also relatively recent and well recorded LIA is plain laughable”.
Juaj V.,
I like what you are saying but we are missing out on the volcanic wild card.
This too played quite a role in several extreme events that took place during the LIA.

Gene Nemetz
September 11, 2009 1:08 pm

Phil’s Dad (08:59:07) :
I can see you are versed. Are you becoming the Senator Inhofe of England? He has made so good presentations to the Senate.

Barry Foster
September 11, 2009 1:12 pm

Dolormin. I’m an engineer, not a scientist, so I cannot work with the 95% error bars that scientists allow themselves http://rankexploits.com/musings/2008/ols-with-pumped-up-error-bars-is-crude-the-ipcc-2-ccentury-still-falsified/. If I did, I’d be covering myself (very well, admittedly) if someone died as a result of something I designed or constructed. Surely it’s better to say, ‘We don’t have much of a clue, really”? I live in England. Like I said before, we have the infamous Met Office. Their predictions really are dire – and wrong most of the time. Let me tell you why. They CANNOT predict what the weather will be over my city with any certainty. They know this, and I know this. So they predict it for a region around my city BUT cover themselves by saying that “Some areas may have rain” Do you see what they did there? They’re covered! If I get rain, but my sister 20 miles away doesn’t then they’re correct. If it’s the reverse, they’re correct. If we both get it, they’re still correct! Based on this pathetic level of prediction they award themselves with an 80%+ ‘predicted-correct’ tag. Like I said, I cannot afford such error bars. I couldn’t design a walkway and say ‘There’s a good chance that it won’t hold 100 people all at once, but there’s a chance it will’! I would have to say a maximum number of people. As I said, I didn’t realise that science worked with wildly varying degrees of UNcertainty. I’ll tell you something else. As an atheist I used to look down on the religious because they believe something for which there is no evidence. And here was I, a man who bases his working life on science, aloof in the knowledge that theories would be tested and conclusions drawn. When I look at the utter debacle of what passes for climate science I am appalled. They are dragging down all the other sciences with them – and I’ve read that many geologists are furious with the claims made by climatologists. They’ve seen rapid warming and cooling in rocks – completely natural. Here in England we have the Central England Temperature (CET). From 1696 to 1732 the temperature in England rose 2.2 degrees C, was wholly natural in origin, and was over twice the warming we are experiencing now. I can no longer look down on the religious. I tell you this Dolormin, if we do get a period of 20 years of cooling, then science itself will suffer. People already remember the scares of the past, like a coming ice age, acid rain, the millenium bug, bird flu, world starvation (by now), ozone depletion, and swine flu. They will start to laugh at scientists and their error bars. What good is a prediction if you build-in a huge ‘get-out’? For how much longer do you think the media will be the messengers for crackpot theories on ‘icecaps melting’? Not for long, my friend, not for long.

dorlomin
September 11, 2009 1:18 pm

Smokey (12:10:57) :
dolormin:
“So you think you are not an echo chamber?”
That’s exactly right. WUWT is not an echo chamber, it is more a peer review site than anything. Ideas are argued until the truth is sorted out when possible. Tamino, RC, climateprogress, etc., are echo chambers.
—————————————————
Please dont be so modest. You are more than that. You are the guardians of science in an age of religous fervour. An uncensorsed beacon of light saving science from the “scientists”. Give yourselves (yet) another pat on the back!

dorlomin
September 11, 2009 1:19 pm

Mr. Alex (11:52:19) :
dorlomin (11:11:14) :
“Try the lifecycle of stars, they get hotter as they get older.”
So you are implying that the much higher CO₂ levels in the distant past kept the Earth warm enough to support diversifiation and explosion of life & prevented the Earth from perhaps freezing over, which would otherwise have happened due to the cooler sun which could not provide enough energy to prevent snowball Earth from occurring?
Try this; CO₂, unlike the sun, does not radiate energy which can heat the Earth, sorry “mate”.
—————————————-
So why did it not freeze? 🙂

Gene Nemetz
September 11, 2009 1:20 pm

Mike McMillan (03:34:03) : The CO2 chart climb is as steady as you get, but the global temperature it’s supposed to be driving seem pretty oblivious to it….About the only things keeping pace with CO2 are the GISS adjustments.
Despite the hackneyed response to my earlier comment on this quote I still think it was nicely put by Mike McMillan.
i.e. :
About the only things keeping pace with CO2 are the GISS adjustments.
(bolds by me 😉)

