THIS PAGE HAS BEEN ACTIVATED AS THE NEW STATESMAN BLOG IS NOW CLOSED FOR COMMENTS
At 10am this morning, the New Statesman finally closed the Mark Lynas thread on their website after 1715 comments had been added over a period of five months. I don’t know whether this constitutes any kind of a record, but gratitude is certainly due to the editor of of the New Statesman for hosting the discussion so patiently and also for publishing articles from Dr David Whitehouse and Mark Lynas that have created so much interest.
This page is now live, and anyone who would like to continue the discussion here is welcome to do so. I have copied the most recent contributions at the New Statesman as the first comment for the sake of convenience. If you want to refer back to either of the original threads, then you can find them here:
Dr David Whitehouse’s article can be found here with all 1289 comments.
Mark Lynas’ attempted refutation can be found here with 1715 comments.
Welcome to Harmless Sky, and happy blogging.
(Click the ‘comments’ link below if the input box does not appear)
10,000 Responses to “Continuation of the New Statesman Whitehouse/Lynas blogs.”
Sorry, the comment form is closed at this time.
Hi David,
“The decadal cooling from the 1940s to the 1950s is due to a combination of aerosols plus solar forcings, I believe. In any case, it has not been repeated (so far), which is certainly to the point.”
The cooling actually lasted a bit longer, from around 1944 to 1976, according to the Hadley record. And we’ll have to wait a few more years to see whether or not it is being repeated today.
But what does IPCC say about the mid-century global cooling?
There is very little mention of this global cooling period in the latest IPCC AR4 WG1 report. Two references are cited, both in the “Frequently Asked Questions” Section 9.2 (pp.104,120): “From about 1940 to 1970 the increasing industrialization following World War II increased pollution in the Northern Hemisphere, contributing to cooling, and increases in carbon dioxide and other greenhouse gases dominate the observed warming after the mid-1970s.” “During the 1950s and 1960s, average global temperatures leveled off, as increases in aerosols from fossil fuels and other sources cooled the planet.” No hard data are presented to support these suggestions.
http://www.ipcc.ch/pdf/assessment-repor … 1-faqs.pdf
What makes this cooling trend even more of an anomaly is that during this period of post WWII boom the emissions of man-made CO2 were growing exponentially, while economic growth was booming, fossil fuel energy costs were extremely low and few worried about energy conservation. Atmospheric CO2 concentration rose by 25 ppmv over this period, as compared to only 15 ppmv during the immediately preceding period (i.e. the period of highest warming observed in the 20th century, from 1910 to 1944).
The IPCC message here is that the warming effect of globally increasing CO2 levels was temporarily overwhelmed by an increase in human particulates and aerosol pollution.
This phenomenon has been given the name of “global dimming”, although IPCC states in its report: “’Global dimming’ is neither global in extent nor has it continued after 1990.”
While IPCC makes very little direct reference to it, this suggested explanation is very “convenient” as it attempts to explain what would otherwise be a fairly strong argument against CO2 as the principle driver of climate, i.e. strong temperature increase from 1910 to 1944 (when there was little increase in CO2 and subsequent temperature decrease from around 1944 to 1976 (when there was a much larger increase in CO2).
There are, however, some problems with the explanation of “global dimming due to anthropogenic aerosols”:
First and foremost, the suggested aerosol explanation for the mid-century temperature drop is based on theory alone. There is no observational physical evidence for strong anthropogenic aerosol cooling on a global basis during this period. The data are just not there.
The regions that produce aerosols have shown warming in recent years, and those that cooled from 1944-1976 were not necessarily those regions where aerosols were supposed to have any discernable effect. In other words, the actual observations do not support this cause-effect relationship for the mid-century cooling as suggested by the IPCC.
Those areas that were not affected by aerosols show the 1944-1976 cooling trend. This is evident in IPCC Southern Hemisphere temperature records for the last century. The question must be answered: how did “increased pollution in the Northern Hemisphere”, as postulated by IPCC, affect temperatures in the Southern Hemisphere?
