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"The main gas producing the green house effect is water vapour.", I think that he means that the concentration of water vapor in air is so much higher (than the other compounds that contribute to the warming) that the total heat contribution is higher for the water vapor. Problem with that is that water vapor in the atmosphere is always substantial. Of course, it varies, but a rise in the concentration is generally a result of, before it becomes a contributor to, increased temperature.

So - the root cause of global warming is increases of concentration in other molecules. Clearly, concentrations of CO2, NOx, and sulfate ions in the atmosphere have been on the rise since not-long-after the start of industrial development. CO2 shows the largest increase - for obvious reasons, since the main energy sources have been combustion of hydrocarbons - and, in fact, there is significant correlation between the rise in CO2 levels and the rise in temperature, using reasonable estimates of the data.

After temperatures rise, other factors, such as methane release from previously-frozen Siberian bogs, become significant factors. Also, once glaciers melt, the exposed ground absorbs heat that the glaciers tend to reflect. These kinds of thresholds are almost irreversible, once started. So - we have to work on the factors that we can control. The Professor isn't helping in that regard, when he makes statements in a popular journal that undermine action concerning CO2 reduction.

paul spencer

by paul spencer (spencerinthegorge AT yahoo DOT com) on Thu Jan 24th, 2008 at 03:55:26 PM EST
On H2O I recommend this short article by Ahilleas Maurellis:

The climatic effects of water vapour.

--


Clearly, concentrations of CO2, [...] in the atmosphere have been on the rise since not-long-after the start of industrial development.

Could you substantiate this with a reference? Are you basing that assertion on proxy data or direct measurements?

You might find me At The Edge Of Time.

by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 09:59:53 AM EST
[ Parent ]
TRENDS: ATMOSPHERIC CARBON DIOXIDE
An atmospheric CO2 record for the past 200 years was obtained from the Siple Station ice core.

...

Neftel et al. (1985) concluded that the atmospheric CO2 concentration ca. 1750 was 280±5 parts per million by volume (ppmv) and that it increased by 22.5% to 345 ppmv in 1984 essentially because of human factors. Graphs in Friedli et al. (1986) also reported that the preindustrial (pre-1800) CO2 concentration was ~280 ppmv.

There are also charts from other ice core measurements:


We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 10:16:44 AM EST
[ Parent ]
No direct measurements?

A different result from a different proxy:

Kouwenberg, L, Wagner, R, Kurschner, W and Visscher H, 2005. Atmospheric CO2 fluctuations during the last millenium reconstructed by stomatal frequency analysis of Tsuga heterophylla needles, Geology, 33: 33-36.

You might find me At The Edge Of Time.

by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 10:54:27 AM EST
[ Parent ]
Of course there are no direct measurements. There was not a lot of direct measurement of atmospheric composition before the 19th century, was there?

Oh, and measuring the concentration of gases trapped in ice is a better proxy than growth rates of organisms.

We have met the enemy, and he is us — Pogo

by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 10:59:25 AM EST
[ Parent ]

Oh, and measuring the concentration of gases trapped in ice is a better proxy than growth rates of organisms.

That's a highly disputable assertion. Do you know the work of Zbigniew Jaworowski? You'll understand the 83 year joke there.


There was not a lot of direct measurement of atmospheric composition before the 19th century, was there?

But you are aware that the measurements made from the XIX onwards do not match the ice proxies, don't you?


You might find me At The Edge Of Time.

by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 11:19:21 AM EST
[ Parent ]
"But you are aware that the measurements made from the XIX onwards do not match the ice proxies, don't you?"

paul spencer
by paul spencer (spencerinthegorge AT yahoo DOT com) on Mon Jan 28th, 2008 at 11:28:15 AM EST
[ Parent ]
Zbigniew Jaworowski - Wikipedia, the free encyclopedia

Jaworowski is a global warming skeptic.

His works on ice cores were published in Jaworowski (1994, 1992) and in reports Jaworowski (1990, 1992).

