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Why global mean temperature is not a valid scientific measure for global climate change.

Posted by Frank Lansner (frank) on 1st April, 2010
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By Birger Wedendahl.

In Denmark we have an ongoing discussion on whether Global Mean Temperature  GMT is a valid proxy for global heat balance/ global warming. Professor in thermodynamics, Bjarne Andresen, explains that one cannot simply add temperatures and then divide them to get at mean temperature in a non equilibrium thermodynamic system.
Asymmetric Hemispheres

Fig 1.  
Our planet is asymmetric. In the Northern Hemisphere 39% of the area is land.
In the Southern Hemisphere only 19% is land. This means twice as much continent on the NH as on the SH
Due to the heat capacity of the oceans and the huge amount of water moving vertically and horizontal oceans absorb almost 90% of all absorbed energy on Earth.
Antarctica makes the Southern Hemisphere very cold because of ice albedo , cold winds , and sea- and glacier ice cooling the air and surface of the ocean. The waste ocean area also results in a lot of cooling because of evaporation.
Whereas a reduction in ice albedo in the Northern Hemisphere when exposed to increasing temperatures makes the Northern Hemisphere more vulnerable to global warming.
This means you need a lot more energy to warm up the Southern Hemisphere by 1 degree Celsius than you need to warm up the Northern Hemisphere by 1 degree Celsius.
Maps showing actual warming and models of global warming illustrate how the Northern Hemisphere warms up much faster than the Southern Hemisphere and several degrees Celsius more if exposed to the same amount of increased infrared radiation.
Map illustrating temperatures at the end of this century caused by increased emission of greenhouse gasses.

Fig 2. 
Source: DMI  Danish Meteorological Institute.
Map showing a more sensible Northern Hemispheric reaction to temperature change.

Fig 3.

Fig 4.
Between 1910 -1940 most of the warming up took place in the Southern Hemisphere whilst most of the warming up during 1975-2005 took place in the Northern Hemisphere.
This means that globally more heat was needed to warm up the lower troposphere early in the century than later in the century. We are told by IPCC that warming up between 1910 -1940 is allegedly natural whilst warming up during 1975-2005 is said to be anthropogenic . This is very interesting. We are always told that the actual warming up is unprecedented.
To illustrate the case I will make a small calculation.
If the Northern Hemisphere warms up 1 degree and the southern atmosphere cools down 1 degree you have a temperature sum of zero. But actually you loose
energy, because it requires more energy to restore the energy in the south than you get from warming up the north.
Heat balance is a better proxy for global warming but it is very difficult to estimate.
On the other hand global mean temperature is so very biased that it has very little relevance when you wish to describe changes in global warming.

Birger Wedendahl,


- A few comments by Frank Lansner:
In the Atlantic Ocean we have a possibility to redistribute heat from South to North.

Fig 5.
 As Birger Wedendahl mentions, there is much more land area on the Northern Hemisphere than on the Southern Hemisphere. Heat that is transported to the Northern Hemisphere is likely to spread out over the vast land areas. When measuring global temperatures as a simple mean of the surface area, then a simple redistribution of heat from South to North is then likely to appear as a global warming trend.
The AMO index that describes the heat of the Northern Atlantic appears oscillating, at least in the 20´ieth century:

Fig 6.
According to the AMO, one might expect extra “global” warming around year 1940 and around year 2000.
So, the mix of land area and ocean area used for simple temperature mean for the globe might enable global temperature fluctuations simply by redistribution of heat.
An area more comparable to take a simple temperature mean would be the oceans only. (or land, however, Oceans obviously have more stable temperatures). So, perhaps Ocean temperatures are a more proper indicator of temperature trend of the earth:

Fig 7.
Assuming the 70% of the planet – the Oceans – gives a better impression of the warming trend, it becomes obvious that the global warming 1940-2010 was only 0,25-0,3 K.
Further more, we see that the “global warming” was much faster 1910-40 than at any point after 1940….   !

Last changed: 3rd April, 2010 at 16:25:55



Diassemble the "global average temperature" Fred Singer in Wall Street Journal. 5 nov 2011 By Unknown on 5th November, 2011 at 14:07:54
1. Disassemble the "global average temperature" to get a better picture of what's going on regionally. This could involve plotting both the IPCC's and the Berkeley study's data only for tropical regions, separating the northern and southern hemispheres and testing for seasonal variation and differences between day and night.

