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
The decrease in Cloud Cover that this new paper found is even more dramatic than Dr. Spencer’s 1-2% variations in Cloud Cover figure. It finds a decrease in Cloud Cover that is -1.6% PER DECADE for about 5 decades, which suggests that Cloud Cover may have an even larger role on Climate Change than even Dr. Spencer suggests, taking this study verbatim.
This could have significant implications for Climate Change, if the study’s results are to be correct.
Just wanted to throw that out there.
Leif Svalgaard says: April 5, 2012 at 6:10 am
As vukcevic states:
Most of what he says is pure nonsense. [and he is proud of it…]
Hi doc
Nice to see you back firing on all cylinders after the WUWT dinner.
http://www.vukcevic.talktalk.net/Team.htm
Snowlover123 says:
April 5, 2012 at 5:52 am
So if Cloud Cover is decreasing, and the trend is statistically significant, couldn’t this verify the ACRIM composite which shows a statistically significant trend upward between Solar Cycle minimas over the last 30 years?
You are putting the cart in front of the horse here. There is no such trend.
http://lasp.colorado.edu/sorce/news/2011ScienceMeeting/docs/presentations/1g_Schmutz_SORCE_13.9.11.pdf slides 31 and 33:
“Observed data do not support a measureable TSI trend between the minima in 1996 and 2008 !”
Lief, I find it interesting you raised the non-effect of the solar cycle to climate sensitivity so quickly without any apparent reference to the solar cycle by the authors of this study. Why?
I take it then you completely disagree with Svensmark’s finding on GCR influence on cloud formation? Or maybe you still have your doubts?
Snowlover123 says:
April 5, 2012 at 5:52 am
ACRIM composite which shows a statistically significant trend upward between Solar Cycle minimas over the last 30 years?
Slide 17 of http://lasp.colorado.edu/sorce/news/2011ScienceMeeting/docs/presentations/1d_Willson_LASP_TRF%20diagnostic_for_ACRIM3_implications_TSI%20database.pdf
There is no such trend.
Leif Svalgaard says: As you can see, activity was low broadly around 1900 and 2010 and high in between. If the Sun modulates climate in any significant way, the climate now should resemble that of the early 1900s. Does it?
Arent you the same guy who has been telling us for months that this solar cycle more closely resembled minima 1954 http://www.leif.org/research/F107%20at%20Minima%201954%20and%202008.png Well, ya missed that one.
And according to this chart, there were several low solar cycles leading up to and after the 1900s http://solarscience.msfc.nasa.gov/images/bfly.gif So why pick the one in the middle to use as your proof? If you take a boiling pot off the heat, it doesn’t immediately go cold. Sheesh. I don’t understand why you just cant admit that you really haven’t seen everything the sun is going to throw at us and as far as your science goes, its still an infant when compared with the sun’s history. What about the new studies showing that solar activity adds a lot of energy into the upper atmosphere. Wheres your chart of that? I respect you sir, but sometimes your hubris just kills me.
Leif Svalgaard says:
April 5, 2012 at 6:10 am
“Slide 2 of http://www.leif.org/research/SHINE-2011-The-Forgotten-Sun.pdf shows solar activity since 1840 [sunspot number, geomagnetic activity, and the magnetic field in the Heliosphere]. As you can see, activity was low broadly around 1900 and 2010 and high in between. If the Sun modulates climate in any significant way, the climate now should resemble that of the early 1900s. Does it?”
Leif,
I do not know if you agree that there have been long term (order of 1000 Y or so) varying trends, which include the medieval warm period, little ice age, and present warm period. You should, as data is strongly supporting this. The level of the present warm period is the order of if not cooler than the MWP. Why do you insist that shorter trends due to causes such as solar variation, superimposed on longer trends (for whatever their cause) need to agree in absolute level? They are riding on the longer term trend, so different times have different reference levels. Why do you think the level of early 1900’s should be a factor in the 2010 period if the recovery from the obviously unusual LIA gives a trend that extended the full 20th C? If you now examine recent trends in temperature, you may note the recent warm period has leveled off and likely will tend down from here.
pkatt says:
April 5, 2012 at 7:32 am
Arent you the same guy who has been telling us for months that this solar cycle more closely resembled minima 1954
Not at all. You have the year wrong. Compare the current cycle to cycle 14: http://www.leif.org/research/SC14-and-24.png
If the Sun modulates climate in any significant way, the climate now should resemble that of the early 1900s. Does it?