Jaworowski has suggested that the long-term CO2 record is an artifact caused by the structural changes of the ice with depth and by postcoring processes. However, increases in CO2 and CH4 concentrations in the Vostok core are similar for the last two glacial-interglacial transitions, even though only the most recent transition is located in the brittle zone. Such evidence argues that the atmospheric trace-gas signal is not strongly affected by the presence of the brittle zone. [1]

Similarly Hans Oeschger [2] states that "...Some of (Jaworowski's) statements are drastically wrong from the physical point of view".

Who is Hans Oeschger?

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 11:30:38 AM EST
[ Parent ]
This is the PDF linked from the foornote in the wikipedia article:

If I understand the issue correctly, Oetscher is claiming that diffusion of gas in firn explains the 83-year shift.

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 11:47:15 AM EST
[ Parent ]
This is Jaworowski's Key Claim.

Zbigniew Jaworowski on CO2 measurements

The data from shallow ice cores, such as those from Siple, Antarctica[5, 6], are widely used as a proof of man-made increase of CO2 content in the global atmosphere, notably by IPCC[7]. These data show a clear inverse correlation between the decreasing CO2 concentrations, and the load-pressure increasing with depth (Figure 1 A) . The problem with Siple data (and with other shallow cores) is that the CO2 concentration found in pre-industrial ice from a depth of 68 meters (i.e. above the depth of clathrate formation) was "too high". This ice was deposited in 1890 AD, and the CO2 concentration was 328 ppmv, not about 290 ppmv, as needed by man-made warming hypothesis. The CO2 atmospheric concentration of about 328 ppmv was measured at Mauna Loa, Hawaii as later as in 1973[8], i.e. 83 years after the ice was deposited at Siple.

An ad hoc assumption, not supported by any factual evidence[3, 9], solved the problem: the average age of air was arbitrary decreed to be exactly 83 years younger than the ice in which it was trapped. The "corrected" ice data were then smoothly aligned with the Mauna Loa record (Figure 1 B) , and reproduced in countless publications as a famous "Siple curve". Only thirteen years later, in 1993, glaciologists attempted to prove experimentally the "age assumption"[10], but they failed[9].

...

3. Jaworowski, Z., T.V. Segalstad, and N. Ono, Do glaciers tell a true atmospheric CO2 story? The Science of the Total Environment, 1992. 114: p. 227-284.

...

  1. Jaworowski, Z., Ancient atmosphere - validity of ice records. Environ. Sci. & Pollut. Res., 1994. 1(3): p. 161-171.

  2. Schwander, J., et al., The age of the air in the firn and the ice at Summit, Greenland. J. Geophys. Res., 1993. 98(D2): p. 2831-2838.


We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 11:52:24 AM EST
[ Parent ]
Note the 1994 paper is the one Oeschger's rebuttal refers to.

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 11:54:44 AM EST
[ Parent ]
Miguel I have to leave now. This is a fascinating issue, we'll have to get back again to it some day.

You might find me At The Edge Of Time.
by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 12:51:27 PM EST
[ Parent ]
The entire letter by Oescher is transcribed as HTML in the blog Some are Boojums:
Hans Oeschger's letter to ESPR
Jaworowski's article in ESPR is so hard to locate, it wouldn't be too unreasonable to suspect that the journal is not eager now for people to take much notice of it. But it did get noticed by one giant in climate science -- Hans Oeschger.
Prof. Oeschger was the founder of the Division of Climate and Environmental Physics at the Physics Institute of the University of Bern. His name is attached to the Oeschger Counter that enabled Carbon-14 dating to be applied to geophysical problems, and to the Dansgaard-Oeschger 1,500 year cycle of slow cooling and abrupt warming observed in sediments and ice cores. He was active and influential in climate science until his death in 1998. His assessment of the Jaworowski article was blunt.


We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 05:27:46 PM EST
[ Parent ]
This comment is strange. The work I know from Jaworowski concentrates on near-range proxy data.