Next, regions that produce massive amounts of aerosols today do not show cooling at all. They actually show warming.
During the period from the 1950s to around 1980, there was negligible increase in temperatures in China. There was also negligible economic growth. Starting in the 1990s, there has been explosive economic growth in China with tremendous increases not only in CO2 but also in aerosol and sulfate emissions. If the mid-century “global dimming” hypothesis were valid, these emissions should presumably cause local cooling today as they are supposed to have done from 1944 to 1976, yet there has been a sharp increase in temperatures in China.
If we look at global emissions of the principle aerosol, sulfur dioxide, we see that these have increased steadily from around 28 to 72 million metric tons per year over the period 1945 to 1980 (expressed as sulfur), then decreased slightly to around 65 million metric tons per year in 1995 before increasing again to around 77 million metric tons per year today, where they now stand at a record high. The latest increase has occurred primarily in Asia, while both North America and Europe have seen significant decreases since around 1980. On a global basis, however, SO2 emissions have not been reduced, but have remained roughly constant or even increased slightly. In other words, there is no reason that aerosol emissions should have caused a cooling effect from 1944 to 1976 and then not continued to cause cooling after 1980 on a global basis.
Since the residence time of sulfur dioxide and sulfates in the atmosphere is very short (from 2 to 6 days), there is not much of a cumulative impact, and today’s record rates of SO2 emissions (77 Mtons/year) should show a higher cooling effect than the much lower rates, which occurred in the 1950s and 1960s (30 to 45 Mtons/year) and which are blamed for the cooling trend then.
Another argument points away from the suggestion that the mid-century cooling was caused by anthropogenic aerosols. Since the beginning of the industrial revolution sulfates and CO2 emissions have largely increased together, and on a proportional basis sulfate emissions were higher than greenhouse gases during the early industrial revolution when there were no automobiles or diesel engines and a higher percentage of the CO2 emissions came from (relatively high sulfur content) coal rather than oil, diesel fuel or gasoline. This period was also before there were any environmental regulations governing sulfur pollution. Since the temperature record shows that the industrial revolution, as indeed the period from 1910 to 1944, was not accompanied by cooling, the suggestion that cooling in the mid 20th century was caused by sulfates can be seriously questioned.
And finally, Europe and the USA have seen a recent massive cleanup of sulfate aerosols, and indeed the temperature rose in these regions over the same period. The suggestion is that pollution regulations and improved technology saw a decrease in aerosol emissions and as the air cleared, the CO2 signal again emerged and took over.
If one were to accept the explanation for mid-century cooling as having been caused by anthropogenic aerosol emissions, then the aerosol reduction in the USA and Western Europe would have had a sufficiently high impact that CO2 would not even have been needed to explain the subsequent warming in these regions. As Hans Erren points out graphically, if all of the cooling in the USA from 1950 to 1975 were caused by increasing aerosols (Schneider et al) then all of the warming since 1975 could well be caused simply by eliminating a major portion of these aerosols.
http://home.casema.nl/errenwijlens/co2/usso2vst.gif
In other words, the IPCC’s suggested anthropogenic aerosol explanation for the global cooling experienced from 1944 to 1976 makes a good story that superficially “fits” the AGW theory but, upon closer examination, it has several serious flaws and inconsistencies and can therefore be dismissed.
Regards,
Max
Looks like the link to IPCC FAQ got garbled.
http://www.ipcc.ch/pdf/assessment-repor … 1-faqs.pdf
Here goes again.
http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-faqs.pdf
Is it the sun?
http://www.globalwarmingart.com/wiki/Image:Solar_Variation_to_Temperature_Comparison_png
At least not since 1950 CE.
