quote:

Originally posted by TheLastMan:

quote:

The reason why I take the models seriously is that they predict the current warming

But did they predict the warming from the mid-19th century to the mid 20th century when there was little appreciable increase in CO2 levels?

This is the whole point of my argument. The earth has warmed up and cooled down significantly at various times in the 2000 or so years to 1850, a period of static CO2 levels.

So if it wasn't CO2 that was driving that warming and cooling what was it?

If it wasn't CO2, is it possible that the same factors are actually causing the current warming and not CO2?

You seem to have the impression that contemporary climate models take into account only ONE factor, namely, CO2 - and use that to predict temperature. I can understand why you would think this, since we keep seeing graphs in the media showing only these two parameters!

However, climate models actually include a host of parameters known to effect temperature; volcanic activity, solar variation, aerosol pollution etc. So yes, these models DO predict the NATURAL warming trend from the mid-19th to mid-20th century.

This shows up quite clearly in the summary published in the 2001 IPCC report: http://www.grida.no/climate/ipcc_tar/wg1/figspm-4.htm

Note that when you include only natural, or only anthropogenic factors, the model doesn't fit the observed temperature record very well. Whe you include both, the agreement is much closer.

quote:

If there are other factors affecting the warming of the earth's surface, and you cannot quantify or "predict" them for the past ("postdict"?) how can you possibly build and accurate model of the earth's climate that will predict the future?

As I've explained, these factors can be "postdicted", as you put it. If you take into account the period of low global volcanic activity and rising solar activity over this time period, you get a temperature curve which closely fits the observed data.
This shows that the models give quite accurate predictions of the effects of these factors. The important point is that these factors on their own, do NOT predict the current (post 1970s) warming trend.
Only when we include rising greenhouse gas levels in the model does the predicted temperature curve correspond with observation.

quote:

I know people are now questioning the "little ice age" as a localised event. But I simply don't believe this. The effect covered the whole of the continent of Europe. Can you really think that a 150 year period of cooling of a whole continent was not reflected in average global temperatures?

It was - but only slightly. It shows up in the graphs of Mann & his colleges, and other reconstructions. Also, the main evidence for LIA cooling is in Western Europe and the North Atlantic -- a relatively tiny proportion of the earth's surface.

Thanks for the references to the papers on solar energy variation and the Maunder minimum. I have no quarrel with them. But you go on to say:

quote:

This affect is simply not addressed sufficiently in the current climate models. The modellers are going out of their way to try and discredit the TSI affects temperature argument because all the models assume a steady-state input from the sun.

Actually, a number of reconstructions have taken solar brightness into account -- see http://www.ucar.edu/news/releases/2006/brightness.shtml. While solar variation has an effect, the evidence suggests that it is fairly weak. In any case, observations show that various measures of solar activity including the solar flare index, sunspot observations and annual solar irradiance -- which most recently peaked around 2000-2002, are now falling. Meanwhile, temperatures continue to climb. Previous peaks were observed at roughly 11 year intervals, in between which solar activity fell. Clearly, if these variables were the dominant factor driving global warming, we'd expect to see a corresponding pattern of peaks and troughs over the past 30 years -- with no overall tempeature rise.

In summary, climate modellers and the IPCC have never assumed that "all other factors apart from greenhouse gases are static". They have taken other factors into account -- and shown that while they do have significant effects, they are unable, on their own, to explain the current warming trend.

I hope these links etc. are helpful.

GW or not - que sera,sera. Too many people give themselves a self-importance above their station by preaching GW and maybe anti GW too.
Rainforests should be saved for their own sake and likewise precious oil, but until incentives and decent government prevail, things will carry on much as they do today. There is much hope for consumer led demand - it got rid of CFCs and is responsible for the organic food boom for instance. Perhaps it will also produce the fuel cell cars of the future and tidal barrages for electrical production and more... A lot of alternatives put forward as green are anything but, for instance Kyoto targets and windfarms have a probable more damaging environmental impact than not implementing them. How about nuclear? Always condemned as enviro-lunacy (by me as well as others) it now appears that low level radiation may actually be good for you. Did anyone see the documentary on Chernoby wildlife - fit as fiddles, cancer receptors turned on etc. So much from scientific doom merchants arises from bad science or guesswork. If our government wants to be green, why isn't Mr Prescott putting criteria on all the new houses they want to build? Why is bio-fuel even being suggested, and as for so called carbon trading - don't get me started....

