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Posted
  • Location: Sunny Southsea
  • Location: Sunny Southsea

C-Bob: there are a range of potentially useful articles here: http://www.clim-past.net/recent_papers.html

The Zeng paper is interesting - but it is only a hypothesis at the moment, and the Hargreaves et. al. paper deals with climate sensitivity experiments for the LGM: that's the best I can do for the moment. in the latter paper, I think it says that 2xCO2 causes +3.62W/M2. Only a small proportion of the rises you chart, then, are atrributable to CO2. Other forcings in the paper include Milankovitch variations (insolation changes), Ice sheets (and ice sheet ablation), Methane and something else I can't remember.

I think a recent paper by Hansen et. al. gives similar figures; I'll look for it.

Senior ridge; you're joking, right?

:)P

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey

Okay, here's another one to be thinking about while I'm looking through P3's link (Good link, by the way ;) )

How quickly should temperature respond to the assumed forcing from CO2? There should be a response in the short term, which would become compounded in the long term. Let's look at the official graphs of temperature (taken from Wiki - I think it originally comes from GISS), and CO2 (from GRIDA).

post-6357-1175254751_thumb.png

post-6357-1175254678_thumb.jpg

The CO2 graph shows the recognisable (and expected) non-linear trend, yet the temperature graph shows a linear trend (with the thirty year dip between around 1940 and 1970). Furthermore, despite significantly higher CO2 concentrations in the latter half of the 20th Century, and a longer history of increased CO2 concentrations, the plot of warming post-1970 has a virtually identical gradient to that of the warming up to 1940:

post-6357-1175254997_thumb.jpg

Looking at the "Solar Influence" argument, here's a graph taken from Global Warming Art of Solar Activity between 1400 and 2000 - note the period of the graph between 1900 and 2000:

post-6357-1175254688_thumb.png

Now, I'm not going to even suggest that this "Drives the Final Nail into the Coffin of AGW" or anything, and I don't dispute that CO2 may have some effect (I should make that sentence a part of my signature!), but it is interesting to me that the Solar Activity graph shows a fairly linear trend over the relevant time period where the CO2 graph does not (yes, sunspot number does level off, but sunspots are not the only indicator of solar activity and, though it does not continue all the way to 2000, 10Be Concentration continues to rise after sunspot number levels off). Obviously something happened between 1940 and 1970 to cause the "blip" in the graph, but let's ignore that for now ;)

The obvious argument to counter this is that solar forcing is not sufficiently powerful enough to account for the observed warming trend, but CO2 forcing is. But is the magnitude of the CO2 increase actually a good fit for the temperature increase?

Why does this not work for me? :unknw:

CB

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Posted
  • Location: Sunny Southsea
  • Location: Sunny Southsea

Keeping just on the 'Solar influence' matter for the moment, this is an up-to-date. I don't have access to the full paper:

GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L05713, doi:10.1029/2006GL028356, 2007

20th century changes in surface solar irradiance in simulations and observations

A. Romanou

Department of Applied Physics and Mathematics, Columbia University, New York, New York, USA

B. Liepert

Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA

G. A. Schmidt

NASA Goddard Institute for Space Studies, New York, New York, USA

W. B. Rossow

NASA Goddard Institute for Space Studies, New York, New York, USA

R. A. Ruedy

Sigma Space Partners, New York, New York, USA

Y. Zhang

Department of Applied Physics and Mathematics, Columbia University, New York, New York, USA

Abstract

The amount of solar irradiance reaching the surface is a key parameter in the hydrological and energy cycles of the Earth's climate. We analyze 20th Century simulations using nine state-of-the-art climate models and show that all models estimate a global annual mean reduction in downward surface solar radiation of 1–4 W/m2 at the same time that the globe warms by 0.4–0.7°C. In single forcing simulations using the GISS-ER model, this “global dimming” signal is shown to be predominantly related to aerosol effects. In the global mean sense the surface adjusts to changes in downward solar flux instantaneously by reducing the upward fluxes of longwave, latent and sensible heat. Adding increased greenhouse gas forcing traps outgoing longwave radiation in the atmosphere and surface which results in net heating (although reduced) that is consistent with global warming over the 20th Century. Over the 1984–2000 period, individual model simulations show widely disparate results, mostly related to cloud changes associated with tropical Pacific variations, similar to the changes inferred from the satellite data analysis. This suggests that this time period is not sufficient to determine longer term trends.

