Guest essay by Mike Jonas
I have been looking at some cloud data (from ISCCP: isccp.giss.nasa.gov all available monthly “EQ” data (equal-area grid)) and an interesting question arises. I haven’t seen the answer on WUWT or anywhere else.
Was there a near-global sea-change (no pun intended) in cloud cover around the turn of the millenium, and if so, what caused it?
Figure 1. Global ClearSky anomaly, 1-yr smoothing (centred).
The point is that eye-balling the above graph, it looks like ClearSky was increasing in the late 20thC and then stopped. ie, cloud cover was decreasing, then stopped.
The answer to that question might go a long way towards explaining the “hiatus” and resolving the entire climate science controversy.
If any WUWT readers can supply the answers, I would be most grateful.
– – – – –
A bit of background:
[Except where stated otherwise, graphs in this document are all of temperature anomaly, cloud anomaly over ocean only. The Cloud or ClearSky axis is on the left, Temperature axis is on the right. ClearSky% = (100 – Cloud%), so ClearSky anomaly = (- Cloud anomaly). Cloud anomaly is based on calendar month averages over all full years of cloud data. Temperature data is from UAH Lower Troposphere Ocean-only, provided by UAH in anomaly form but likely to have a different base period.]
There are short term and longer term correlations between cloud and temperature.
Short term (a month or two), cloud increases with temperature. Well, after about 1998 it does. This is only to be expected, because it is generally agreed that the water cycle increases with temperature, and the water cycle necessarily involves clouds. The relationship, as would be expected, is strongest in the tropics.
Figure 2. Monthly Temperature and Cloud anomalies in the Tropics.
Temperature moves first, which suggests that it’s the driver (in the short term). This says nothing about the rate at which the water cycle increases with temperature.
Long term, though, ClearSky increases with temperature. This is the Global picture with 11-yr smoothing:
Figure 3. Global Temperature and ClearSky anomalies, with 11-yr smoothing (centred).
There is no clear indication from the Global picture, as to which comes first, temperature or ClearSky. Temperature appears to trail ClearSky with a lag of a few years in the NH …
Figure 4. NH Temperature and ClearSky anomalies, with 11-yr smoothing (centred).
… and in the Antarctic …
Figure 5. Antarctic (to 60S) Temperature and ClearSky anomalies, with 11-yr smoothing (centred).
… but the pattern is much less clear in other regions.
That temperature increases as ClearSky increases, but with a lag, is to be expected because visible light [and some UV] penetrates many metres into the ocean thus warming it; reflective clouds affect the amount.
The IPCC claim a large positive cloud feedback (ie, that a rising temperature causes more warming by clouds [presumably they mean that higher temperature leads to less clouds, but I can’t see anywhere that they say it explicitly]. A long time ago I explained on WUWT how the way in which they derive the positive cloud feedback was invalid (https://wattsupwiththat.com/2015/09/17/how-reliable-are-the-climate-models/). The fact that the initial effect of temperature on clouds is in the opposite direction (Figure 2 above) suggests that the IPCC finding is mistaken, and that ClearSky is simply a significant driver of temperature over decadal+ periods.
It’s perhaps a bit odd that the ClearSky effect on Temperature is most visible in the Antarctic and the NH. I speculate as follows:
The period covered by the cloud data is simply not long enough to get a clear picture of the longer-term mechanisms. There are also a lot of other things going on which confuse the picture. For example, there are winds and ocean currents that flow from region to region, so regions are affected by what is going on in other regions. Over periods of a year to multiple decades, temperatures everywhere are affected by ENSO and other ocean oscillations. Clouds are presumably affected too. And then there is the short term effect of temperature on clouds, which is in the opposite direction to the longer term cloud-temperature relationship, and hence may confuse the picture further. And, of course, we always have to bear in mind that climate is a non-linear system.
ENSO in particular is strongest in the Tropics and south of the Tropics, and maybe this would make the cloud-temperature link more difficult to see there, particularly given the short period over which we have cloud data. Maybe that is why the ClearSky-Temperature lag is most visible in the Northern Extra-Tropics and the Southern Ocean.