And as for aerosols, poster manacker just continues to MSU without any quantitative support. At least he ought to read the IPCC AR4 WG1 Technical Summary…
David (a diversion from your debate with Max) – re Joe’s blog:
To a post claiming that the IPCC’s 2007 report called “for immediate action to save humanity from the deadly consequences of unrestrained greenhouse gas emissions”, having failed to get him to provide the reference to the IPCC’s alleged comment, I noted (accurately – I checked) that nowhere in the report does the IPCC make such a call, adding that his claim “is a misrepresentation of its carefully chosen and measured phrasing”.
Joe replied, “I always find it strange when people who don’t accept what the IPCC says tell me what it says.”
To this, I tried to reply, “I did not tell you what the IPCC is saying, rather what it is not saying … it does not, as you claim, ‘call for immediate action to save humanity from the deadly consequences of unrestrained greenhouse gas emissions’. You do your readers a disservice by misleading them on this.”
Joe, however, refused to publish that. Yet it was consistent with his site’s Terms and Conditions – I checked them – and wasn’t remotely a “modern version of flat-earthism”. I think he just didn’t like my comment and decided to censor it.
Surely you agree that such action is hardly conducive to intelligent debate?
Max wrote on June 22nd, 2008 AD at 9:44 pm an excellent analysis with many demonstrations that the IPCC exclusivity ASSUMED for aerosols in the mid century cooling period, cannot be supported.
David B. Benson responded at 9:56 pm that is 12 minutes later, in part:
“And as for aerosols, poster manacker just continues to MSU without any quantitative support.”
My word David, you are so quick, to be able to digest so much information in minutes, and instantly determine that it was made-up. Could you perhaps pick-out just one point and show that it IS made-up.
You also found time in just minutes to try and change the subject, and accuse Max of not reading the Technical Summary…..How do you know that? I would be very surprised if he did not!
WHY do you want to CHANGE the subject?
Re my 62 and David Benson’s 69
I was stunned to see David write in part:
“I know of no 20 year smoothed product from the Hadley Centre site (although I haven’t searched hard for it.)”
If you look again at the graph I posted in 62, you will see that the blue smoothed line is described as using the standard Hadley 21-point smoothing. This means that a “bell curve” average, 10 years each side of the moving average centre-point is applied. Of course, to get such an average for 2007, data is needed out to 2017, which is tricky, so they MSU, but are good enough to show it as a broken line in the last ten years
You continued:
“I find the decadal averages to be much easier to read than the raw product.”
Tamino does a good job doesn’t he? However, what is difficult to read in the Hadley 20-year smoothed average? You still have not explained why you think that Tamino stuff is better than Hadley.
You continued:
“The decadal cooling from the 1940s to the 1950s is due to a combination of aerosols plus solar forcings, I believe. In any case, it has not been repeated (so far), which is certainly to the point.”
Are you saying that the current plateau has no similarity to that in 1940? You have not responded to some of the points I raised in 62
Here you are………
May 22, 2008
Almost No Correlation Between Climate Models And Reality
http://ginacobb.typepad.com/gina_cobb/2008/05/near-zero-corre.html
This new study goes on to examine six popular Climate Models, by looking at old temperature data from different locations on the planet. Then they try predict the weather and climate using the models. All the models failed completely. They were no better than chance, and the correlation between their predictions and the real weather were almost zero.
Hi David,
You skipped about a bit with: “Is it the sun?
At least not since 1950 CE.
And as for aerosols, poster manacker just continues to MSU without any quantitative support. At least he ought to read the IPCC AR4 WG1 Technical Summary…”
David, you truly have a knack for waffling, but at least being consistent in getting it wrong every time. Your “MSU” BS is just that. Check the facts, man, and you’ll see that the IPCC’s aerosol rationalization for the mid-century cooling is a classical example of “MSU”. Yeah I read the IPCC AR4 WG1 Technical Summary (groan!). No factual evidence to support the “aerosol” suggestion.
Now to your question “Is it the sun?” Duh! What drives our climate on this planet? Black Wallaby’s SUV or the sun? Get serious, David. I believe you are an engineer, so you should be able to figure out some basic facts.