I'll respond to a couple of other points later.

:)P

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey

Interesting abstract, P3 - thanks for that. I'm not sure that I'm utterly convinced by the abstract, though. Perhaps it is one of those cases where you really have to read the full paper, but I was confused by this line: "In the global mean sense the surface adjusts to changes in downward solar flux instantaneously by reducing the upward fluxes of longwave, latent and sensible heat". By what process? What is it that causes the surface to spontaneously retain the extra incoming energy?

Having re-read my last post, I see that I have been a tad ambiguous at the end, so I'll write a bit more here for clarification. i said: "The obvious argument to counter this is that solar forcing is not sufficiently powerful enough to account for the observed warming trend, but CO2 forcing is. But is the magnitude of the CO2 increase actually a good fit for the temperature increase?"

I was trying to suggest (yet again - sorry to be repetitive!) that the magnitude of forcing attributed to various factors may not be accurate. I was not trying to suggest that Solar Activity is the sole (or even necessarily the major) cause of 20th Century warming - I was just trying to show that factors other than CO2 seem to be closer matches to the observed warming trend.

I was also trying to say that it strikes me as odd that the warming between 1910 and 1940 follows a gradient almost identical to that of 1970-2000 despite the significant difference in atmospheric CO2 concentrations. If CO2 is the dominant forcing then one would expect to see a steeper temperature increase over the period with higher CO2 concentrations.

That said, I look forward to your other points, P3!

:unknw:

CB

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Posted
  • Location: New York City
  • Location: New York City
I was also trying to say that it strikes me as odd that the warming between 1910 and 1940 follows a gradient almost identical to that of 1970-2000 despite the significant difference in atmospheric CO2 concentrations. If CO2 is the dominant forcing then one would expect to see a steeper temperature increase over the period with higher CO2 concentrations.

I done a little investigating into this.

I found that the gradients were different, the rate of warming 70-00 being 3.5x greater than 10-40 (CET)

Ignoring the fact that carbon dioxide is increasing exponentially, using the start and end points for the above dates I find that atmospheric carbon dioxide is 4x greater (Using the graph you posted for atmospheric carbon dioxide.)

Assuming the data to be correct, those are a reasonable match.

Don't mean to be a pain in the behind by disproving what you said, just tested your results and didn't replicate them, review stylee.

On those notes does anyone have links to atmospheric carbon dioxide annually data and world annual temprature, for use in excel?

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
I found that the gradients were different, the rate of warming 70-00 being 3.5x greater than 10-40 (CET)

Howdy, Hiya!

Just a quick question: how did you arrive at the 1970-2000 rate of warming being 3.5 times greater that the 1910-1940 warming?

The third graph I posted above has the 1970-2000 part of the line superimposed on the 1910-1940 part of the line (give or take a year or two) and the gradients appear to be, as I suggested, nearly identical. So I'm a bit confused... :unknw:

CB

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Posted
  • Location: Sunny Southsea
  • Location: Sunny Southsea

A quickie: I have read that the pre-1950s period included the solar forcings that you have documented, the post-'50s has no such forcing, instead CO2 influence is proportionally higher. I think that was it.

:)P

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
A quickie: I have read that the pre-1950s period included the solar forcings that you have documented, the post-'50s has no such forcing, instead CO2 influence is proportionally higher. I think that was it.

:)P

Sorry, just picked the kids up from school and have come back a little brain-fried! Why does the period post-1950 have no such forcing?

CB

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Posted
  • Location: Coventry,Warwickshire
  • Location: Coventry,Warwickshire

I would be very surprised if there is a linear response of warming to CO2. For a start lets talk a little about feedback and how it means different things to different people. If you talk to a computer system designer then it is about the timeliness of informtaion about the current state. In climate science it is a resulting reaction to an event which can either act to enhance the orriginal event (positive feedback) or

detract from the orrignal event( negative feedback). There will also be tipping points where these feedbacks cease to increase. Working out the actual response to CO2 increases is probably a diiferential equation of the 16th order (You need a big computer and lots of historical data to work out an aproximation).