The Southern Ocean is more isolated than other regions, if I have understood it correctly. It has virtually no incoming winds or surface currents from other ocean areas. The principal incoming ocean current is in the form of upwellings from the deeper ocean, and is therefore unaffected by weather/climate conditions in other ocean areas. Similarly, the principal wind direction is from the Antarctic continent (the katabatic wind) not from other ocean areas.
All other ocean areas, by contrast, have incoming surface ocean flows and winds from other ocean areas, and are therefore influenced by weather/climate conditions in those other ocean areas.
One implication of this is that the cloud-temperature relationship is more likely to reflect locally-generated conditions over the Southern Ocean than it is over other ocean regions. The fact that solar radiation is weakest there per unit area would suggest that a smaller temperature effect should be expected, but the effect appears to be just as strong.
The cloud-temperature relationship in the other ocean regions, as covered by UAH, is less clear than in the Southern Ocean. See worksheet Graphs in spreadsheet UAH_ClearSky.xlsx (Excel .xlsx 1.2 mb)
Mike Jonas (MA Maths Oxford UK) retired some years ago after nearly 40 years in I.T.
Re: A Cloudy Question: was ‘the pause’ caused by a change in global cloud cover?
For a moment or two, think about a global model for climate, which, after all, is defined as a global phenomenon. Global warming is a thermodynamic problem, which, like all thermodynamic problems, involves macrophenomena. Meso- or microphenomena, like cloudless patches, tropical peculiarities, ENSO, or tropospheric lapse rates, are distractions. They consist of temperature distributions that ride on top of the global averages, that is, climate.
Think of the Kiehl-Trenberth budget that IPCC animated to create their Radiative Forcing model as IPCC thought of it, as a picture of global climate. AR4, Figure FAQ 1.1. There is one global cloud cover percentage involved. The surface, the atmosphere, and the top of the atmosphere are single nodes representing in all respects some sort of (weighted) averages for the entire Earth. The surface is ocean because landmasses and their local atmospheres have minimal heat capacities (climatologists call heat capacity inertia) to contribute to the whole.
In this schema, cloud albedo is the most powerful feedback in all of climate. That comes from gating the Sun on and off, switching the overwhelmingly dominant source of Earth’s thermal energy. Cloud albedo is proportional to cloud cover, which responds to both the Sun and to humidity. (It does not respond to any significant degree to CCNs because CCNs are in surplus in the atmosphere, and because the ocean creates them. This explains why GCRs have no significant effect. If the atmosphere had a surplus of humidity, it would act as a cloud chamber to GCRs. It doesn’t.)
Clouds form overnight due to atmospheric cooling and then burnoff in the morning heated by the Sun. Thus burnoff amplifies variations in the Sun, amplifies TSI, and is a positive feedback to the Sun. Cloud cover also increases as surface temperature increases, thereby increasing albedo, and creating a (powerful) negative feedback to warming from any imaginable cause.
IPCC parameterizes cloud cover as constant — regional perhaps, but globally constant. That kills the dominant feedback in climate. At the same time, however, IPCC increases humidity according to the Clausius-Clapeyron equation. IPCC may also vary cloud albedo but by varying the reflectivity per square meter of clouds, and not by varying cloud cover, the square meters. For this global model, just keep the reflectivity constant. It is trivialized by cloud switching of the Sun.
IPCC creates a positive cloud feedback to surface warming by increasing water vapor according to the C-C relation. This tends to make its RF model work by amplifying the CO2 response, which turns out to be too weak to cause a scary enough Greenhouse Effect. So again, IPCC creates not only a positive cloud feedback, but an increasing one, all in the effort to make its CO2 story work. IPCC zeroes cloud cover changes and the really big twin feedbacks of climate.
Cloud cover lags both the Sun and surface warming a bit. But surface warming or cooling lags the cloud cover-amplified solar radiation to the surface by a couple of long time constants, roughly one and a half and a half century. See SGW, rocketscientistsjournal.com.
Science doesn’t require models to have any fidelity to real world phenomena. It does require models to work, i.e., to have predictive power factually validated. But once a model fails the test, it is open to criticism for unreal physics.