But since you brought it up, let’s talk about the sun as a driver of Earth’s climate. And (since you prefer longer term trends) let’s not just limit it to “since 1950 CE”.
The Hadley global average land and sea surface temperature anomaly recorded a linear increase of 0.65C over the 20th century (1901-2000). IPCC TAR reported this as 0.6C and then later revised it to 0.74C in 2007 SPM by replacing five years of cooling at the beginning of the record (1901-1905) with five essentially “flat” years at the end of the record (2001-2005).
IPCC states that CO2 increased from around 280 ppmv (pre-industrial level in year 1750) to 379 ppmv in 2005 (p.2), resulting in a radiative forcing of 1.66 W/m² (p.4).
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf
The second most important greenhouse gas, methane, increased from 715 ppbv to 1774 ppbv over the same time period (p.2), resulting in a radiative forcing of 0.48 W/m² (p.4).
According to IPCC, warming from other less important GHGs is essentially cancelled out by cooling from land use changes and aerosols.
If we adjust the radiative forcing to cover the period 1901 to 2000, we have CO2 increasing from around 290 ppmv in 1901 to 370 ppmv in 2000 and CH4 from around 800 ppbv to 1774 ppbv over the same period, resulting in a RF for CO2 of 1.3 W/m² and for CH4 of 0.42 W/m².
Applying Stefan-Boltzmann, this gives us a theoretical greenhouse warming of 0.24C for CO2 and 0.08C for CH4 over the 100 years.
IPCC states that the RF from changes in solar irradiance since 1750 is only around 0.12 W/m², but concedes that the “level of scientific understanding” of this factor is “low”.
There have been many studies, which show that the solar impact is actually much higher.
Solanki et al (2004) conclude that “the level of solar activity during the past 70 years is exceptional, and the previous period of equally high activity occurred more than 8,000 years ago.” They do state, however, that solar activity alone cannot explain the most recent warming.
http://cc.oulu.fi/~usoskin/personal/nature02995.pdf
http://www.ncdc.noaa.gov/paleo/pubs/solanki2004/solanki2004.html
Ponyavin et al (2005) state that “It is shown that solar cycle signal is more evident in climatic data during the last 60 years. The result is discussed in conjunction with the problem of unprecedented high level of sunspot activity and climate warmth in the late 20th century.”
http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76.1026I.pdf
Usoskin et al (2006) conclude that “We have revised the earlier sunspot activity reconstruction since 5000 BC, using the new geomagnetic data series, and found that it is roughly consistent with the previous results during most of the period, although the revised sunspot number values are in general higher. Nonetheless, it is confirmed with the new palaeomagnetic series that the Sun spends only 2–3% of the time in a state of high activity, similar to the modern episode. This strengthens the conclusion that the modern high activity level is very unusual during the last 7000 years.”
http://www.agu.org/pubs/crossref/2006/2006GL025921.shtml
Geerts and Linacre (1997) constructed a profile of atmospheric climate “forcing” due to combined changes in solar irradiance and emissions of greenhouse gases between 1880 and 1993. They found that the temperature variations predicted by their model accounted for up to 92% of the temperature changes actually observed over the period – an excellent match for that period. Their results also suggest that the sensitivity of climate to the effects of solar irradiance is about 27% higher than its sensitivity to forcing by greenhouse gases.
http://www-das.uwyo.edu/~geerts/cwx/notes/chap02/sunspots.html
Using up-dated satellite data, Willson (2003) concluded that “the accurate long-term dataset therefore shows a significant positive trend (.05 percent per decade) in TSI between the solar minima of solar cycles 21 to 23 (1978 to present)” and “historical records of solar activity indicate that solar radiation has been increasing since the late 19th century. If a trend comparable the one found in this study persisted during the 20th century it would have provided a significant component of the global warming that the Intergovernmental Panel on Climate Change report claims to have occurred over the last 100 years.” Willson indicates that if the current rate of increase of solar irradiance continues until the mid 21st century, then the surface temperatures will increase by about 0.5ºC. This is small, but not a negligible fraction of the expected greenhouse warming.