Emmet

Do you have a table of stations so I can see where I stand?

Should the forests that covered old England many years ago have been saved?

What should we save the oil for?

What's a decent government (apart from an oxymoron)?

Would consumer demand have got rid of CFC's if there were not alternative propellants for hairspray etc?

The organic food boom I see is a small, ungrowing area in my local supermarket but is it really organic? And if it is what's so good about it? Or is ir that they just haven't made the documentary showing why it's bad for us yet.
..................

The nuclear bit I like as long as it's properly, safely and responsibly managed.

quote:

In summary, climate modellers and the IPCC have never assumed that "all other factors apart from greenhouse gases are static". They have taken other factors into account -- and shown that while they do have significant effects, they are unable, on their own, to explain the current warming trend

Thanks for the comprehensive post. Good to see I can have a discussion with somebody without it turning into a childish slanging match!

I am genuinely willing to be convinced on this, it is just my naturally sceptical nature takes any kind of attempt to model a system as complex as our climate with a large pinch of salt.

I read your first link and all it does is show the output of the model, not the inputs. It actually reinforces my case that the models attribute almost no warming at all to natural forces. The graphs for Natural + CO2 and CO2 only are virtually identical.

I have read in a couple of places the assumptions made in the models for past various natural and anthroprogenic "forcing" factors, the best one is
http://www.giss.nasa.gov/~makis/2006_04+05+06/Fig5a.gif from the Nasa site, a wealth of info there. As you can see there is little forcing attributed to any increase or decrease in solar activity - hence my comment about the models assuming a "steady state" for solar energy. The assumption seems to be that because there is no direct evidence that solar energy has varied significantly in the past therefore we can safely assume that it did not vary. As you will understand, "an absence of evidence is not evidence of absence".

No real attempt has been made to justify this or to attempt to explain warming and cooling in the more distant past at a time of static CO2 levels.

Something must have caused the little ice age. If it wasn't CO2, what was it?
I would genuinely like you to hazard a guess.

This is a question that nobody I have read has convincingly answered. Everybody simply tries to deny that it happened at all or (rather unconvincingly) that it was somehow a minor event.

Although now "contaminated" by fossil fuel combustion, the C14 record seems to show a long term rise in solar radiation that has not been taken into account in "postdictions" of warming in the recent past.
http://en.wikipedia.org/wiki/Image:Carbon-14_with_activity_labels.png

It also shows a global reduction in C14 associated with the Maunder minimum, which again suggests that the global cooling might have extended to more of the globe than you suggest.

Second attempt!

http://www.giss.nasa.gov/~makis/2006_04+05+06/Fig5a.gif

Third attempt!

http://www.giss.nasa.gov/~makis/transient/simFig5.pdf

If this doesn't work, the paper it is from is
http://www.giss.nasa.gov/~makis/transient/

And if that doesn't work, I give up!

I have been trying to find a reasobale argument for the following -

AGW 1910 to 1940 saw a rise of 0.5dgC
AGW 1980 to 2004 saw a rise of 0.5dgC

The second period has been given 90/95% chance of being induced by man made co2

The first period rise has no known cause. A variety of explantions are available for the first rise - none of them have any scinetific proof. The second rise seems to certainly be caused by co2. How can one square these two contradictory arguments. Isnt it just as likely that whatever caused the 1910 to 1940 rise also is causing the 1980 to 2010 rise??

quote:

Originally posted by Roger58:
BTW: I didn't mean to be mean to TheHeretic - just wondering if he is aware of how paradoxically Conformist he is in his views. Still, I guess he's young, so why not?

Hi Roger58,

Thanks, but I'm afraid I'm not all that young. You label me "conformist" simply because on a particular issue, I happen to agree with the consensus view amongst scientists in that field (and indeed, most other scientists who are aware of facts).