Next we have to look a bit more closely at our historical CO2 record which largely centers around sampling air trapped within ice. As has recently been shown with inaccurate dating of ice you are not sure whether CO2 rises ahead of, or once an ice age starts. Logic would seem to suggest that CO2 should rise and then we get a climatic response but some interesting oceanic articles point out why this may not be the case. Significant cooling affects plankton which is the prime absorber of CO2 (not plants). Kill plankton off by cooling and CO2 rises (or kill plankton by preventing nutrients like iron getting to them). Aside from this scientist have to aproximate how much CO2 seeps into the ice from the trapped air, which to me means the CO2 record is open to question, not that I would deny that it should be largely correct.

Recent studies show that cloud cover does change from season to season and from year to year. This does have an impact on temperatures although the exact affect depends on heights of cloud.

NOAA Cloud fractions in the artic

Put simply changes in cloud cover can out weigh the greenhouse affect of CO2 ,whether they do is debateable. The main driving factor for cloud cover seems to be the Artic Oscillation and the Southern Oscillations. These tend to be driven by basin ocean affects, the QBO and to some extent by conditions in the very upper atmosphere.

In conclusion I think I would side with Pielke in saying I am not sure how much CO2 is warming climate, but am pretty sure they have not got all the forcings proportioned correctly, or in the case of CO2 understood all the causes of CO2 rise and their feedbacks.

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

As I understand it atmospheric CO2 is what is being queried insofar as Temp/CO2 relationships are concerned and yet I haven't read once about the planets 'sinks' for dealing with CO2 .

Surely the initial increases of CO2 are mitigated by these 'sinks' and only when the sinks are saturated do we see 'free' CO2 in our atmosphere?

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
As I understand it atmospheric CO2 is what is being queried insofar as Temp/CO2 relationships are concerned and yet I haven't read once about the planets 'sinks' for dealing with CO2 .

Surely the initial increases of CO2 are mitigated by these 'sinks' and only when the sinks are saturated do we see 'free' CO2 in our atmosphere?

It has been discussed before that the natural sinks for CO2 can't adapt quickly enough to sudden injections of CO2 into the atmosphere. The graph posted above is the atmospheric concentration of CO2, which means that it shows the amount of CO2 in the atmosphere which the natural sinks have been unable to absorb. This being the case, the sinks are irrelevant to the discussion.

;)

CB

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Posted
  • Location: Sunny Southsea
  • Location: Sunny Southsea

Here's a copy of Hegerl et.al., on the detection & attribution of anthropogenic signals in climate reconstructions of the past 1500 years: http://www.nicholas.duke.edu/people/facult...ing_inpress.pdf A fifty page document, but not a huge file.

G-W: no, the sinks don't need to be saturated for CO2 to float around, afaik.

Brick: Hegerl (above) suggest an anthro signal (CO2 + other anthro forcings) of up to 1/3 of the total warming in the first half of C20, and 'most' in the second half (?70%+?). Pielke proposes current CO2 as 25% or more, is willing to accept 30-40% as a reasonable ball-park estimate of CO2's contribution. Most 'orthodox' climate bods suggest more than 1/2, and also more likely 'most' in the second part of the 20th century (in line with Hegerl).

I think that the causes of CO2 rise are pretty well-known. The feedbacks and the proportion questions are still 'open' to interpretation. However, most if not all will agree that no other single forcing is greater than CO2. Therefore, by definition, it is the single biggest 'problem'. The only way this conclusion can be avoided is if it can be shown that the estimates of relative contributions of various forcings is at the extreme end, or beyond, the levels of the (generous) various error bars.

Yes, clouds are an issue. Lots of work being done on clouds & water vapour.

I think the CO2 record has been largely accepted: I haven't found any papers which suggest otherwise. Timings are a slightly different matter, as the recent paper showed, but the error bars are substantial. (800 +/-800 years).

C-Bob, the post 1950s have no such forcing because there has been no net increase/trend in solar activity in this period.

:)P

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......
It has been discussed before that the natural sinks for CO2 can't adapt quickly enough to sudden injections of CO2 into the atmosphere. The graph posted above is the atmospheric concentration of CO2, which means that it shows the amount of CO2 in the atmosphere which the natural sinks have been unable to absorb. This being the case, the sinks are irrelevant to the discussion.

