In a nutshell, with a −1.6%per decade change in cloud cover during 1954–2005, it becomes a climate forcing. While China is not the world, it bears consideration.
The Hockey Schtick reports:
New paper finds significant, natural decrease in cloudiness over past 50 years
A paper published last week finds that cloud cover over China significantly decreased during the period 1954-2005. This finding is in direct contradiction to the theory of man-made global warming which presumes that warming allegedly from CO2 ‘should’ cause an increase in water vapor and cloudiness. The authors also find the decrease in cloud cover was not related to man-made aerosols, and thus was likely a natural phenomenon, potentially a result of increased solar activity via the Svensmark theory or other mechanisms. As climatologist Dr. Roy Spencer has pointed out his book,
“The most obvious way for warming to be caused naturally is for small, natural fluctuations in the circulation patterns of the atmosphere and ocean to result in a 1% or 2% decrease in global cloud cover. Clouds are the Earth’s sunshade, and if cloud cover changes for any reason, you have global warming — or global cooling.”
Ann. Geophys., 30, 573-582, 2012
www.ann-geophys.net/30/573/2012/
doi:10.5194/angeo-30-573-2012
X. Xia
LAGEO, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
================================================================
Abstract:
An updated analysis of cloud cover during 1954–2005 in China was performed using homogeneous cloud cover data from 314 stations. Long-term changes in frequencies of different cloud cover categories and their contributions to long-term changes in cloud cover were assessed. Furthermore, aerosol effects on cloud cover trends were discussed based on comparison of cloud cover trends in polluted and mildly polluted regions. Frequencies of clear sky (cloud cover <20%) and overcast days (cloud cover >80%) were observed to increase by ~2.2 days and decrease by ~3.3 days per decade, respectively, which accounts for ~80% of cloud cover reduction. Larger decreasing trends in cloud cover due to larger increase in clear sky frequency and larger decreases in overcast frequency were observed at stations with lower aerosol optical depth. There is no significant difference in trends regarding cloud cover, clear sky frequency, and overcast frequency between mountain and plain stations. These results are inconsistent with our expectation that larger decreasing trends in cloud cover should have been observed in regions with higher aerosol loading where more aerosols could lead to stronger obscuring effect on ground observation of cloud cover and stronger radiative effect as compared with the mildly polluted regions. Aerosol effect on decreasing cloud cover in China appear not to be supported by this analysis and therefore, further study on this issue is required.
Summary:
A homogeneous cloud cover dataset in China was used to study long-term changes in cloud cover and frequencies of cloud cover categories. A simple yet effective statistical method was applied to study quantitative contributions of graded cloud cover frequency to the overall trend in cloud cover. The relationship between AOD and cloud cover trend was analyzed to discuss aerosol effects on decadal trend of cloud cover. Major conclusions follow.
Significant decline in cloud cover with trend of −1.6%per decade during 1954–2005 was derived. Occurrences of clear sky (cloud cover <20 %) and overcast days (>80 %) were observed to increase and decline by 2.2 days per decade and 3.3 days per decade, respectively. Approximately 80% of overall trend of cloud cover is attributable to an increase in clear-sky days and a decline in overcast days.
Larger decreasing cloud-amount trends have been observed due to larger increasing clear sky frequency and larger decreasing overcast frequency at stations with lower AOD.
There is not significant difference among trends of cloud cover, clear sky frequency, and overcast sky frequency between mountain and plain stations. These analyses do not
support the speculation that the decreasing trend of cloud cover in regions with higher AOD should be larger than that in mildly polluted regions due to stronger aerosol obscuring effect on ground observation of cloud cover and stronger radiative effect in polluted regions. This suggests that causes for significant decreasing trend in cloud cover in China require further study.
Link to the full paper is here: http://www.ann-geophys.net/30/573/2012/angeo-30-573-2012.pdf
Leif says…
Of course I have, but that is probably an instrumental fluke as ACRIM TSI was down again in 2008. To reiterate: “there is no observational evidence for any persistent trend in TSI at mimina.