But that would only be conformism if I'd accepted this without look at the evidence and the arguments on both sides, before making up my mind.

The suggestion that I haven't is, frankly, insulting. Not that you'd know, but on some other scientific issues which interest me, my views are far from conventional... but that's not really the point at issue.

Incidentally, it was the Christian church who first used the word Heretic to mean someone who challenges orthodoxy (whatever that happens to be). The word comes from the Ancient Greek 'eiretikos' meaning (roughly) thinking for oneself, or thinking indepedently -- and that in that sense, I feel I'm justified in considering myself a "heretic".

This does not necessarily mean ALWAYS rejecting the most commonly held, or most "authoritative" view. It just means looking at important questions from all angles - taking into account multiple points of view - and doing your best to work out which arguments are closest to the truth.

Nobody's immune to bias, of course -- but it's too easy to label someone who argues a position you disagree with as just slavishly conforming to a dogma. Especially when you're unable to come up with a better argument yourself.

The fuss over one inaccurate graph (which most certainly was NOT the core element of the program as some have stated ) does tend to obscure other important observations such as the absence of higher temperatures in the troposphere that you'd expect from CO2 based warming, or the observation that in longer term temperature scales the heat increase appears to occur some 800 years or so ahead of any proportional rise in CO2......which of course suggests that the warming is causing the CO2 rise and not the other way round.

But to my mind, in this program I was more interested not in graphs or direct data but in the fact that concensus on CO2 warming is not absolute. There are clearly scientists doing what scientists SHOULD do............question the entire premise of scientific theory. That, rather than the somewhat hysterical ' oh my God....they questioned CO2 related warming !' evinced by some, is what proper science is all about.

quote:

Originally posted by Chi Squared:
... the observation that in longer term temperature scales the heat increase appears to occur some 800 years or so ahead of any proportional rise in CO2......which of course suggests that the warming is causing the CO2 rise and not the other way round.

Thanks Chi Squared for your post. I am looking for a convincing explaination from the AGW folks for the lag in CO2 rise vs warming. This element of surprise from the ice core samples needs to be dealt with. For example, what could have happened 800 years ago that could have possibly started the current CO2 rise? How much of the current CO2 elevation is man-made? Most important, since CO2 consentration is so miniscule, what effect does it really have on our climate? Weather models predict that CO2 warming would be greater at the 10 km altitude vs ground temperatures. This is not the measured reality.

For the record, I am a heretic.

quote:

Originally posted by TheLastMan:
Thanks for the comprehensive post. Good to see I can have a discussion with somebody without it turning into a childish slanging match!

I read your first link and all it does is show the output of the model, not the inputs. It actually reinforces my case that the models attribute almost no warming at all to natural forces. The graphs for Natural + CO2 and CO2 only are virtually identical.

Thanks - you seem to be one of the few skeptics in this forum who is actually skeptical in the proper sense of the word! (I believe Aristotle used 'skepteion' to mean something like "this should be investigated").

On your first point - agreed; I'd like to know exactly what factors are taken into account as "natural" forcings. Probably buried somewhere else in the IPCC report... also, I expect there's a lot more data coming out in the full 2007 report, which is due out soon.

On the second point - they do differ. The "anthropogenic only" graph *underestimates* the observed temperature record during a period from around 1930 to 1950; if you look at the "natural only" graph, the fit during this period is quite good. So it looks as if, during this period, the natural forcings are dominant. After about 1970, the "natural only graph underestimtes the recent temperature rise, suggesting that in this period, anthropogenic factors have become dominant.

Of course, without a detailed breakdown of inputs, we can speculate that not all of the possibly relevant natural factors have been included in the model. However, if that was the case, it seems highly unlikely to me that the "natural+anthropogenic graph would so such a close fit to the observed temperature curve, all the way from 1860 to 2000. This gives us no reason to think that any significant natural forcings have been left out.

quote:

I have read in a couple of places the assumptions made in the models for past various natural and anthroprogenic "forcing" factors, the best one is
http://www.giss.nasa.gov/~makis/2006_04+05+06/Fig5a.gif from the Nasa site, a wealth of info there. As you can see there is little forcing attributed to any increase or decrease in solar activity - hence my comment about the models assuming a "steady state" for solar energy. The assumption seems to be that because there is no direct evidence that solar energy has varied significantly in the past therefore we can safely assume that it did not vary. As you will understand, "an absence of evidence is not evidence of absence".