Or rather, since the Ocean is a buffer with timescales that are decades to centuries long, the climate should barely have started changing back to what it looked like in the late 1800s. And perhaps it has. We won’t know for sure for up to 1-3 more solar cycles, will we?
It’s not like temperatures instantly spiked up in association with solar state, is it? Decadal lapses, or even longer, are absolutely to be expected when the small variations in net insolation have to heat up a kilometer or so of the ocean that covers 70% of the planet to make a significant secular change in average temperature.
rgb
pkatt says:
April 5, 2012 at 7:32 am
Sheesh. I don’t understand why you just cant admit that you really haven’t seen everything the sun is going to throw at us and as far as your science goes, its still an infant when compared with the sun’s history.
But you think that everybody else has?
What about the new studies showing that solar activity adds a lot of energy into the upper atmosphere. Wheres your chart of that?
On slide 9 of http://www.leif.org/research/POES%20Power%20and%20IHV.pdf
And that energy is extremely small [like 1000 trillion times smaller] compared to the ordinary heat and light that gets to the lower atmosphere where you live.
Leif Svalgaard says:
April 5, 2012 at 8:32 am
And that energy is extremely small [like 1000 trillion times smaller]
should be a million times smaller. sorry for my error. [too many zeroes 🙂 ]
From the top post:
The cited paper actually talks about cloudiness in the rest of the world. It’s suprising that this section hasn’t been quoted seeing as it is germane to the implications being made here and at The Hockey Schtick.
While projections of global trends indicate more cloudiness and water vapour, it is also projected that some areas will become drier and some wetter.
Leif Svalgaard says:
If the Sun modulates climate in any significant way, the climate now should resemble that of the early 1900s.
Absolute nonsense. That is like saying that if day length modulates climate in any significant way, then March temperatures should resemble those of September. It isn’t just (one of the many) instantaneous inputs to the system that define a system’s state, it is also the initial conditions.
Leif understands this. For him to make these silly arguments belies a distinct lack of … well, lets just leave it at “objectivity.”
Robert Brown says:
April 5, 2012 at 8:06 am
And perhaps it has. We won’t know for sure for up to 1-3 more solar cycles, will we?
I don’t see people pushing the Svensmark idea dealing with decade/centuries long time lags. Perhaps you could show me some? Now, the main modulator of cosmic rays is the geomagnetic field which has decreased 15% the past 150 years. This should have increased the GCR flux during that time, with a cooling as the result. Has the climate cooled the past 150 years? Or perhaps the time lag is longer, maybe 1000 years or more. Maybe the GCRs that are active have so high energy that they are not modulated by the Earth’s field, but then they are also not modulated by the Sun, or perhaps one need some special pleading: the GCRs are JUST energetic to be solar modulated, but JUST not enough to be modulated by the Earth.
Robert Brown says:
April 5, 2012 at 8:06 am
the climate should barely have started changing back to what it looked like in the late 1800s.
And in the late 1800s it had barely started changing back to what it looked like in the late 1700s at which time it had just barely started changing back to what it looked like in the late 1600s, at which time it had barely…
JJ says:
April 5, 2012 at 9:39 am
That is like saying that if day length modulates climate in any significant way, then March temperatures should resemble those of September.
And they do, more than they resemble those of December and those of June. Now, don’t get confused about the time scales: climate is a many-year average, not on a month scale, but that is perhaps too silly for you.
Leif Svalgaard says:
April 5, 2012 at 7:00 am
You are putting the cart in front of the horse here. There is no such trend.
slides 31 and 33:
“Observed data do not support a measureable TSI trend between the minima in 1996 and 2008 !”
———————————————————————–
That’s interesting, considering the new paper stops in 2005, and you have data continuing all the way to 2008, to try and somehow disprove the data that ended in 2005.