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How do you know it’s a fluke other than the fact that TSI went down at the next Solar Minimum? How can you explain Fall et. al 2011’s finding that at the best sited weather stations there is no diurnal trend, while temperature anomalies climbed? How can you account for the fact that Clouds are decreasing? How can you account for the fact that more TSI is reaching Earth’s Surface?
There are a lot of variables that point to the ACRIM composite being more accurate than the PMOD composite.
Leif says… No, I have solar data going all the way back three hundred years showing no convincing solar connection with climate.
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That’s interesting, considering the sun is the reason why the temperature rises during the day, and it is the energy supply of everything on Earth, so I would assume it would have something to do with the climate of Earth.
vukcevic says:
April 5, 2012 at 11:38 am
Sparks says:
April 5, 2012 at 11:14 am
………….
“Something like this
That word is BANNED on the WUWT don’t you know?”
vukcevic I suppose that forbidden word has it’s roll to play too, I was studying the mass vs Planetary positioning on sun spot number, the math at this stage adds up, It’s not a million miles away tho. We have to find out these things for ourselves I guess, This is why I never worry about how dumb my questions appear to be. I’m actually took a bit more seriously outside of the blogosphere. 🙂
vukcevic says:
April 5, 2012 at 11:38 am
I suppose that forbidden word has it’s roll to play too…
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You might like to look at the discussion of Dr. Nicola Scafetta’s work http://wattsupwiththat.com/tag/nicola-scafetta/
Snowlover:
“How do you know it’s a fluke other than the fact that TSI went down at the next Solar Minimum?”
Are you suggesting you can determine a “persistent” trend from one cycle?
“How can you account for the fact that Clouds are decreasing?”
How did you make the leap to any global cloud cover trend being a “fact”?
“How can you account for the fact that more TSI is reaching Earth’s Surface?”
How did the non-settled science suddenly become so certain?
Would you agree that the best way (for laypeople) to get at least some understanding of a scientific subject is to review a broad range of studies on that subject?
If so, here is one web page that has a paper list on cloud cover trends.
http://agwobserver.wordpress.com/2009/09/10/papers-on-global-cloud-cover-trends/
(I often search for papers on the given subjects and suggest them to the blog owner there – with no preference for conclusions of course – so that the lists keep growing. It’s a fantastic resource)
According to William Gray, PhD, Professor Emeritus of Atmospheric Sciences, CSU:
“GCMs assume that an increase in atmospheric CO2 will cause weak global warming and an
increase in global precipitation that will lead to a large increase in upper-level water vapor
and cloudiness. They simulate that this increase in water vapor and cloudiness will block
large amounts of infrared radiation emitted to space. New observations by satellite and
reanalysis data, however, do not support these GCM assumptions. The global warming that
has occurred since the mid-1970s has been associated with a modest decrease of global
upper tropospheric water vapor and an increase of Outgoing Longwave Radiation (OLR).
These measurements contradict model predictions.”
http://heartland.org/sites/all/modules/custom/heartland_migration/files/pdfs/24891.pdf
Leif:
Could change in solar activity account for Mars warming 4 times faster than Earth over the past 20 years?
http://hockeyschtick.blogspot.com/2010/05/whoopsmars-has-warmed-4-times-more-than.html
Or warming on Jupiter, Pluto, Neptune, Triton, etc.?
Hockey Schtick,
Regarding warming of the solar system, a 2001 study of Uranus posited that temperature had decreased on the planet from 1983 to 1998, just when the Earth was warming:
http://www.boulder.swri.edu/~layoung/eprint/ur149/Young2001Uranus.pdf
If you argue that Uranus has characteristics peculiar to it that may account for the temperature change, would that not also apply to the other planets? Or perhaps the sun is selective about which planets it will warm?
It is curious that while discussion rages about the quality of Earth’s climate monitoring system with its milions of temperature measurements from various sources, you imply some kind of certainty about the temperature trends of other planets, for which the data is many orders of magnitude more sparse – some studies relying on less than ten data points.
It also occurs to me that the people expressing the most certainty about AGW and related science are the critics. What’s your confidence interval on Mars warming? You base your understanding on an article at the website of ‘The Search for Extraterrestrial Intelligence’? Hmmmm.
barry says:
April 5, 2012 at 8:29 pm
barry don’t be an ass.