http://www.earthinstitute.columbia.edu/news/2003/story03-20-03.html
Soon et al (1996) pointed out that “a change of, say, 0.4 percent in the total solar irradiance over a time frame of 100 years is about 1 Watt/m2 at the surface of the earth. Since the known increase in greenhouse gas radiative forcing is over 2 Watts/m2 in the last 100 years, it is supposed that the sun has been and will continue to be of lesser importance compared to the forcing from the increase in greenhouse gases. However, such a comparison misses a key point: it is not the arithmetic magnitude of the forcings per se but the responses of the climatic system to these forcings that must be considered. The conjecture that the two radiative inputs give similar responses in the climatic system is an unverified assumption.”
“Computer simulations of the climate suggest that roughly 0.4 percent changes in solar irradiance over many decades would produce global temperature change of about 0.5ºC (Soon, Posmentier and Baliunas 1996: 891). There is evidence of a solar change of just this magnitude in a recent report of an observed difference of total solar irradiance between two sunspot-cycle minima-1986 and 1996-that would amount to about 0.4 percent change in irradiance over a century (Willson 1997:1963).”
The authors also point out that change in total solar irradiance is not the sole driver of solar-influenced climatic change. “The signature of solar variability appears in meteorological records in ways that suggest that change in total irradiance is not the only impact the sun has on the terrestrial climate”. “The consequence of the existence of these significant non-radiative mechanisms of solar influence on climatic change is important: the assumption of equivalence in the radiative inputs of the sun and increases in greenhouse gases is not valid.”
http://oldfraser.lexi.net/publications/books/g_warming/solar.html
Dietze (1999) referred to a study by Lockwood and Stamper (1996) which showed a good correlation between magnetic field and solar brightness for the interval 1901-1995, indicating a rise in the average total solar irradiance of about 1.65 W/m² or 0.12%, and a solar increment to warming over the period of 0.35K, concluding that “solar brightening could explain roughly half of global warming during the last 100 years.”
http://www.john-daly.com/fraction/fraction.htm
http://www.wdc.rl.ac.uk/wdcc1/papers/grlcover.html.
In an earlier study, Gérard and Hauglustaine (1991) stated that “a temperature response range of 1.1 to 2.3°C for a 1% solar irradiance increase is predicted by climate models.” “It is thus concluded that, if the climatic evolution is controlled in part by solar activity, other factors than the photospheric and chromospheric indeces must be used to describe the evolution of the solar output and its secular evolution. For example, a changing magnetic field in the solar convection zone would possibly be able to produce luminosity changes reaching 1%.”
http://www.int-res.com/articles/cr/1/c001p161.pdf
Georgieva et al (2005) showed that using the sunspot number alone as an indicator of solar forcing resulted in good correlation with temperature until around 1980. “Solar activity, together with human activity, is considered a possible factor for the global warming observed in the last century. However, in the last decades solar activity has remained more or less constant while surface air temperature has continued to increase, which is interpreted as evidence that in this period human activity is the main factor for global warming. We show that the index commonly used for quantifying long-term changes in solar activity, the sunspot number, accounts for only one part of solar activity and using this index leads to an underestimation of the role of solar activity in the global warming in the recent decades. A more suitable index is geomagnetic activity which reflects all solar activity, and is highly correlated to global temperature variations in the whole period for which we have data.” “The geomagnetic activity reflects the impact of solar activity originating from both the closed and open magnetic field regions, so it is a better indicator of solar activity than the sunspot number which is related to only closed magnetic field regions.”
The authors propose that there are three “mechanisms for solar influence on climate:
1. variations in the total solar irradiance leading to variations in the direct energy input into the Earth’s atmosphere (Cubasch and Voss 2000):
2. variations in solar UV irradiance causing variations in stratospheric chemistry and dynamics (Hood 2003):
3. variations in solar wind modulating cosmic ray flux which affects the stratospheric ozone and small constituents (Veretenenko and Pudovkin 1999) and/or the cloud coverage (Svensmark and Friis-Christensen 1997), and thus the transparency of the atmosphere.”