Ron de Haan
September 11, 2009 1:25 pm

Talking about the Volcanic Wild Card:
http://volcanism.wordpress.com/2009/09/11/shiveluch-erupts/
Shiveluch erupts 11 September 2009
Posted by admin in Kamchatka, Russia, Shiveluch, activity reports, eruptions.
Tags: Kamchatka, Russia, Shiveluch, volcanic activity reports, volcanic eruptions
trackback
Reports from Russia indicate that a large eruption of Shiveluch began yesterday. A bulletin from the Kamchatka Volcanoes Emergency Response Team (KVERT), issued at 22:35 UTC on 10 September warns that ‘Ash explosions > 10 km (>32,800 ft) ASL from the volcano could affect international and low-flying aircraft’. According to the bulletin, ’strong explosions’ occurred between around 14:19 and 14:55 UTC on 10 September, with seismic data indicating ash plumes reaching 15000 metres above sea level; if ash plumes are indeed reaching 10-15 km altitude, then this is a sizeable event. The bulletin reports that according to seismic data ‘10 volcanic events (ash explosions and hot avalanches or pyroclastic flows) occurred at the lava dome from 16:33 till 20:25 UTC on September 10′. Whether the activity is still continuing is not clear, and there are no visual or satellite images of this event because of cloud cover.
End of message.

Jack Simmons
September 11, 2009 1:36 pm

Robert E. Phelan (05:07:08) :

I have no way of knowing whether Dr. Svensmark is correct about cosmic rays and clouds but he is definitely not correct about poor harvests causing a 30% decline in Europe’s population during the Little Ice Age. That phenomenon was caused by something called the Black Death, a bubonic plague spread by flea carrying rats that started in China, spread across Asia and reached Constantinople about 1346. By 1347 it had hopped a ship to Genoa and by 1351 nearly half the population of Europe was dead. European population did not reach it’s pre-plague level until just about 1500, at which point it was about just slightly larger than the population of Europe at the height of the Roman Empire.

The two are not necessarily mutually exclusive. Poor diets lead to weak immune systems as well as poor hygiene. Just read some of the accounts from POW camps run by the Japanese, Russians, and Nazis.
You are correct in bringing up the plague contributing to the die offs in Europe at the time.

jlc
September 11, 2009 1:42 pm

“This very, very close to an ad hom. quite uncharacteristically for Leif”
Not at all uncharacteristic for the smug, sanctimonious and omniscient Lief.

Barry Foster
September 11, 2009 1:49 pm

Dolormin. More divergence between models and reality – this time on ocean temperatures. http://icecap.us/images/uploads/argodata.jpg

September 11, 2009 1:50 pm

Johnny Honda (09:55:37) :
The more I read on Tamino’s blog “feeble mind” (sorry for more publicity for this), the more I question his physical knowledge:
“Global temperature responds to changes in the energy flow of earth’s climate system. When more energy flows through the system the planet heats up; with less energy flow the planet cools down
Changes in the energy flow constitute climate forcings. We know of many, including greenhouse gases, solar changes, ozone, snow albedo, land use, aerosols (both from volcanoes and from industrial processes), etc.
By adding greenhouse gases to the atmosphere more energy flows through the system?? The energy flow through the system is not changed by greenhouse gases. There is a diagram on Wikipedia with the energy flows through the atmosphere, there everybody can see, that the greenhouse effect doesn’t change the energy flow at all.

Actually it’s your physical knowledge that’s in doubt, in the absence of greenhouse gases the earth would be ~33ºC cooler, which is a significant drop in ‘energy flow through the system’.

Jack Simmons
September 11, 2009 2:02 pm

Stefan (05:29:17) :

What the greens fail to notice however, is that authoritarian “social order” can serve any number of priorities. It can serve empire building, it can serve warmongering, it can serve any group goal, really. There is nothing inherently green about being authoritarian. And groups can also organise in far more interesting ways than simply becoming authoritarian top-down power structures.
I think the greens that follow the authoritarian model are in for a nasty shock.