;)

CB

Well C-Bob ,I must be the only person on the planet who does not understand the carbon cycle to the extent that I can so readily dismiss it! I was still working under the late 90's assumptions that we cannot fully appreciate ,before time, just how this complex system works.

From my own limited knowledge the Brazilian (Amazonian) CO2 experiments from the late 80's through early 90's highlights how much of a slippery a fish Carbon sinks are and just how dependant on environmental factors large areas of the system are.

Paper workings/doodlings are fine but when it comes to obsevations there can be a country mile of differences in CO2 uptakes over both Ocean and land when compared to what we 'expect' to find.

I'm happy to be further enlightened as to why we are now so certain as to the positive and negative feedbacks within the Carbon sink system as to effectively remove them from our calculations of Atmospheric CO2 levels.

Ta,

Ian.

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
C-Bob, the post 1950s have no such forcing because there has been no net increase/trend in solar activity in this period.

Ah, so you mean that they have not increased the forcing attributed to solar activity post-1950. (I thought it sounded kind of crazy to remove solar forcing completely!) We could go back to our earlier (inconclusive) debate about whether or not solar forcings can be cumulative - if they can then current warming could be caused by constant increased solar output (rather than increasing solar output).

;)

CB

EDIT - To Gray-Wolf, I think you misunderstand me. The issue we are debating is to do with atmospheric CO2's effect on climate. Regardless of how the carbon sinks work, or how efficient they are, we know for a fact that atmospheric CO2 is increasing.

I agree wholeheartedly that the climate system is more complex than we can fully appreciate - in fact, I agree to such an extent that a fair amount of my general anti-AGW argument hinges on this very fact. Aside from that I don't see that carbon sinks are anything to do with determining the potential warming effects of the measured atmospheric concentration of CO2.

I've seen it pointed out many times that (to paraphrase) "mankind is putting CO2 into the atmosphere faster than the sinks can absorb it".

CB

EDIT #2 - Sorry, GW, I think I see what the problem is - we're getting our wires crossed. I'm focusing on the recent warming that I've been harping on about today (!), but you're talking about the earlier question concerning the long-term historical debate (Vostok graph related). Am I right? In which case, yes you are quite right that carbon sinks should be taken into account - how quickly do the sinks become saturated and so on. I thought you were bringing up carbon sinks in relation to the 20th Century warming graph, as a potential explanation for the apparent similarity between 1910-1940 and 1970-2000 warming. Hence my confusion!

;)

CB

Edited by Captain_Bobski
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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......
EDIT #2 - Sorry, GW, I think I see what the problem is - we're getting our wires crossed. I'm focusing on the recent warming that I've been harping on about today (!), but you're talking about the earlier question concerning the long-term historical debate (Vostok graph related). Am I right? In which case, yes you are quite right that carbon sinks should be taken into account - how quickly do the sinks become saturated and so on. I thought you were bringing up carbon sinks in relation to the 20th Century warming graph, as a potential explanation for the apparent similarity between 1910-1940 and 1970-2000 warming. Hence my confusion!

;)

CB

It's probably as much me speed reading to catch up as your mis-understanding My point. Yes I am talking historically (as to why CO2 levels may have an initial lag behind temps) but it may also be pertinent to our near future as some carbon sinks cease to operate as effectively as they have or even become 'producers' in their own right (rain forests/temperate Forrest decline, deep water warming).

I also feel that too many folk put too much credence in our ability to understand/model climate effectively and can personally only perceive positive enhancements to current predictions without any mitigations appearing along the way.

Thanks for clearing that up, I didn't take you as being curt without a reason!

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Posted
  • Location: New York City
  • Location: New York City
Howdy, Hiya!

Just a quick question: how did you arrive at the 1970-2000 rate of warming being 3.5 times greater that the 1910-1940 warming?

The third graph I posted above has the 1970-2000 part of the line superimposed on the 1910-1940 part of the line (give or take a year or two) and the gradients appear to be, as I suggested, nearly identical. So I'm a bit confused... ;)

CB

Good old excel and the CET data from those years inclusive, linear trend, gave a gradient 3.5x greater for the more modern warming. Thats why I asked if anyone has global figures I can work with, just in case the warming is local.