Leif Svalgaard says:
April 5, 2012 at 7:23 am
Slide 17 of http://lasp.colorado.edu/sorce/news/2011ScienceMeeting/docs/presentations/1d_Willson_LASP_TRF%20diagnostic_for_ACRIM3_implications_TSI%20database.pdf
There is no such trend.
———————————————————————————
I take it you haven’t read Morvdinov and Willson 2003, (http://pubs.giss.nasa.gov/docs/2003/2003_Willson_Mordvinov.pdf) which found a statistically significant trend upward in TSI between the minimas of SC 21 and 22 from the ACRIM TSI composite?
Snowlover123 says:
April 5, 2012 at 10:30 am
That’s interesting, considering the new paper stops in 2005, and you have data continuing all the way to 2008, to try and somehow disprove the data that ended in 2005.
———————–
That was terrible wording on my part.
The new paper’s Cloud data stops in 2005, and you have TSI data going all the way to 2008 to somehow disprove the solar connection with the Cloud Cover decrease.
Snowlover123 says:
April 5, 2012 at 10:30 am
“Observed data do not support a measurable TSI trend between the minima in 1996 and 2008 !”
That’s interesting, considering the new paper stops in 2005, and you have data continuing all the way to 2008, to try and somehow disprove the data that ended in 2005.
Snowlover123 says:
April 5, 2012 at 5:52 am
ACRIM composite which shows a statistically significant trend upward between Solar Cycle minimas over the last 30 years?
In my book, the ‘last 30 years’ include 2008.
Snowlover123 says:
April 5, 2012 at 10:34 am
I take it you haven’t read Morvdinov and Willson 2003, (http://pubs.giss.nasa.gov/docs/2003/2003_Willson_Mordvinov.pdf) which found a statistically significant trend upward in TSI between the minimas of SC 21 and 22 from the ACRIM TSI composite?
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.
Snowlover123 says:
April 5, 2012 at 10:36 am
The new paper’s Cloud data stops in 2005, and you have TSI data going all the way to 2008 to somehow disprove the solar connection with the Cloud Cover decrease.
No, I have solar data going all the way back three hundred years showing no convincing solar connection with climate. Now, you may want to respond to people who claim that there is a decade/century long time lag between the sun and climate. Or are you one of those who believe there is no lag?
What is the process that causes the estimated 11 year sun spot cycle?
Lately I’ve been looking at the positions of the outer planets in relation to sun spot minimum and sun spot maximum (just out of interest) I’m currently working on the math, but I have noticed that there is or appears to be a cycle of about 11 years related to the total planetary mass of Jupiter, Saturn, Uranus and Neptune and their periodic solar distribution. Like I said, I’m only studying this out of interest and I haven’t completed the math yet but what I’ve seen is very interesting, where it appears to take Roughly 11 years for the outer planets to become evenly balanced to becoming unevenly balanced, and there are various configurations of this that seem to coincide with lower or higher sun spot activity. A good way I can think of explaining this is that the outer planets are behaving like a giant weights sitting on a giant scale and the sun is the pivotal point, the scale moves up and down every 11 or so years and depending on the configuration of the weights the scales can tip higher or lower. It’ll take a further month or two for me to finish my study on this. I thought that the solar buffs here might have a thought on this.
Despite last month’s Forbush confirming Svensmark’s hypothesis (Dr. Svalgaard failed to notice it, accidentally of course)
http://www.vukcevic.talktalk.net/Ap-Cl.htm
GCRs may not be sufficiently potent to explain major temperature oscillations (Roman WP = RWP, MWP, LIA and 20th century WP = TCWP).
The alternative idea as condensed in here
http://www.vukcevic.talktalk.net/GTCa.htm
will get some traction when all the alternatives are thoroughly and systematically trashed by experts from the opposing camps.
Sparks says:
April 5, 2012 at 11:14 am
………….
Something like this
That word is BANED on the WUWT don’t you know?
Leif Svalgaard says:
April 5, 2012 at 10:56 am
“there is no observational evidence for any persistent trend in TSI at mimina.”
Does minimal Sun Spot number correlate with Northern hemispherical minimum temperatures?