Click images for more details



Recent comments
Recent posts
Currently discussing

A few sites I've stumbled across recently....

Powered by Squarespace
« New Zealand's temperature record | Main | Snail's pace - Josh 298 »

McLean on clouds

John McLean, of James Cook University in Australia, emails with details of a paper he has just had published in Atmospheric and Climate Sciences about the warming of the planet at the end of the last century. He adds a useful layman's summary.

The paper ...

- indicates that the temperature pattern can be attributed to a sequence of events, namely a shift in the prevailing ENSO conditions, then a reduction in total cloud cover and then a shift on cloud (decrease in low level cloud that was largely offset by an increase in mid and upper level cloud)

- uses the Trenberth, Fasulo & Kiehl energy balance diagram to show that the loss in total cloud cover caused an increase in heat energy being absorbed at the Earth's surface that was greater than the increase that IPCC 5AR claims was due to greenhouse gases

- indicates that greenhouse gases played little if any part in the warming, which not only refutes the IPCC's belief or opinion but also means that there is negligible, or even no, 16 or more years' of "missing heat" to be found.

- shows the changes in cloud cover and temperature both as global averages and then for the six latitude bands each of 30 degrees, the latter indicating the changes in cloud cover applied to most latitude bands except the Antarctic and to a less extent 30S-60S.

- doesn't attempt to identify the reason for the reduction in total cloud cover or the shift from low level cloud.

The paper is open access and can be seen here.

Update 7.52am, 31.10.2014 John McLean commented  at 9.20pm last night that he is a PhD student, not a professor. TM

PrintView Printer Friendly Version

Reader Comments (59)

@ EM

Stable is a relative concept. "Sufficiently stable to sustain life" was the phrase I actually used.

Which is true. If it were not, we would not be having this conversation.

Oct 31, 2014 at 2:24 AM | Unregistered CommenterAnything is possible

Kudos to all the skeptics here, and the skepticism towards both the contents of the paper, and the credentials of it's author. Highly impressive.

Oct 31, 2014 at 5:35 AM | Unregistered CommenterQW

I see I've been "demoted" from being a professor on this page but not yet on the main/home page of the blog.

You'd better fix that one too or someone will accuse me of faking the title, as they did over a similar misunderstanding a few years ago.


[Already done at 7.52am today. TM]

Oct 31, 2014 at 8:18 AM | Unregistered CommenterJohn McLean

"Long term ocean circulation, Svensmark effect, just some internal variability, easy to come up with some possible reasons. Clouds fundamentally cool as they stop the sun's rays reaching the ground in the first place. Just because a cloudy night might keep things warm for a while is a odd definition of 'warming' to me."

Guesswork is fine but you need numbers to buck a consensus. There is obviously an established suspicion in Earth Science about the effects of industrial emissions on the environment and therefore also about the motives of those who defend them. Hence the unscientific requirement to prove the warming isn't from CO2 in order to get published and hence the previous hyped-up scares of global cooling and acid rain from these selfsame fossil fuels.

I think it is smarter to focus on the fact that we already (accidentally) conducted the experiment of hugely increasing the rate of CO2 injection to the atmosphere and the subsequent rate of temperature rise actually reduced, which is a direct refutation of the shaky hypothesis that CO2 is a climate driver. There are another 4 missing fingerprints of manmade warming to back this finding up. Further consolidation would note that there was never any correlation in paleo records between CO2 and temperature anywhere except in the Antarctic which is currently cooling anyway. So CO2 was clearly never more than a feeble feedback in the first place.

Oct 31, 2014 at 10:49 AM | Unregistered CommenterJamesG

@ diogenes

It depends what you mean by characterising uncertainty. There is the analytical / data uncertainty. And there is the methodological uncertainty. Our hypothesis was "That sunny days would on average be warmer than cloudy days" and the data support that hypothesis. One then observes cyclic variation in cloud cover that correlates with cyclic trends in temperature.

The cause of change in cloud cover is not actually important for the conclusions drawn about climate sensitivity. Clive's physics showed that we could not explain all the temperature variance by dClouds alone - I was a bit disappointed in that. But adding a small amount of CO2 GHG provided an excellent fit of observations to "model".

The UK clouds post got aired on Judith Curry. The main criticism there was use of running means to smooth data. Apparently there are better statistical techniques that would have improved and strengthened this work. But I had already spent about 6 months working on this and you just run out of steam.

It began with me wanting to test my child hood memories of climate against reality. Leuchars and Braemar were the nearest climate stations and what should have taken a few hours to have a quick look at temperatures grew into a massive project.

Oct 31, 2014 at 12:16 PM | Registered CommenterEuan Mearns

Further to your update on Mr McLean's credentials. I'd be interested to know which imaginary Phd course Mr Mclean imagines himself to be partaking in...

Oct 31, 2014 at 8:53 PM | Unregistered CommenterQW

Sadly another paper that just blithely accepts the validity of the ISCCP data without any consideration of the literature suggesting that the apparent decline cover is largely if not wholely an artefact of problems with the measurement system - variations in observed cloud cover being dependent on viewing angle from the satellites, changes in the number of satellites involved in the measurements, problems with measuring cloud top height at high viewing angles.