Most interesting, Jeff
Are you, in summary, agreeing with my strongly held view (though I can substantiate it but poorly myself) that the hydrological cycle involving evaporation from the ocean, and atmospheric humidity/clouds acts as a thermostat for the global system? Without it, it is very difficult to explain the observed short/medium term stability of the climate. Willis E has posted some stuff on mechanisms, and so have others. Should we not be looking for model physics in which a water thermostat is a basic assumption, and see what falls out? THEN see what sort of CO2 ECS numbers we get?
If Jeff isn’t I am. Here’s the mechanism
details
https://micro6500blog.wordpress.com/2016/12/01/observational-evidence-for-a-nonlinear-night-time-cooling-mechanism/
Does this “. . . IPCC increases humidity according to the Clausius-Clapeyron equation.” mean they consider the entire atmosphere to be always saturated with water vapor?
I don’t think so, but worse, saturated would be noticeable.
They have a “mass conservation”, that they use to enforce this relationship. The equation that is a parameterization of water evaporation didn’t generate enough water vapor feedback
here http://www.cesm.ucar.edu/models/atm-cam/docs/description/node13.html#SECTION00736000000000000000
It is why models are warm, it was this “fix” that warmed them up in the 80’s, that they have been using aerosols to tune down, until we got better aerosol data.
Jeff G – You hit the nail on the head: “IPCC parameterizes cloud cover as constant — regional perhaps, but globally constant. That kills the dominant feedback in climate.“. I think that the data I have presented here shows a strong possibility that global cloud cover can change independently, and significantly, and thus that the IPCC have got it wrong. A longer data period would really help, but we can only work with whatever data is available.
Taken at face value, clouds are a short term feedback to temperature changes and a long term forcing of temperature. This is similar to Spencer Braswell 2011 in which they were criticised heavily by Dessler and the green mob. Makes more sense than LWIR heating of the ocean due to CO2. Bob Tisdale, isn’t this part of your suggestion that ENSO is driving climate?
Cloud forcing has been calculated at least in two papers and it is 0.11 C/cloudiness-%. It means that 1 % cloudiness change causes 0.11 C degrees change in global temperature. It is fairly easy to calculate from three measurable operating points of the Earth (cloudiness / albedo): = (0% , 53/342), (66 %, 104.2/342), (100%, 120/342). It means that the overall temperature increase of 0.85 C degrees since 1880 could be explained by the cloudiness decrease of 8 %. Of course there are other factors included.
Interesting. I thought the change in cloudiness to explain modern warming was in the 1%-2% range.
That is oversimplified. A 1% change in TROPICAL cloud cover will have a much greater impact than a 1% change elsewhere.
I just answered your question
here
https://wattsupwiththat.com/2017/01/08/lago-enriquillo-redux/#comment-2393105
and read the comment after that
About the time of the “sea change” in clear sky is about the time China began massive increases in coal power production. I would be interested to see the relationship between China’s coal power production and cosmic ray counts in addition to temperature with regard to clear sky.
@Mike Jonas
“If any WUWT readers can supply the answers, I would be most grateful”
I suggest you contact Willis Eschenbach; he has posted several interesting articles ( to the best of my poor memory ) about the subject(s) of you post.
It’s the sun, smart guy.
This question of clouds reminds me of Global Dimming, and Global Brightening. Of course both ideas demanded lots of grant money to investigate.
we’ve been debating the cloud issue for years. I hold the (apparently minority) opinion that cloud cover can change without being caused by a temperature change, that is, clouds can act as a sort of forcing of climate change. I call this “internal radiative forcing” (as opposed to extrenal radiative forcing, e.g. from CO2), and we’ve published on it and I’ve blogged on it for years. Andy Dessler, in contrast, claims that all cloud changes are the result of feedback in response to a temperature change. So, in answer to the original question posed, it is indeed possible the pause was caused by a change in cloud cover.
Roy: As an outsider, it seems perfectly logical that changes in cloud cover can cause temperature change. However, I think it is self-defeating to say that clouds can “force” climate change. Forcing is caused by things that influence the radiative balance at the top of the atmosphere by a mechanism that is independent of surface temperature. Clouds clearly respond to surface temperature and therefore are feedbacks. We have naturally-forced variability and anthropogenically-forced variability. However, anthropogenically-forced variability is so slow that unforced variability (ENSO, probably AMO and PDO) is a bigger player in the decadal changes that alarmists calling “climate change”. So why not call it “unforced variability in cloud feedback” or “internal variability in cloud feedback”. Certainly chaotic changes in ocean currents and upwelling cause change in the cloud above that can persist for a long time – almost certainly for decades – even though the clouds themselves only last for a few days.