I think you've overlooked figure 4. As you can see, they don't assume a constant figure for total solar irradiance; they use actual observations.

http://www.giss.nasa.gov/%7Emakis/transient/simFig4.pdf

As you can see in this graph, TSI varies considerably - and not only in the familiar, 11-year sunspot cycle. We see a period from 1880 to 1920 when the TSI is low, varying between 1364.5 and 1365.5 W/m^2. Then there's a change as the curve climbs upward -- and from 1960 onwards, it's varying about a new mean of around 1366.5. However, after 1960, the curve doesnt noticably climb any higher.

This suggests that while the rise in mean TSI from 1920 to 1960 may have played a part in raising temperatures during that time, there is no rise in mean TSI since 1960 which would account for the temperature rise since then, if TSI were the dominant factor

quote:

Something must have caused the little ice age. If it wasn't CO2, what was it?
I would genuinely like you to hazard a guess.

This is a question that nobody I have read has convincingly answered. Everybody simply tries to deny that it happened at all or (rather unconvincingly) that it was somehow a minor event.

I don't think it was a minor event - the contempory European and Northern American accounts make it clear, it was bloody cold!

The causes of past climate changes are difficult to with any certainty; not all of the relevant variables can reconstructed from ice-cores or tree-rings and the like. However, I suspect that it was a combination of factors.

The low TSI seems to be a likely factor; another is that throughout the LIA, there was a great deal of volcanic activity. Ash and sulphur dioxide from volcanos have a well-established cooling effect. As you may know, The "super-colossal" eruption of Mout Tambora (in Indonesia) in 1815 was the most powerful in recorded history; bringing about the infamous "year without a Summer" in 1816.

These might have triggered other secondary factors which are thought to have played some role, including changes in atmospheric circulation and possibly, ocean currents. These factors could explain why it seems to have been a lot colder in some places than others.

The following excert from the 2001 IPCC report may shed some light:

[QUOTE/] 2.3.3 Was there a “Little Ice Age” and a “Medieval Warm Period”?

The terms “Little Ice Age” and “Medieval Warm Period” have been used to describe two past climate epochs in Europe and neighbouring regions during roughly the 17th to 19th and 11th to 14th centuries, respectively. The timing, however, of these cold and warm periods has recently been demonstrated to vary geographically over the globe in a considerable way (Bradley and Jones, 1993; Hughes and Diaz, 1994; Crowley and Lowery, 2000). Evidence from mountain glaciers does suggest increased glaciation in a number of widely spread regions outside Europe prior to the 20th century, including Alaska, New Zealand and Patagonia (Grove and Switsur, 1994). However, the timing of maximum glacial advances in these regions differs considerably, suggesting that they may represent largely independent regional climate changes, not a globally-synchronous increased glaciation (see Bradley, 1999). Thus current evidence does not support globally synchronous periods of anomalous cold or warmth over this timeframe, and the conventional terms of “Little Ice Age” and “Medieval Warm Period” appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries. With the more widespread proxy data and multi-proxy reconstructions of temperature change now available, the spatial and temporal character of these putative climate epochs can be reassessed.

Mann et al. (1998) and Jones et al. (1998) support the idea that the 15th to 19th centuries were the coldest of the millennium over the Northern Hemisphere overall. However, viewed hemispherically, the “Little Ice Age” can only be considered as a modest cooling of the Northern Hemisphere during this period of less than 1°C relative to late 20th century levels (Bradley and Jones, 1993; Jones et al., 1998; Mann et al., 1998; 1999; Crowley and Lowery, 2000). Cold conditions appear, however, to have been considerably more pronounced in particular regions. Such regional variability can be understood in part as reflecting accompanying changes in atmospheric circulation. The “Little Ice Age” appears to have been most clearly expressed in the North Atlantic region as altered patterns of atmospheric circulation (O’Brien et al., 1995). Unusually cold, dry winters in central Europe (e.g., 1 to 2°C below normal during the late 17th century) were very likely to have been associated with more frequent flows of continental air from the north-east (Wanner et al., 1995; Pfister, 1999). Such conditions are consistent (Luterbacher et al., 1999) with the negative or enhanced easterly wind phase of the NAO (Sections 2.2.2.3 and 2.6.5), which implies both warm and cold anomalies over different regions in the North Atlantic sector. Such strong influences on European temperature demonstrate the difficulty in extrapolating the sparse early information about European climate change to the hemispheric, let alone global, scale. While past changes in the NAO have likely had an influence in eastern North America, changes in the El Niño phenomenon (see also Section 2.6), are likely to have had a particularly significant influence on regional temperature patterns over North America.