You might find me At The Edge Of Time.
by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 11:49:31 AM EST
[ Parent ]
Direct measurements started after WWII, in Hawaii. They showed an increasing trend, immediately. They do match recent ice cores, to my knowledge.

Pierre
by Pierre on Mon Jan 28th, 2008 at 11:37:20 AM EST
[ Parent ]
Lazy link:


Pierre
by Pierre on Mon Jan 28th, 2008 at 11:42:32 AM EST
[ Parent ]
That's one data set. There are dozens more that report to previous periods.

You might find me At The Edge Of Time.
by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 12:49:18 PM EST
[ Parent ]
Direct CO2 atmospheric concentration measurements have been made since the early XIX century. Did you check Joworowski's article?

The ice core data matches Maona Loa only after the 83 year shift.

You might find me At The Edge Of Time.

by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 11:45:29 AM EST
[ Parent ]
Direct CO2 atmospheric concentration measurements have been made since the early XIX century.

Not meaningfully, according to

URS SIEGENTHALER, ERIC MONNIN, KENJI KAWAMURA, RENATO SPAHNI, JAKOB SCHWANDER, BERNHARD STAUFFER, THOMAS F. STOCKER, JEAN-MARC BARNOLA, HUBERTUS FISCHER (2005)
Supporting evidence from the EPICA Dronning Maud Land ice core for atmospheric CO2 changes during the past millennium
Tellus B 57 (1), 51-57.
In particular, from the abstract
The most direct method of investigating past variations of the atmospheric CO2 concentration before 1958, when continuous direct atmospheric CO2 measurements started, is the analysis of air extracted from suitable ice cores.
(my emphasis)

The abstract continues:

Here we present a new detailed CO2 record from the Dronning Maud Land (DML) ice core, drilled in the framework of the European Project for Ice Coring in Antarctica (EPICA) and some new measurements on a previously drilled ice core from the South Pole. The DML CO2 record shows an increase from about 278 to 282 parts per million by volume (ppmv) between ad 1000 and ad 1200 and a fairly continuous decrease to a mean value of about 277 ppmv around ad 1700. While the new South Pole measurements agree well with DML at the minimum at ad 1700 they are on average about 2 ppmv lower during the period ad 1000-1500. Published measurements from the coastal high-accumulation site Law Dome are considered as very reliable because of the reproducibility of the measurements, high temporal resolution and an accurate time scale. Other Antarctic ice cores could not, or only partly, reproduce the pre-industrial measurements from Law Dome. A comparison of the trends of DML and Law Dome shows a general agreement. However we should be able to rule out co-variations caused by the same artefact. Two possible effects are discussed, first production of CO2 by chemical reactions and second diffusion of dissolved air through the ice matrix into the bubbles. While the first effect cannot be totally excluded, comparison of the Law Dome and DML record shows that dissolved air diffusing to bubbles cannot be responsible for the pre-industrial variation. Therefore, the new record is not a proof of the Law Dome results but the first very strong support from an ice core of the Antarctic plateau.


We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 05:54:00 PM EST
[ Parent ]
BTW, that 83 year constant shift is really hard to explain ;-)

You might find me At The Edge Of Time.
by Luis de Sousa (luis[dot]a[dot]de[dot]sousa[at]gmail[dot]com) on Mon Jan 28th, 2008 at 10:56:24 AM EST
[ Parent ]
Huh?

We have met the enemy, and he is us — Pogo
by Migeru (migeru at eurotrib dot com) on Mon Jan 28th, 2008 at 11:00:32 AM EST
[ Parent ]
The data is, in fact, out there via core-drilled ice readings, but I'm not going to bother any more than your jubilated professor backs up any of his statements in the quoted interview.

paul spencer
by paul spencer (spencerinthegorge AT yahoo DOT com) on Mon Jan 28th, 2008 at 11:19:15 AM EST
[ Parent ]

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