North Korea is an excellent example. Not only have all businesses and consumers been brought under control, there are very few green house gases being generated. People live very simple lives there, in harmony with nature. As there is very little food, people must scour the hills looking for anything edible. Very few cars, very little electricity, no wasted resources on consumer goods. Even the military must put up with very little fuel to run jet fighters and tanks.
http://tonto.eia.doe.gov/country/country_energy_data.cfm?fips=KN
Now contrast this worker’s and environmentalist’s paradise with those profligate cousins down south:
http://tonto.eia.doe.gov/country/country_energy_data.cfm?fips=KS

RR Kampen
September 11, 2009 2:07 pm

The Diatribe Guy (09:53:44) :
“But these kinds of analyses [fitting a sine curve, RR] are just too simple for academia to take them seriously.”
In fact, for a finite number of data it is possible to fit a polynomial curve of degree [number of data] +1 that fits absolutely exactly.
Obviously projections of this model will show true runaway warming (if you chose the number of data points to be uneven).
Using powers of sine and/or cosine you can also make an exact fit. They ‘prove’ that in the long run there can be no climate change, just a repetition of waves or wave-groups – unless you take an infinite number of terms in the model (which can never be calculated, then).
I’m guessing now you can understand why academia wouldn’t want to use such simple models.
They contain no physics and therefore they cannot contain any predictive value. They contain no knowledge.

rbateman
September 11, 2009 2:07 pm

Leif Svalgaard (11:50:13) :
There is nothing flowery about looking at a section of data and asking yourself “where have I seen this slope before?”, and it is not cherry picking until one proclaims it is “This” and cannot be anything else.
The range of time/space is deliberate.
You have given me tasks just like this, but you gave it unbiased and let me draw my own conclusions.
So I am returning the favor…and not attempting to pre-color it with what I see.

September 11, 2009 2:10 pm

rbateman (14:07:38) :
“where have I seen this slope before?”,
Assuming that you
and it is not cherry picking until one proclaims it is “This” and cannot be anything else.
The range of time/space is deliberate.
You have given me tasks just like this, but you gave it unbiased and let me draw my own conclusions.
So I am returning the favor…and not attempting to pre-color it with what I see.

September 11, 2009 2:13 pm

rbateman (14:07:38) :
where have I seen this slope before?
Assuming that you are referring to cosmic rays, I have seen these curves many times before. I don’t see anything that is not what I would expect, so am still a bit lost.

E.M.Smith
Editor
September 11, 2009 2:26 pm

Flanagan (00:36:42) : A very mysterious mechanism indeed. And still not supported by any observation. Moreover, how is it the sun is “fading” since the 90ies and all we got is a warming?
Hooo HaaaHoha hik… What a hoot! And you really believe this stuff?
Flanagan, whatever you are smoking, I want some! (But only on Fridays, I need to be “straight” by the time markets open Monday…)
So, you expect a few giga-tons (tera-tons? peta-tons?) of matter to have an instant response to delta energy generation? Let me loan you a tiny bit of clue: It can take hundreds of years for LIGHT to move up a few layers in the sun. A decade or so is darned near “instant” in things that big and with that scale.
And oh, BTW, your “warming” is false as well. The books are cooked. I know, I’ve read the recipe and documented just exactly how the books are cooked. GIStemp measures ASPHALT growth at AIRPORTS as they move from Siberia to Brazil. Nothing more. (Well, maybe a little bit more, there is that one line of code that warms 1/100 of all records by 1/10C due to bad programming style – I guess it does measure “Bad Hacking” too…)
2009 is not going to be a cold year, far from that.
Too late. It already is. Hundreds of children dead in Peru from early onset snow. Crops ripening slowly in Canada and late planting from persistent snows. Argentina talking about a complete embargo of wheat exports due to cold induced crop failure (they are one of the few major exporters in the world in normal years…) Exceptional skiing started in New Zealand and Australia, the list goes on.
But no problem, you want to drink that cool-aid, fine with me. Just don’t expect the rest of us to join in. We know what’s in it, and it isn’t pretty:
http://chiefio.wordpress.com/gistemp/
August and July were globally pretty hot and September seems to be setting a new record
http://chiefio.wordpress.com/2009/09/08/gistemp-islands-in-the-sun/
Can explain why you think it is hotter “globally”. Hint: It has to do with putting a lot of thermometers on the tarmac on tropical islands during the growth of the Jet Age then using them to say that the surrounding water is the same temperature. Yes, it really does that. 2 islands ‘warm’ and area teh size of the entire U.S.A. No, boxing, gridding, anomalies et.al. can not save you from this – THIS is from the post anomaly boxing gridding step. It’s over.
Now here is a tiny little experiment for you. Go to the Marshall Islands (as in the picture in the link). Lay on the tarmac at 2 pm for an hour. Then go jump in the ocean. Which is cooler?
Don’t think this is a reasonable thing? Think the thermometer will be far far away from the tarmac? Look at the picture. There isn’t any far far away from the tarmac at that airport!

crosspatch
September 11, 2009 2:27 pm

he to-be-prime-minister Yukio Hatoyama announced at a recent press conference that he wanted to aim at 25% curbing of CO2 emission by 2020 with respect to the level in 1990. This is quite embarassing to me

I would find more embarrassing the statements of his wife that she had been abducted by aliens, take to the planet Venus and that it was “very green there”.