The hemispherically averaged coldness of the 17th century largely reflected cold conditions in Eurasia, while cold hemispheric conditions in the 19th century were more associated with cold conditions in North America (Jones et al., 1998; Mann et al., 2000b). So, while the coldest decades of the 19th century appear to have been approximately 0.6 to 0.7°C colder than the latter decades of the 20th century in the hemispheric mean (Mann et al., 1998), the coldest decades for the North American continent were closer to 1.5°C colder (Mann et al., 2000b). In addition, the timing of peak coldness was often specific to particular seasons. In Switzerland, for example, the first particularly cold winters appear to have been in the 1560s, with cold springs beginning around 1568, and with 1573 the first unusually cold summer (Pfister, 1995).

The evidence for temperature changes in past centuries in the Southern Hemisphere is quite sparse. What evidence is available at the hemispheric scale for summer (Jones et al., 1998) and annual mean conditions (Mann et al., 2000b) suggests markedly different behaviour from the Northern Hemisphere. The only obvious similarity is the unprecedented warmth of the late 20th century. Speleothem evidence (isotopic evidence from calcite deposition in stalagmites and stalactites) from South Africa indicates anomalously cold conditions only prior to the 19th century, while speleothem (records derived from analysing stalagmites and stalagtites) and glacier evidence from the Southern Alps of New Zealand suggests cold conditions during the mid-17th and mid-19th centuries (Salinger, 1995). Dendroclimatic evidence from nearby Tasmania (Cook et al., 2000) shows no evidence of unusual coldness at these times. Differences in the seasons most represented by this proxy information prevent a more direct comparison.

As with the “Little Ice Age”, the posited “Medieval Warm Period” appears to have been less distinct, more moderate in amplitude, and somewhat different in timing at the hemispheric scale than is typically inferred for the conventionally-defined European epoch. The Northern Hemisphere mean temperature estimates of Jones et al. (1998), Mann et al. (1999), and Crowley and Lowery (2000) show temperatures from the 11th to 14th centuries to be about 0.2°C warmer than those from the 15th to 19th centuries, but rather below mid-20th century temperatures. The long-term hemispheric trend is best described as a modest and irregular cooling from AD 1000 to around 1850 to 1900, followed by an abrupt 20th century warming. Regional evidence is, however, quite variable. Crowley and Lowery (2000) show that western Greenland exhibited anomalous warmth locally only around AD 1000 (and to a lesser extent, around AD 1400), with quite cold conditions during the latter part of the 11th century, while Scandinavian summer temperatures appeared relatively warm only during the 11th and early 12th centuries. Crowley and Lowery (2000) find no evidence for warmth in the tropics. Regional evidence for medieval warmth elsewhere in the Northern Hemisphere is so variable that eastern, yet not western, China appears to have been warm by 20th century standards from the 9th to 13th centuries. The 12th and 14th centuries appear to have been mainly cold in China (Wang et al., 1998a,b; Wang and Gong, 2000). The restricted evidence from the Southern Hemisphere, e.g., the Tasmanian tree-ring temperature reconstruction of Cook et al. (1999), shows no evidence for a distinct Medieval Warm Period.