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......
Good old excel and the CET data from those years inclusive, linear trend, gave a gradient 3.5x greater for the more modern warming. Thats why I asked if anyone has global figures I can work with, just in case the warming is local.

I think you might think of working on 3 graph trends!

1900-1940, 1940 -1980, 1980 to present day. I always tend to see the 1900 to 1940 as a similar rate to the 1980 to present graph with the 1940 to 1980 (representing the 'dimmed 'period) having little or no gradient. To lump the pre dimming and dimmed together will skew things (IMHO).

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Posted
  • Location: Sunny Southsea
  • Location: Sunny Southsea
Good old excel and the CET data from those years inclusive, linear trend, gave a gradient 3.5x greater for the more modern warming. Thats why I asked if anyone has global figures I can work with, just in case the warming is local.

You'll find the raw material at NOAA's NCDC site; I believe the datasets are also available. They use Smith & Reynolds & the CRU data as their standard metrics. Failing NCDC you could try Hadley or the CRU, or the Tyndall; the information should be ready to hand.

:)P

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
Good old excel and the CET data from those years inclusive, linear trend, gave a gradient 3.5x greater for the more modern warming. Thats why I asked if anyone has global figures I can work with, just in case the warming is local.

The graph I referenced was taken from Wikipedia, though the graph itself originates from the Hadley Centre (or, as Wiki put it: "This image shows the instrumental record of global average temperatures as compiled by the Climatic Research Unit of the University of East Anglia and the Hadley Centre of the UK Meteorological Office.") The graph is of global temperatures.

The graph's 1910-1940 and 1970-2000 gradients certainly seem near identical, though it is eminently possible that the average temperature in the UK follows different trends since we do seem ideally placed to get the extremes of everything! Presumably if the average temp change in the UK is above the global average then there is a part of the world that is sufficiently below the average to balance it out.

Do you agree that, at least as far as the global temperature graph goes, the warming now is on a par with the warming post-1910? If so then does it not strike you as rather odd that global temperatures have only risen at the same rate now as compared with 1910-1940, considering that CO2 levels have increased by four times as much as then?

;)

CB

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Posted
  • Location: New York City
  • Location: New York City
I think you might think of working on 3 graph trends!

1900-1940, 1940 -1980, 1980 to present day. I always tend to see the 1900 to 1940 as a similar rate to the 1980 to present graph with the 1940 to 1980 (representing the 'dimmed 'period) having little or no gradient. To lump the pre dimming and dimmed together will skew things (IMHO).

I haven't a clue what your on about, but I'm denying it.

The graph I referenced was taken from Wikipedia, though the graph itself originates from the Hadley Centre (or, as Wiki put it: "This image shows the instrumental record of global average temperatures as compiled by the Climatic Research Unit of the University of East Anglia and the Hadley Centre of the UK Meteorological Office.") The graph is of global temperatures.

The graph's 1910-1940 and 1970-2000 gradients certainly seem near identical, though it is eminently possible that the average temperature in the UK follows different trends since we do seem ideally placed to get the extremes of everything! Presumably if the average temp change in the UK is above the global average then there is a part of the world that is sufficiently below the average to balance it out.

Do you agree that, at least as far as the global temperature graph goes, the warming now is on a par with the warming post-1910? If so then does it not strike you as rather odd that global temperatures have only risen at the same rate now as compared with 1910-1940, considering that CO2 levels have increased by four times as much as then?

:)

CB

I can't say either way until I get hold of the data set, which I can't find due to my uselessness at life.

pppsssssst remember I'm of the same viewpoint as you

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......
Do you agree that, at least as far as the global temperature graph goes, the warming now is on a par with the warming post-1910? If so then does it not strike you as rather odd that global temperatures have only risen at the same rate now as compared with 1910-1940, considering that CO2 levels have increased by four times as much as then?

:)

CB

Personally, stuck in my world of black and white 'understanding' ,I find it a bit troubling.

Excuse both my Lack of technical understanding and my 'Lovelockian' take on things but it is the only way I could hope to explain or understand any of this!