If we properly define climate change as the difference between two periods of 30 years or longer, we don’t have the data needed to determine what role “unforced changes in cloud feedback” have played in climate change.
Because he is saying that it is both a forcing and a feedback.
That the cloud changes happen FIRST.
MikeN: Variability in our climate like ENSO (presumably and AMO and PDO) are not normally referred to as “forced change”. It is the result of deterministic chaos. Clouds can change for similar reasons.
Given that the average water molecule spends about 9 days in the atmosphere between evaporation and precipitation and that clouds (suspended water droplets) last for a shorter period of time, it is awkward to say that clouds “force” much of anything. This language tends to produce a closed minded attitude, so I’m trying to express this concept in other terms. The best I can come up with is to suggest that a chaotic change in the ocean can drive a PERSISTENT change in cloud cover, either local or distant. (At the moment, changes in clouds over the Western US seems to be driven by events around Hawaii.) So I’m suggesting we more clearly link cloud “forcing” to unforced variability in the oceans. Above I suggested “unforced variability in cloud feedback”, but that is WRONG, because feedbacks are only important average a forced change. Unforced variability in albedo?
I agree Roy (like that really matters, but). The blob, was a high pressure zone(tend to clear skies), with iirc winds going around it, so it becomes self-reinforcing. Like a thumbprint that doesn’t go away (whatever caused it in the first place).
“…cloud cover can change without being caused by a temperature change”
O.K., Dr. S., but what exactly is causing the change in cloud cover then? (what specifically happened there at the turn of the millenium?)…
I think the oceans shifted warm water north of the equator at the end of the el nino, since min temps follow dew points, more water vapor blew across more thermometers than about anywhere else on the planet, the band of 20-30,35 North Latitude.
He is not pegging 2000 as the change point, but an earlier time. That the global warming seen since the 1970s was caused by changes in cloudiness, and this forcing is being misdiagnosed as a positive feedback of CO2-caused global warming, thus making the amount of CO2-caused global warming even higher.
Roy – I think that the data I have presented supports your opinion that cloud cover can change without being caused by a temperature change, that is, clouds can act as a sort of forcing of climate change. The fact that cloud decrease appears to precede temperature increase by a few years in large regions (with no clear relationship elsewhere) suggests very strongly to me that clouds in their own right are driving temperature. I tried to say that in the article, but very cautiously as I didn’t want to jump to unjustifiable conclusions. If only we knew what caused the cloud changes …….
Mike: Interesting article. I agree with some commenters above that changes in cloud cover are not a direct measure of changes in SWR absorbed. So the next step might be to look at CERES data for incoming and reflected SWR. Then you can see what effect clouds have on SWR absorbed and what effect absorbed SWR has on temperature.
The following might provide a reality check. Given the heat capacity of a 50 m mixed layer of the ocean and the atmosphere, a +1 W/m2 radiative imbalance is capable of warming at an initial rate of 0.2 K/yr – if all of the heat remained in the mixed layer. The current 30% albedo (some at the surface) reflects 100 W/m2 back to space, so a 1% change is roughly 1 W/m2 or a drop of 0.3% in albedo. In practice warming will be less than this. First, as the planet warms it will radiate more heat to space, counterbalancing the increase in absorbed SWR. A black body (the Earth without feedbacks) at 255 K radiates 3.8 W/m2 more for every degK rise or 3.8 W/m2/K. If you think feedback is positive and climate sensitivity is 2, 3 or 4 K (take your pick), this becomes 1.9, 1.27 or 0.95 W/m2/K. Also as the mixed layer warms, some of that heat disappears into the deeper ocean.