Medieval warmth appears, in large part, to have been restricted to areas in and neighbouring the North Atlantic. This may implicate the role of ocean circulation-related climate variability. The Bermuda rise sediment record of Keigwin (1996) suggests warm medieval conditions and cold 17th to 19th century conditions in the Sargasso Sea of the tropical North Atlantic. A sediment record just south of Newfoundland (Keigwin and Pickart, 1999), in contrast, indicates cold medieval and warm 16th to 19th century upper ocean temperatures. Keigwin and Pickart (1999) suggest that these temperature contrasts were associated with changes in ocean currents in the North Atlantic. They argue that the “Little Ice Age” and “Medieval Warm Period” in the Atlantic region may in large measure reflect century-scale changes in the North Atlantic Oscillation (see Section 2.6). Such regional changes in oceanic and atmospheric processes, which are also relevant to the natural variability of the climate on millennial and longer time-scales (see Section 2.4.2), are greatly diminished or absent in their influence on hemispheric or global mean temperatures.[/QUOTE]

From: http://www.grida.no/climate/ipcc_tar/wg1/070.htm

I would not call myself a heretic or a believer. Science is about evidence, not what people personally happen to believe. Thus, for example, I don't 'believe' in life on other planets but it's not a belief but a sound observation that there is not one single scrap of evidence to support it ! That does not rule out the possibility that there could be, but until evidence exists I fail to see that 'belief' makes a blind bit of difference.

Similarly, athough nobody has ever seen a black hole, there is massive evidence that they exist.

I just don't see that that sort of level of evidence exists for CO2 based warming. At least not yet. It's at about the same level as evidence that an asteroid wiped out the dinosaurs.......which is hotly contested by sceptics who point out a host of inconsistencies in the theory.

In fact the analogy with the dinosaur theory is a good one, as the entire thing has entered popular culture and no end of National Geographic documentaries ( and even TV adverts ). Ask anyone, and they will tell you that an asteroid wiped out the dinosaurs.....'scientists say so'. All of which overlooks the fact that a lot of scientists don't say so and some flaty refute the theory altogether.

I'm very impressed with your explanations Heritic.

The one thing that annoyed me about the documentary was the strawman that client scientists ignored natural factors. They did not; they were a fundamental part of explaining how today's warming is man made.

Somebody here also mentioned the "time lag" between temperature changes and CO2 concentrations. I believe this is because when the sea heats up (which takes time), it releases CO2. So CO2 rises have often followed a temperature increase in the past. This creates a "positive feedback" in that the more CO2 we pump in, we could find the sea releasing even more. What a comforting thought.

quote:

Originally posted by real scientist:
I'm very impressed with your explanations Heritic.

The one thing that annoyed me about the documentary was the strawman that client scientists ignored natural factors. They did not; they were a fundamental part of explaining how today's warming is man made.

Somebody here also mentioned the "time lag" between temperature changes and CO2 concentrations. I believe this is because when the sea heats up (which takes time), it releases CO2. So CO2 rises have often followed a temperature increase in the past. This creates a "positive feedback" in that the more CO2 we pump in, we could find the sea releasing even more. What a comforting thought.

Ok, lets say that last part you said is true.... why doesn't it reflect in the graph? There is an up swing that follows the temp, and then a down swing that follows the temp. If what you are saying has any merit, then the rise should continue to rise, except it doesn't, it would appear to me that another outside influence is affecting temperature and thus affecting CO2. So whats the deal? History doesn't seem to follow your logic.

Oh and I am by no means a scientist. I just enjoy reading and questioning the 'norm' as it where. When things don't seem to fit, I have to question them until they make sense.

Just commenting on the Little Ice Age, the fact that there was a good deal of local and hemispheric variation does not prove that there was not a global cause. Even within current models of global warming, there is widespread variation locally and between continents. Also, the southern hemisphere is 90% ocean so you'd expect any short lived ( i.e a few hundred years ) effect to be more counterbalanced by residual ocean heat.

It does seem curious that the LIA corresponded so closely with the Maunder minimum of sunspot activity. There's little doubt that solar activity does affect the atmosphere in a number of ways. A strong solar CME ( coronal mass ejection ) actually compresses the atmosphere a little ( as well as stripping away some of it ! ).