September 11, 2009 2:33 pm

The newest CO2 Report by Viscount Monckton just came out: click
It covers some of what’s discussed in this thread, and has some nice graphs.

Stephen Wilde
September 11, 2009 2:36 pm

Phil’s Dad (10:40:48)
Thanks for the clarification. I see your position more clearly now and don’t disagree with what you say.
However, please reduce interference instead of constantly increasing it at public expense. We really do not want all the supervision and regulation being cack handedly foisted on us.
A few hundred British officials effectively managed the Indian subcontinent for 300 years with the consent and help of most of the locals who preferred our rule of law to the previous tribal warfare.
Why do we need so many of you chaps these days with all of you with little to do except invent new obstacles for everyone else ?
Sorry for going too much off topic but if we have a politician here he needs to be told.

E.M.Smith
Editor
September 11, 2009 2:43 pm

dorlomin (01:13:20) :
“Barry Foster (01:03:31) :What the Warmists forget (whether intentionally or not) is that this flatline of temperature (or even cooling) was not predicted by models. ”
Curious, this is not what I have been told, I have always understood that natural variability can cause temporary decreases in temperature. I guess we have different sources. Perhaps you could produce a quote that states what you have said this clearly?

Different subject to the sentences…
What the AWG Believers say is it is possible to have temporary cooling. What the MODELS predict (pardon, project, like projectile v..) is rising temps. So the MODELS are bunk since they cannot predict (or project) a cooling trend. Oh, and they are fed on broken temperature series from GIStemp et.al. G. in G. out …

E.M.Smith
Editor
September 11, 2009 2:58 pm

Robert E. Phelan (05:07:08) : I have no way of knowing whether Dr. Svensmark is correct about cosmic rays and clouds but he is definitely not correct about poor harvests causing a 30% decline in Europe’s population during the Little Ice Age. That phenomenon was caused by something called the Black Death, a bubonic plague
But that plague spread, in part, due to the poor nutritional status of the population. Plague did not just evolve overnight as a new species… The outbreak of plague had causes too…