Posted by Birger Wedendahl By Unknown on 4th November, 2011 at 14:52:54
Birger Wedendahl found this
interesting comment on a blog about BEST

"RC Saumarez says:
5) The assumption behind a mean temperature is that this is a measure of the total energy in the system. It is a construction and a formalisation that does not capture the underlying process and is thermodynamically incorrect unless the system is at equilibrium. As you say, one would ideally have a true mathematical model of the process generating temperature. In this case, one might not even use mean temperature as a description of that model, because the climate is not even in a steady state, and is an intrinsic variable. This reflects what I regard as an important problem: if you write an equation using a variable in a system, you have made an assumption about how the system works, and the way you analyse the data should reflect those assumptions. In other words does the analysis actually make sense in terms of a physical model? "ax
Judith Curry discussing "Hide the Decline" february 2011 in her blog climateetc. By Unknown on 31st October, 2011 at 15:35:11
By Birger Wedendahl
Judith Curry:
"I view paleoclimate as a really important subject in the context of understanding climate change. I have no interest in warmest year or warmest decade; rather we need to understand the magnitude and characteristics and causes of natural climate variability over the current interglacial, particularly the last 2000 years. I’m more interested in the handle than the blade of the hockey stick. I also view understanding regional climate variations as much more important than trying to use some statistical model to create global average anomalies (which I personally regard as pointless, given the sampling issue)."

Posted by Birger Wedendahl
Nobel Price winning physicist Dr.Ivar Gievar: How can you measure the average temperature...... By Unknown on 27th September, 2011 at 10:34:23

Birger Wedendahl

Giaever announced his resignation from APS was due to the group's belief in man-made global warming fears. Giaever explained in his email to APS: "In the APS it is ok to discuss whether the mass of the proton changes over time and how a multi-universe behaves, but the evidence of global warming is incontrovertible? The claim (how can you measure the average temperature of the whole earth for a whole year?) is that the temperature has changed from ~288.0 to ~288.8 degree Kelvin in about 150 years, which (if true) means to me is that the temperature has been amazingly stable, and both human health and happiness have definitely improved in this 'warming' period."

Climate Depot September 2011
Roger Pielke comments on new temperature record by Professor Richard Muller, Berkeley University By Unknown on 3rd April, 2011 at 12:30:19
Global Temperature Trends

the global temperature anomaly is essentially irrelevant in terms of climate change issues that matter to society and the environment. Even in terms of global warming, it is a grossly inadequate measure, as discussed, for example, in

Pielke Sr., R.A., 2003: Heat storage within the Earth system.

Birger Wedendahl

John Christy and Roger Pielke recent comment on global mean temperature.By Birger Wedendahl By Unknown on 9th March, 2011 at 19:00:44
Written Statement of John R. Christy
The University of Alabama in Huntsville
Subcommittee on Energy and Power
Committee on Energy and Commerce
8 March 2011

"The temperature used in this formulation is
nearly always the surface temperature, which is a rather poor metric to serve as a proxy
for the total heat content of the climate system, but that is the convention in use today."

": a focus on metrics that
most directly relate to the rate of accumulation of heat in the climate system (which, for
example, the problematic surface temperature record does not represent),"

Testimony to the Subcommittee on Energy and Power entitled "Climate Science and EPA's Greenhouse Gas Regulation
Roger A. Pielke Sr.
University of Colorado at Boulder and Colorado State University
8 March 2011

"Global Warming is typically defined as an increase in the global average surface temperature. A better metric is the global annual average heat content measured in Joules. Global warming involves the accumulation of heat in Joules within the components of the climate system. This accumulation is dominated by the heating and cooling within the upper layers of the oceans."

"The use of a global annual average surface temperature anomaly as the metric to diagnose global warming is inaccurate and contains significant uncertainties and several systematic biases."

Global average is a tricky business, only a theoretical value. By Unknown on 30th December, 2010 at 23:53:22
Professor Werner Kirstein of the Institute for Geography at the University of Leipzig on MDR German Public Radio.
Professor Kirstein also cautioned against placing too much emphasis on the decade of 2001 -2010 being the hottest decade on record, believing the claim is “a joke” and saying that determining a global average is a tricky business and in the end is only a theoretical value.

Birger Wedendahl
Thanks for intput! By Unknown on 23rd December, 2010 at 09:53:28
Looks interesting!

K.R. Frank Lansner
Current Solar Differences between Northern Hemisphere and Southern Hemisphere By Unknown on 21st December, 2010 at 08:56:58
Since the Sun is off centre in our slightly elliptical orbit the furthest point the Earth was from the Sun in the current orbit I understand was on 7th July 2010 ie Summer in the Northern Hemisphere Winter in the Southern hemisphere. Conversely we are approaching the closest point in the orbit at present which should warm things a little in the Southern hemisphere and give the Northern hemisphere a slightly shorter winter. Look at the graphs for North and South ocean ice cover and you will notice that for the last few years North has been slightly below average for ice cover and South above the median line.
More complications can be viewed in my article on the science of climate change at
Hansen Implies The Arctic Waring is Natural By Unknown on 1st December, 2010 at 10:29:15
Regarding the fact that the Arctic exhibits more warming than the rest of the world, James Hansen said: "Such Arctic warmth could be a natural oscillation … there are few forcings that would yield warmth largely confined to the Arctic. Candidates might be soot blown to the Arctic from industrial activity at the outset of World War II, or solar forcing of the Arctic Oscillation (Shindell et al. 1999; Tourpali et al. 2005) that is not captured by our present model. Perhaps a more likely scenario is an unforced ocean dynamical fluctuation "