Paul_K did an excellent analysis of both phenomena during Pinatubo. He finds that about 2.7 W/m2/K left the surface/atmosphere/mixed layer for space (TCR 1.4) and 2.8 W/m2/K left for the deeper ocean and the effective depth of the mixed layer was about 35 m. So if an instantaneous reduction in cloud cover produces a radiative imbalance of 1 W/m2, warming at a rate of 0.3 K/yr would begin, but by the time warming had reached 0.1 K (4 months), heat loss to space and the deep ocean will be consuming about 0.55 W/m2 and the rate of warming will have been cut in half. Of course, if climate sensitivity is higher or other factors are different, a radiative imbalance can produce more warming.
http://rankexploits.com/musings/2012/pinatubo-climate-sensitivity-and-two-dogs-that-didnt-bark-in-the-night/
I have long been of the opinion that the retreat of alpine glaciers is better explained by a decrease in daytime cloudiness than by global-average temperature increases of a fraction of a degree over decades, most of which occurs at night and in the Winter. In Glacier National Park (USA), it appears that the glaciers with a south-facing aspect have retreated rapidly, while those in the shade on the north slopes have been more stable. I personally observed a significant retreat of the Fox Glacier (NZ) in the 1980s, when global temperature increases were low. I think that focusing on CO2 has blinded climate scientists to many other things that are occurring simultaneously.
so true.
and focusing on “global warming” has blinded media and politicians to many other, far more important, things that are occurring, too.
Focus on a microscopic aspect of a minute non-problem. Storm in a teacup.
https://isccp.giss.nasa.gov/climanal.html
Mosh, me do science? Naah, we both know it’s much more fun abandoning sceptical science and just doing clever flyby comments on WUWT.
“I’ve looked at clouds from both sides now.” Daytime clouds reduce temps, night time clouds reduce heat loss. More daytime clouds=cooling, more night time clouds=warmer. Anyone got a chart showing clouds by day vs night over the years in question? Also, as pointed out above, latitude of same would be a factor. Relate these to global temperature might be enlightening, though a little complex given seasonality of where the sun shines and where it does not at higher latitudes north and south.
Sure…lots of chapters are here…..https://reality348.wordpress.com. All effort from Erl Happ.
Because CO2 forcing cannot explain the temperature decrease during the Little Ice Age and on the other hand IPCC’s CO2 forcing gives now 44 % too high values, the conclusion is that there are other forces in this game. Those forces are: solar radiation changes and harmonic cosmic resonance forces. Both these forces work in the final phase through cloudiness changes. Cloudiness changes affect the albedo and the Earth is very sensitive for the albedo changes.
These cosmic forces are the reasons for the natural temperature variations as expressed by IPCC. This time I agree completely with IPCC. They are natural forces which have a big role in the global warming.
Earth average temperature is indeed very sensitive to albedo changes and also to changes in average cloud altitude as shown by a simple thermal analysis at http://lowaltitudeclouds.blogspot.com
I think my climate nursery rhyme sums it up, only time will tell.
Mother Goose on Climate Prediction
As record winds blow
Unprecedented snow,
Oh, where is our globe a’ warming?
That depends on the sun
And the ways oceans run,
Plus clouds (with complexity) forming!
Now, and for quite long,
Climate models are wrong.
So, what caused the pause in the warming?
Yes, look to the sun,
The ways oceans run,
And the clouds, in complexity forming.
CO2 is “too small”
To stop temperature’s fall
When the sun, clouds and oceans together,
Begin to cause cold
in a cycle so old…
That no one alive can remember!
So if I do some harm
By just keeping warm,
You’ll have to kindly forgive me!
I find my solution
Is carbon pollution…
Ere Gaia would quickly outlive me!
Is there any correlation with the western clean air acts being introduced, reduction in sulphate aerosols in the atmosphere leading to less nucleation and so less cloud?
The anthropogenic contributions to particulates and aerosols are small in comparison to natural sources. What more likely contributes to cloud nucleation is the cosmic ray flux. The heliospheric density and global temps tend to correlate.
After years of mindless repetitions of ‘hottest ever’ years, it is refreshing to read an article about clouds which have remained the elephant in the room of Climatology. Mostly clouds are ignored although their effect can be massive. Modelling of clouds seems non-existant. Climate stations have been recording cloud cover for years so there should be no lack of data to work with. Clouds during the day hinder heating and clouds at night have the opposite effect on surface temperature. What is missing is a detailed understanding. CO2 can take a back seat.
the link posted by mosher above is worth a click.
or maybe not if bill illis is correct.