Studies of climate changes on other planets/moons almost universally conclude seasonal variation is the cause, rather than solar variation.
Mars
Neptune
Triton
Jupiter
Uranus
I know of only one paper that very tentatively attempts to link solar variation with extra-terrestrial climate, but it’s not a very good one. Still, for some kind of balance.
Neptune
Basically what I have suggested is in line with procedures used In detecting extrasolar planets orbiting stars. Anyone who believes that planets do not have an effect on the star they orbit are missing out on a lot of progress made recently in astronomy. At the moment I do think that the solar cycle is caused by the outer planets orbiting the sun, I think the math is there, I think the suns variability does indeed have an effect on the earths temperature. And more importantly I think that it would be a useful tool for meteorologists to understand this process and tie this Solar cycle down.
Even the fact that the term ‘solar cycle’ should be a clue to it’s mathematical nature, The heliocentric configuration of the outer planets are causing the solar cycle, when the solar cycle is high over successive decades this produces overall a higher energy budget reaching the inner planets. And when the solar cycle is lower over successive decades it produces a lower overall energy budget reaching the inner planets. the interesting thing about the outer planets is that we can very accurately predict their future positions and therefor will be able to predict future heliocentric configuration and it’s effect on the sun. it means the solar cycle can be predicted with incredible accuracy decades into the future. wouldn’t this be important?
Some so-called scientists need to put down that latest book they’re promoting and do some work.
Have a happy Easter!
Happy easter, Sparks.
As a purely mathematic exercise, the ‘harmonics’ of orbital patterns throughout the solar system offer so much variety that there will probably be more than one set of frequencies that fit with the solar cycle/s. How would you distinguish the *true* frequencies from other candidates?
Barry,
Your Mars link is broken, but is the same paper referred to in my post which found “rise in the Martian global temperature over the past 20 years. The rise, less than 2° for both surface and air temperature, is still significant from a geologic perspective” This is a non-seasonal change
The most recent of the two Neptune articles suggests a non-seasonal change in solar activity is responsible for warming
The Triton article states global warming has occurred since 1989 and that observations are the opposite of what would be expected for a seasonal change.
The Jupiter link notes climate change with no mention of seasonal influence.
In sum, you have done a great job disproving your claim, “Studies of climate changes on other planets/moons almost universally conclude seasonal variation is the cause, rather than solar variation.”
barry says:
April 6, 2012 at 11:55 am
“As a purely [mathematical] exercise, the ‘harmonics’ of orbital patterns throughout the solar system offer so much variety”
barry, This is called eccentricity! where The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle. It is also a measurable mathematical property. I wouldn’t go down the road of statistically Analysing planetary orbital deviations.(and it is not what I was suggesting)
“…that there will probably be more than one set of frequencies that fit with the solar cycle/s. How would you distinguish the *true* frequencies from other candidates?”
I would begin by observing the heliocentric configuration of the outer planetary orbital mass. I don’t understand what ‘frequencies’ you are referring to or in what context you mean.
Sparks,
are you also posting as Hockey Schtick? The text you cited from *your* post is posted under that name.
Here is another link to Fenton’s 2007 study. You should read it.
http://depts.washington.edu/marsweb/papers/PDFs/Fenton-etal-2007-warming-albedo-changes.pdf
The authors investigate a model of albedo changes from Martian dust storms causing changes in climate. Their hypothesis is that internal wind/dust/albedo feedbacks are responsible for large climate variations. It is a very tentative hypothesis, based mostly on two data points – albedo composites twenty years apart. A lot of assumption goes into the modeling. They also note:
At no time do they suggest the presumed climatic change is driven by solar variation (which, at any rate, appears to have exhibited little to no trend for the last 50 – 60 years).
The Triton paper posits changed insolation from orbital dynamics – not increased solar radiation – could be responsible for apparent atmospheric pressure increase and subsequent warming. The authors at no time suggest solar variance is responsible. Orbital variations on decadal time scales are ‘seasonal’ in nature (rather than geologic).
The Jupiter paper does not posit ‘seasonal’ climate change. It posits climate change from processes internal to the planet, not solar variation.
None of these papers (except the last one I observed in my post) posit solar variation as causing climate change.