Richard Lindzen on global mean temperature By Unknown on 19th November, 2010 at 00:03:26
Richard Lindzens testimony 19.nov 2010

Richard S. Lindzen
Program in Atmospheres, Oceans, and Climate
Massachusetts Institute of Technology
Testimony: House Subcommittee
on Science and Technology hearing on A Rational Discussion of Climate Change: the Science, the Evidence, the Response
November 17, 2010

3. 'Global Warming' refers to an obscure statistical quantity, globally averaged temperature anomaly, the small residue of far larger and mostly uncorrelated local anomalies.

Læs videre her: Citér
Birger Wedendahl: "Global Mean Temperature a Methodological Artefact" By Unknown on 4th May, 2010 at 10:53:07
Perhaps this is the right name for it. According to Methodological Artefact is:

artefacts, statistical and methodological A statistical artefact is an inference that results from bias in the collection or manipulation of data. The implication is that the findings do not reflect the real world but are, rather, an unintended consequence of measurement error. When the findings from a particular study are deemed to be—at least in part—a result of the particular research technique employed (see RESEARCH DESIGN), rather than an accurate representation of the world, they are sometimes said to be a methodological artefact.
4 times A Year, TJ and Paddy. By Unknown on 4th April, 2010 at 14:29:13
GMT is not a temperature for sure. Nobody really can explain to me what it is. Some kind of index? NASA calls it LOTI (Land Ocean Temperature Index), some people think it is a measure for athmospheric inner energy ??? Some says it is a kind of approximation for energybalance???Who knows.
The fact that we cannot calculate a GMT makes it absurd to have a 2 degree target. Nobody is able to find out how fast we are moving towards this "target" and when and where we eventually reach the target.(A vision without a measurable goal is a dream)
Changes in Ocean Heat Content might be a more precise measure but still it will be very difficult to separate how much change is anthropogenic and how much is internal natural variability.

Given the fact we can´t measure GMT we have to accept AMO and PDO and a changing climate.
We simply have to rethink how to measure global warming.
A hot january - but.. By Unknown on 3rd April, 2010 at 00:04:31
Take a look at the prognosis for ENSO. We are facing a La Nina cooling - clashing with the no-good Solar Cycle 24.!3!201003!chart.gif

With all likelyness the flat trend in global temperatures prolonged even beyond the decade of flat temperature trend so far.
So, the more peoble talk about these few hot months, the more the same peoble will respect when temperatures are falling, summer/autumn 2010? ?

K.R. Frank Lansner
4TimesAYear By Unknown on 2nd April, 2010 at 09:27:33
Some time ago it dawned on me that there was no "global" temperature - it was about that time that I realized that the "global average" temperature likewise meant nothing since it won't melt ice anywhere the temp is below freezing. 100° in Chicago won't melt ice in Antarctica or anywhere else. Only actual temps have any meaning. They tell us that we had the warmest January ever this problem - WE DIDN'T HERE IN IOWA - and the "global average" didn't help us either. Don't know when they're going to finally realize - any changes going on are regional or local.
ThomasJ By Unknown on 1st April, 2010 at 23:39:26
The whole 'story' is the biggest, most scoundrand, most deceptive, SCAM in our History - put these fraudslers into Court, á la Nuerenberg..

ThomasJ By Unknown on 1st April, 2010 at 20:57:50
'Global mean temperature'... what an unscientifical definition.. There is NO way to have [GMT] as reference - it's all 'invented' to suit certains purposes. Ie.: put your one foot in warm water and the other in ice-cold water--> so what's the GMT? Or, take T from the Antarctic [-60 C] + put in the T of [let's say] Cotonou [+35 C] and fiddle the GMT out... It's such a devastating scam for..., well everything, science included...
Paddy By Unknown on 1st April, 2010 at 18:43:01
I am sure that one of our eminent climate scientists, Roger Pielke Sr, agrees with these findings. His extensive work has led him to conclude the best metric for global climate in ocean heat content.

Paddy Lenihan, Kirkland, WA (USA)
By Unknown on 1st April, 2010 at 02:25:35
There is also a practical problem with using a nonphysical quantity like "average temperature." There is no physical way to check if you're doing it right.

Heat is physical. In fact, it's a form of energy. Therefore it participates in the conservation of energy. You can check if you've made a stupid mistake in your heat calculations by seeing if the net flow of heat balances the net flow of other forms of energy.

There is no such check for the global average temperature. Given the history, are you willing to take it for granted that there are no stupid mistakes?

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