Henrik Svensmark
September 11, 2009 3:01 pm

Dear Anthony,
Nigel Calder has been so kind to translate my article. It is a good translation.
Best wishes,
Henrik
Published 9 September 2009 in Jyllands-Posten, Denmark’s best-selling newspaper.
Translation approved by Henrik Svensmark
While the Sun sleeps
Henrik Svensmark, Professor, Technical University of Denmark, Copenhagen
“In fact global warming has stopped and a cooling is beginning. No climate model has predicted a cooling of the Earth – quite the contrary. And this means that the projections of future climate are unreliable,” writes Henrik Svensmark.
The star that keeps us alive has, over the last few years, been almost free of sunspots, which are the usual signs of the Sun’s magnetic activity. Last week [4 September 2009] the scientific team behind the satellite SOHO (Solar and Heliospheric Observatory) reported, “It is likely that the current year’s number of blank days will be the longest in about 100 years.” Everything indicates that the Sun is going into some kind of hibernation, and the obvious question is what significance that has for us on Earth.
If you ask the Intergovernmental Panel on Climate Change (IPCC) which represents the current consensus on climate change, the answer is a reassuring “nothing”. But history and recent research suggest that is probably completely wrong. Why? Let’s take a closer look.
Solar activity has always varied. Around the year 1000, we had a period of very high solar activity, which coincided with the Medieval Warm Period. It was a time when frosts in May were almost unknown – a matter of great importance for a good harvest. Vikings settled in Greenland and explored the coast of North America. On the whole it was a good time. For example, China’s population doubled in this period.
But after about 1300 solar activity declined and the world began to get colder. It was the beginning of the episode we now call the Little Ice Age. In this cold time, all the Viking settlements in Greenland disappeared. Sweden surprised Denmark by marching across the ice, and in London the Thames froze repeatedly. But more serious were the long periods of crop failures, which resulted in poorly nourished populations, reduced in Europe by about 30 per cent because of disease and hunger.
It’s important to realise that the Little Ice Age was a global event. It ended in the late 19th Century and was followed by increasing solar activity. Over the past 50 years solar activity has been at its highest since the medieval warmth of 1000 years ago. But now it appears that the Sun has changed again, and is returning towards what solar scientists call a “grand minimum” such as we saw in the Little Ice Age.
The match between solar activity and climate through the ages is sometimes explained away as coincidence. Yet it turns out that, almost no matter when you look and not just in the last 1000 years, there is a link. Solar activity has repeatedly fluctuated between high and low during the past 10,000 years. In fact the Sun spent about 17 per cent of those 10,000 years in a sleeping mode, with a cooling Earth the result.
You may wonder why the international climate panel IPCC does not believe that the Sun’s changing activity affects the climate. The reason is that it considers only changes in solar radiation. That would be the simplest way for the Sun to change the climate – a bit like turning up and down the brightness of a light bulb.
Satellite measurements have shown that the variations of solar radiation are too small to explain climate change. But the panel has closed its eyes to another, much more powerful way for the Sun to affect Earth’s climate. In 1996 we discovered a surprising influence of the Sun – its impact on Earth’s cloud cover. High-energy accelerated particles coming from exploded stars, the cosmic rays, help to form clouds.
When the Sun is active, its magnetic field is better at shielding us against the cosmic rays coming from outer space, before they reach our planet. By regulating the Earth’s cloud cover, the Sun can turn the temperature up and down. High solar activity means fewer clouds and and a warmer world. Low solar activity and poorer shielding against cosmic rays result in increased cloud cover and hence a cooling. As the Sun’s magnetism doubled in strength during the 20th century, this natural mechanism may be responsible for a large part of global warming seen then.
That also explains why most climate scientists try to ignore this possibility. It does not favour their idea that the 20th century temperature rise was mainly due to human emissions of CO2. If the Sun provoked a significant part of warming in the 20th Century, then the contribution by CO2 must necessarily be smaller.
Ever since we put forward our theory in 1996, it has been subjected to very sharp criticism, which is normal in science.
First it was said that a link between clouds and solar activity could not be correct, because no physical mechanism was known. But in 2006, after many years of work, we completed experiments at DTU Space that demonstrated the existence of a physical mechanism. The cosmic rays help to form aerosols, which are the seeds for cloud formation.
Then came the criticism that the mechanism we found in the laboratory could not work in the real atmosphere, and therefore had no practical significance. We have just rejected that criticism emphatically.
It turns out that the Sun itself performs what might be called natural experiments. Giant solar eruptions can cause the cosmic ray intensity on earth to dive suddenly over a few days. In the days following an eruption, cloud cover can fall by about 4 per cent. And the amount of liquid water in cloud droplets is reduced by almost 7 per cent. Here is a very large effect – indeed so great that in popular terms the Earth’s clouds originate in space.
So we have watched the Sun’s magnetic activity with increasing concern, since it began to wane in the mid-1990s.
That the Sun might now fall asleep in a deep minimum was suggested by solar scientists at a meeting in Kiruna in Sweden two years ago. So when Nigel Calder and I updated our book The Chilling Stars, we wrote a little provocatively that “we are advising our friends to enjoy global warming while it lasts.”
In fact global warming has stopped and a cooling is beginning. Mojib Latif from the University of Kiel argued at the recent UN World Climate Conference in Geneva that the cooling may continue through the next 10 to 20 years. His explanation was a natural change in the North Atlantic circulation, not in solar activity. But no matter how you interpret them, natural variations in climate are making a comeback.
The outcome may be that the Sun itself will demonstrate its importance for climate and so challenge the theories of global warming. No climate model has predicted a cooling of the Earth – quite the contrary. And this means that the projections of future climate are unreliable. A forecast saying it may be either warmer or colder for 50 years is not very useful, and science is not yet able to predict solar activity.
So in many ways we stand at a crossroads. The near future will be extremely interesting. I think it is important to accept that Nature pays no heed to what we humans think about it. Will the greenhouse theory survive a significant cooling of the Earth? Not in its current dominant form. Unfortunately, tomorrow’s climate challenges will be quite different from the greenhouse theory’s predictions. Perhaps it will become fashionable again to investigate the Sun’s impact on our climate.
Professor Henrik Svensmark is director of the Center for Sun-Climate Research at DTU Space. His book The Chilling Stars has also been published in Danish as Klima og Kosmos Gads Forlag, DK ISBN 9788712043508)

Mike Abbott
September 11, 2009 3:02 pm

Scott A. Mandia (07:39:41) :
I would be very careful if you intend to tap Tamino’s bees nest. You will likely be coming to a gun fight armed with a knife.

Lucia from the Blackboard recently came to Tamino’s bees nest and blasted him with a bazooka. I’m referring to her apparent proof that one of his analyses violated the 2nd law of thermodynamics. She was permanently banned from his board.

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