So , lets say we pop back to 1840 and have a look at the Northern Hemisphere. First signs of industrialisation, first 'industrial scale' greenhouse pollution.

So it all begins quite slowly. Low chimney stacks, poor fuel efficiency, CO2 and soot, lots of soot (oh yes and a whole host of the other gasses). Come the 1900's and the push towards conflict drives massive expansion in iron workings/chemical processing/Urbanisation so the dirty fuels (still pumping out dirty pollution) step up another gear.

War. Both industrial pollution and some 'war pollution'. Spurt of automotive evolution spurred on by weight power ratio's for aero engines (for bombing purposes). Widescale introduction of electricity to replace gas as home lighting. Better fuel efficiencies. More industry, more pollution.

Enough 'changes' have now have now accrued to allow global temps to respond (at first the levels of 'pollutants' were absorbed by the planets onboard 'pollution control' but now more and more are left to affect the atmospheric 'mix').

By the start of the 1940's we were capable of creating 'con trials' from aircraft. Fuel economy grows.Use of electricity grows, industrial/chemical processing grows. Chimney height grows, soot particle diameters decrease,Pollution grows.CO2 levels continue to rise.

The increased use of Petrochemicals, released at all levels of the troposphere, increasingly effect both the strength of the sun at the earths surface and the rates of pan evaporation across the globe. Global temps 'stablise'. CO2 levels continue to rise.

1980 onwards. Clean air acts start to show effect across the industrialised countries. Global temps rise at around the rate of 1910-1940 warming.CO2 levels continue to rise.

As I have outlined the planet could absorb, through it's various 'systems', the first increases in CO2 without very much 'extra' being added to the already existing CO2 levels.

Once the CO2 production was putting out more 'significant' amounts of CO2 (whist the added amounts continue to accrue) some larger percentage of 'free' CO2 was being added to the global levels. CO2 levels continue to rise.

Against this particulate pollution both decreased in physical size and was 'lofted ' higher by ever more efficient 'stacks' taking the smaller and smaller particulates and the gasses higher and higher into the air column. And more and more and more of it.

To complete the chemical 'seeding' of the troposphere we introduce aircraft in ever increasing numbers to ever increasing heights. And we do this year in year out for forty years (we can see from the Mt. St. Helen's eruption just how far a few weeks of high level polluting can travel when lofted high enough).

We realise the impact to the planet in terms of health and pollution in the industrialised world so as to make 'cleaner air' a policy. Gradual stabilisation and reduction of target pollutants. Ozone hole drives 'aerosol' awareness so more gas reductions.

Pan evaporation rates, strength of sunlight at surface increase. Global temps increase at greater speed. More CO2 added to highest global levels in millions of years.

To get that reduction in pan evap. rates/global sun strength over a 40yr period and yet to keep temps stable in a CO2 enriching atmosphere seem to point to a 'masking' of temperature rise rates and not a fall in global temps (as the 'cumulative' effects of both an increase of pollution levels and an increase of the ice/snow cover albino as temps fall responding to lower solar inputs leads to growths in ice/snow fields) that I'd expect.

So if something was effectively starving the Earth of the Suns strength what the Frell was negating that 'cooling' to produce the near 'flat line' over that period???

I rather think we are seeing ,in the 'Dimming Period' the end of one period/type of polluting and it's replacement with another (the second being the 'proposed' reason for the dimming). The changes in fuel efficiency/fuels of choice over the end 19th/start 20th centuries must have had an impact on the seeding of the atmosphere (northern hemisphere) with ever increasing numbers of hygroscopic particles and ever increasing amounts of gasses (as opposed to part burnt/part spent fuels from the earlier period). I mean look at the energy you can reap from a tonne of coal today compared with in the 1750's! and then consider the types of pollutants you'd get from either 'burn'.

If the 'Dimming' is the combination of 2 periods of pollution (one ending but masking the birth of the other) for us to then deal with the second 'pulse' (which would have similar constituents to the first pulse) in the clean air legislation/movements of the 60's and 70's then it'd take a lot longer for the reductions to take hold than the 10yrs that the graph shows us. The planet is a big mass.