Any paper using ISCCP needs to at least address these questions to some significant degree including justifying why the ISCCP daa should not be rejected as being biased or some attempt being made to correct the data as was done by Clement et al which gave an opposite trend to that reported by McLean.

But there is no mention of any of that. At least some of these papers critical of the ISCCP results should have been discussed in McLean's paper. Yet none of them appear in the list of references. Not good enough to just blithely ignore this. And if McLean was unaware of these studies then the paper was not really of publishable quality.

Berthier, S., Chazette, P., Pelon, J., Baum, B., 2008, “Comparison of cloud statistics from spaceborne lidar systems”, Atmos. Chem. Phys., 8, 6965-6977, 2008,

Campbell, G. Garrett, 2004, “View angle dependence of cloudiness and the trend in ISCCP cloudiness”, 13th Conference on Satellite Meteorology and Oceanography,

Campbell, G. Garrett, 2006, “Diurnal and Angular Variability of Cloud Detection: Consistency Between Polar and Geosynchronous ISCCP Products”, 14th Conference on Satellite Meteorology and Oceanography, [Full text]

Clement, Amy C., Burgman, Robert, Norris, Joel R., 2009, “Observational and Model Evidence for Positive Low-Level Cloud Feedback”, Science 24 July 2009, Vol. 325. no. 5939, pp. 460 – 464, DOI: 10.1126/science.1171255,

Evan, Amato T., Heidinger, Andrew K., Vimont, Daniel J., 2007, “Arguments against a physical long-term trend in global ISCCP cloud amounts”, Geophys. Res. Lett., 34, L04701, doi:10.1029/2006GL028083,

Hatzianastassiou, N., Matsoukas, C., Fotiadi, A. Pavlakis, K. G., Drakakis, E., Hatzidimitriou, D., Vardavas, I., 2005, “Global distribution of Earth’s surface shortwave radiation budget”, Atmos. Chem. Phys. Discuss., 5, 4545-4597,

Knapp, Kenneth R., 2008, “Calibration Assessment of ISCCP Geostationary Infrared Observations Using HIRS”, Journal of Atmospheric and Oceanic Technology, Volume 25, Issue 2 (February 2008), DOI: 10.1175/2007JTECHA910.1,

Norris, Joel R., 2000, “What Can Cloud Observations Tell Us About Climate Variability?”, Space Science Reviews, Volume 94, Numbers 1-2 / November, 2000, DOI 10.1023/A:1026704314326,

Norris, J. R., 2008, “Observed Interdecadal Changes in Cloudiness: Real or Spurious?”, Advances in Global Change Research, 33, DOI 10.1007/978-1-4020-6766-2,

Pallé, E., Goode, P. R., Montañés-Rodríguez, P., Koonin, S. E., 2004, “Changes in Earth’s Reflectance over the Past Two Decades”, Science 28 May 2004, Vol. 304. no. 5675, pp. 1299 – 1301, DOI: 10.1126/science.1094070,

Pallé, E., 2005, “Possible satellite perspective effects on the reported correlations between solar activity and clouds”, Geophys. Res. Lett., 32, L03802, doi:10.1029/2004GL021167,

Pinker, R. T., Zhang, B., Dutton, E. G., 2005, “Do Satellites Detect Trends in Surface Solar Radiation?”, Science 6 May 2005, Vol. 308. no. 5723, pp. 850 – 854, DOI: 10.1126/science.1103159

Rossow, William B., Schiffer, Robert A., 1991, “ISCCP Cloud Data Products”, Bulletin of the American Meteorological Society, Volume 72, Issue 1 (January 1991), DOI: 10.1175/1520-0477(1991)0722.0.CO;2,

Nov 1, 2014 at 3:09 AM | Unregistered CommenterGlenn Tamblyn

I think I've never heard so loud
The quiet message in a cloud.

Nov 1, 2014 at 11:42 AM | Unregistered Commenterkim

Don't worry Glenn Tamblyn, I've seen the disputes over ISCCP cloud data and I believe that the ISCCP have made some corrections. Some of the problems are with the "limits of view range" of satellites and the regions involved amount to three strips along the lines of longitude. These will have limited impact on global averages and even hemispheric averages. I investigated these issues for myself about seven years ago (see and found a very close relationship between ISCCP data to data from Australia's Bureau of Meteorology.

If you criticise cloud cover data I'd like to know if you also criticise CO2 data - Mauna Lao is manually selected as well as probably not representative of European levels - or maybe temperature data - I've found at least 16 inconsistencies with HadCRUT3 data, many of which carry over into HadCRUT4 (e.g. global coverage).

I figure that if all climate scientists were 100% honest almost every paper on climate would say "If the data is correct then ...."

Nov 4, 2014 at 7:29 AM | Unregistered CommenterJohn McLean

PostPost a New Comment

Enter your information below to add a new comment.

My response is on my own website »
Author Email (optional):
Author URL (optional):
Some HTML allowed: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <code> <em> <i> <strike> <strong>