I'm not entirely sure I buy the idea that CMEs are knocking cosmic rays off course. That is not actually what's happening, and is an area where the documentary is factually a little incorrect. Cosmic rays are largely protons and neutrons, travelling at very high speed ( close to the speed of light ). The density of the average CME is maybe 10 protons per cubic cm travelling at about a million miles per hour ( i.e several thousand times slower ). CME protons don't stand a chance against cosmic rays. Also.....protons are much smaller than entire atoms and the chances of collisions are minimal.....otherwise the cosmic rays would themselves be cancelling each other out as they come from all directions.

It is actually the sun's magnetic field ( not CME's ) that causes the effect of holding back cosmic rays ....as it gets in a twist during solar maximum which allows in more charged particles from space. The effect is the same......but I do think the documentary should have given the correct explanation.

quote:

Originally posted by Chi Squared:
The fuss over one inaccurate graph (which most certainly was NOT the core element of the program as some have stated ) does tend to obscure other important observations such as the absence of higher temperatures in the troposphere that you'd expect from CO2 based warming, or the observation that in longer term temperature scales the heat increase appears to occur some 800 years or so ahead of any proportional rise in CO2......which of course suggests that the warming is causing the CO2 rise and not the other way round.

Actually there were several inaccurate, misleading graphs - but let me answer your questions.

First - the troposphere stuff. This was based on a 2003 paper by Dr John Christy, who was interviewed in the programme. His studies of a weather balloon and satellite data did indeed reveal a puzzle -- the troposphere didn't seem to be getting warmer. Standard thermodynamics predicts that given the increase in surface temperature (which no-one doubted), the troposphere should be getting warmer too; indeed, in the tropics it should warm *faster* than the surface.

Its wildly illogical to take this evidence as an argument against anthropogenic global warming -- as Christy did in his interview. WHATEVER is warming the surface, be it an increasing greenhouse effect or Martin Durkin's pants on fire, the troposphere should be warming too!

Subsequently, errors were discovered in the satellite and weather balloon data -- and when this were allowed for, the data fitted the theory. (The theory of thermodynamics, that is). In his interview, Christy seems to have fogotten the fact that he has admitted this himself -- in the executive summary to the
US Climate Change Science Program report, which CHRISTY HIMSELF AUTHORED:

quote:

Previously reported discrepancies between the amount of warming near the surface and higher in the atmosphere have been used to challenge the reliability of climate models and the reality of human induced global warming. Specifically, surface data showed substantial global-average warming, while early versions of satellite and radiosonde data showed little or no warming above the surface. This significant discrepancy no longer exists because errors in the satellite and radiosonde data have been identified and corrected. New data sets have also been developed that do not show such discrepancies.

Second: the temperature CO2 time-lag in the ice-cores showed that at the transitions between ice-ages and interglacial warm periods, there is a rise in C02 - about 800 years after it starts to get warmer.

This shows that something else must cause the onset of an interglacial period. We know what that cause is - its called the Milankovich cycle. A combination of periodic changes in the eccentricity of the earth's orbit, its angle of tilt on its axis etc - resulting in more effective solar radiation. Thats what gets the interglacial period going -- which stimulates life to flourish; natural CO2 is released into the atmosphere, AMPLIFYING the warming effect.

Thus, the 800 year time-lag doesnt prove that CO2 can't ever cause global warming. It just shows that when it comes to ice ages, its not the only factor.

quote:

But to my mind, in this program I was more interested not in graphs or direct data but in the fact that concensus on CO2 warming is not absolute. There are clearly scientists doing what scientists SHOULD do.. question the entire premise of scientific theory. That, rather than the somewhat hysterical ' oh my God....they questioned CO2 related warming !' evinced by some, is what proper science is all about.

It's great when scientists question established theory - when they do so with really good arguments. Witness, Copernicus, Galileo, Einstein. However, just the fact of rejecting a widely accepted theory doesn't necessarily elevate a scientist into that company.

On any contempory scientific question, you'll never get absolute consensus. However, when those who disagree with the consenus can only produce obsolete or erroneous data, dodgy graphs and logically fallacious arguments -- and when most of the dissenters, moreover, are up to their necks in vested interests -- this doesn't seem a good reason for doubting the consensus view.

Another great explanation from Heritic.