So what if the 'rises' that kept the planet 'stable' over this 40yr period were responsible for the recent (1980-2005)temperature rises and not the return to normal pan evap rates/sunlight strength which took a while to manifest and are only starting to impact right about now. Don't forget throughout this period CO" levels have been rising.

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey

To Hiya, I'm fairly sure you can get the data in tabular form from the NOAA website - if I can find it before you do then I'll post a link. The graph, though, uses the same data (or roughly the same data, anyway, but Hadley Centre's data rather than NOAA's, which may or may not be identical), but presents it in a visual format. This format makes it a simple matter of comparing the angle of the 1910-1940 line with the angle of the 1970-2000 line - or am I oversimplifying? (I know you're on the same side as me - I just want to make sure we're reading from the same page! :) )

To GW, I can agree (at least in principle) with what you've written there - all things being equal it seems like a pretty good scenario. I guess my misgivings come largely from the fact that, if CO2 really is the dominant forcing, it would require a confluence of coincidences (I do like a nice piece of alliteration!) for the 1970-2000 warming to be near identical to the 1910-1940 warming. Considering the vast differences in the climatological makeup, it seems uncanny that there should be such striking similarities.

The "Pro-AGW" group points out how unlikely it is that the increase in temperature should so nicely coincide with the Industrial Revolution (and hence with CO2 increases) without there being a cause and effect relationship between them. That's a "First Order" coincidence - one thing (temp rise) happens coincidentally with another (the Industrial Revolution). But for the recent warming to be so similar to the early 20th Century warming despite the apparently "important" differences would require so many coincidences (aerosols, particulates, CO2, solar activity perhaps, and so on) that it beggars belief (my personal belief, at any rate!).

That's my current thinking... :)

CB

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  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......

But most of climate is a 'confluence of coincidences' with various 'oscillations' competing with one another to bring about larger ENSO type events so why not here. We just need trace the evolution of our pollution and the increases in it's volume over time to map how its influence on the planet changes over time as we become ever more sophisticated and globally widespread in our processing.

Sychronistically enough the Horizon prog. on global dimming was repeated at the end of last night and reminded me, via 9/11, of the 1c increase in temp range across the US whilst their planes were grounded implying that the con trails alone were masking a 1c temp rise and never mind the rest of the particulate pollution!

It does make me think that we have greatly underestimated the strength of forcing that CO2 produces because we are too busy massaging the figures to fit the observations just to convince the 'naysayers' of the CO2 problem.

As we in the developed world 'clean up our act' so temps start to accelerate over our countries. We should expect solar strength falls across the Pacific basin as the indo-chinese impact takes hold there and all along more CO2 and more accrued warmth. What then when we help the developing world to clean up it's act? certainly not 1-3c over 100yrs I'll wager!

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  • Location: New York City
  • Location: New York City
To Hiya, I'm fairly sure you can get the data in tabular form from the NOAA website - if I can find it before you do then I'll post a link. The graph, though, uses the same data (or roughly the same data, anyway, but Hadley Centre's data rather than NOAA's, which may or may not be identical), but presents it in a visual format. This format makes it a simple matter of comparing the angle of the 1910-1940 line with the angle of the 1970-2000 line - or am I oversimplifying? (I know you're on the same side as me - I just want to make sure we're reading from the same page! :) )

No your not oversimplifying, I just like to start with the raw data and build up, I've developed a distrust for pre-made graphs.

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  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey

Hiya - I've followed some links from the Hadley Centre and found this:

http://www.cru.uea.ac.uk/cru/data/temperature/

About half way down the page is a section headed "Data for Downloading". Selecting any of the five "GL" links in the "Hemispheric Means" column will open up a text file with raw global temperature data in (in deviation from mean values). Hope this is what you're looking for. :)

GW - While I agree that any confluence of events could be described as being coincidental (in that they are two or more events which coincide), I find it unusual that so many events should happen to coincide in such a way as to cause the 1970-2000 warming trend gradient to not deviate from the 1910-1940 warming trend gradient in any substantial way. It is possible that such a setup could occur, but considering the vast differences in human inputs over the two periods it would seem unlikely that these changes should balance each other out in such a way that the overall net effect is identical. Unless, of course, the human inputs - especially CO2 - were of lesser importance than has been assumed.

:)

CB

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