I think we should get Willis to run the CERES and ERBE cloud cover data again.
I hate to say this, but GISS under James Hansen managed the ISCCP cloud project and nobody really believes the numbers that came out of it – even the climate scientists who believe anything that helps the cause of more grant funding.
Bill Illis,
There is an alternative. For decades, the USGS evaluated Landsat satellite imagery by estimating the cloud cover as an aid to users. That is, giving the users some assurance as to how much if any of the image was cloud free. All that data exists in archives and could be analyzed to see if it agrees with what NASA has published.
It’s the Sun. As solar activity decreases, it affords us less protection from the bombardment of cosmic rays from space. Cosmic rays act to seed clouds, which has already been established in the CERN cloud chamber. So with heavier cosmic ray bombardment we get more cloud cover. If the Sun does go into a minimum in the next few decades, as predicted by several solar scientists, the Earth will cool considerably. At least it will once and ever quash the idea that climate is regulated by CO2.
Except for the fact that when the shift happened (circa 2000) we were not only headed toward a solar maximum, but SC23 was still a fairly strong cycle…
Why did cloud cover measurements stop in 2009? isn’t it an essential part of climate science?
We are missing 17 years of data
I already made the same question. Why there is no global cloud data available? Bill Illis wrote that we should look at CERES and ERBE cloud data. Could you please show what are the links to these data sets?
RE Aerosols. I thought it was Bit Chilly who wrote that aerosol levels are saturated, but I can’t find the post so it could have been anyone, my apologies.
I’m not sure that is the case. If you Google ‘nasa ship tracks biscay’ you will see images of what happens when you add aerosols to an already well aerosoled* boundary layer The tracks which look like contrails have much higher albedo even when they are in areas which are already cloudy. This effect was the basis of Latham’s cloud ship proposal, which also comes up on that page.
Bit Chilly is sound on plankton and DMS. The possibility of a major biological climate effect is very downplayed. A bloom of Emiliania huxleyi for example will alter albedo directly, and loss of that tiny denizen would also reduce CO2 pull down.
JF
*Sorry about that.
My 2 cents – Lat nailed it at the very top with ‘chicken & egg’
i.e. Did The Pause cause The Clouds or did The Clouds cause The Pause
Then a load of peeps confused themselves confusing feedback and amplification. sigh
Thinking that The Clouds did it is similar to a lot of Climate Scientist’s writings about clouds – I really get the impression they imagine that Eath has been endowed with a certain, fixed and immutable number of clouds.
These clouds then manouver themselves around the planet causing weather and climate to occur, at certain places & times, in the manner that (presumably) some greater power deems to be required at said places and at said times.
Clouds are weather, weather is clouds – in the same way fish can swim, birds can fly, LWIR is temperature and temperature is LWIR.
They are inseperable, one does not cause the other.
And this is where the chronically depressed brain comes in.
To such a brain, one thing *has* to cause the other. The depressed brain needs that because then it has that thing under its power and control. Climate Change science sound familiar here????
Things not in the control of the depressed brain are very scary, such things may do unpredicatable actions and the depressed brain instinctively knows it is not able to respond either quickly or appropriately. Unknowns are a deadly threat and we see that happening everywhere. From the massively increased surveilance in the UK (supposedly to counter terrorism) to the Social Cost of Carbon.
Its all about control because otherwise, whatever it is scares the he11 out of the muddled, (physically and mentally) slow and depressed brain.
And our dependance on glucose (carbohydrate food) is The Root Cause of that.
This is why there is such a strong correlation with sunspots. The solar wind shields the earth from gamma rays which are part responsible for cloud formation. There was an essay on this site about it a number of months ago.
This conversation prompted me to email the ISCCP, and ask them a question:
This morning I got a reply:
If there was, it was the cause of the step in temps after the El Nino, NOT co2. 🙂
Considering feedback discussion, the solar constant is 1(100%). Everything inside the system (earth) is less than that. Which menas everything that happens on earth is MASSIVE negative feedback.
There is nothing to worry about.
/thermodynamics