The authors conclude: “So the sunspot number is not a good indicator of solar activity, and using the sunspot number leads to the under-estimation of the role of solar activity in the global warming.”
http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf
So there is a lot of information out there that confirms a significant warming impact from solar variation (maybe not enough to account for all the observed warming, but much higher than that assumed by IPCC with its admitted “low level of scientific understanding”). These studies also “shoot down” the Wikipedia graph you posted.
The estimated solar impact on 20th century warming in the various studies varies from less than 0.1C to a major part of the total observed warming. If we take the average estimate from all the studies, we arrive at a rise in the average total solar irradiance of about 1.65 W/m² over the 20th century, which yields a solar increment to 20th century warming of 0.35C. This would seem to be a reasonable estimate.
So we have in summary for the period 1901-2000:
0.24C warming from CO2, 0.08C warming from CH4 and 0.35C warming from solar, for a total of 0.67C (compared to an observed warming of 0.65C). Not bad.
This would indicate that around half of the observed 20th century warming came from GHGs (primarily anthropogenic) and the other half from natural solar variability.
It would also raise some serious questions regarding the validity of the assumed positive feedbacks being cranked into the GCMs, since the total observed warming can be explained without complicating matters by adding in these theoretical but totally unproven net positive feedbacks.
Max
Sending this again without all the links, since the “spam filter” seems to have problems with lots of links (links will follow separately)
Hi David,
You skipped about a bit with: “Is it the sun?
At least not since 1950 CE.
And as for aerosols, poster manacker just continues to MSU without any quantitative support. At least he ought to read the IPCC AR4 WG1 Technical Summary…”
David, you truly have a knack for waffling, but at least being consistent in getting it wrong every time. Your “MSU” BS is just that. Check the facts, man, and you’ll see that the IPCC’s aerosol rationalization for the mid-century cooling is a classical example of “MSU”. Yeah I read the IPCC AR4 WG1 Technical Summary (groan!). No factual evidence to support the “aerosol” suggestion.
Now to your question “Is it the sun?” Duh! What drives our climate on this planet? Black Wallaby’s SUV or the sun? Get serious, David. I believe you are an engineer, so you should be able to figure out some basic facts.
But since you brought it up, let’s talk about the sun as a driver of Earth’s climate. And (since you prefer longer term trends) let’s not just limit it to “since 1950 CE”.
The Hadley global average land and sea surface temperature anomaly recorded a linear increase of 0.65C over the 20th century (1901-2000). IPCC TAR reported this as 0.6C and then later revised it to 0.74C in 2007 SPM by replacing five years of cooling at the beginning of the record (1901-1905) with five essentially “flat” years at the end of the record (2001-2005).
IPCC states that CO2 increased from around 280 ppmv (pre-industrial level in year 1750) to 379 ppmv in 2005 (p.2), resulting in a radiative forcing of 1.66 W/m² (p.4).
The second most important greenhouse gas, methane, increased from 715 ppbv to 1774 ppbv over the same time period (p.2), resulting in a radiative forcing of 0.48 W/m² (p.4).
According to IPCC, warming from other less important GHGs is essentially cancelled out by cooling from land use changes and aerosols.
If we adjust the radiative forcing to cover the period 1901 to 2000, we have CO2 increasing from around 290 ppmv in 1901 to 370 ppmv in 2000 and CH4 from around 800 ppbv to 1774 ppbv over the same period, resulting in a RF for CO2 of 1.3 W/m² and for CH4 of 0.42 W/m².
Applying Stefan-Boltzmann, this gives us a theoretical greenhouse warming of 0.24C for CO2 and 0.08C for CH4 over the 100 years.
IPCC states that the RF from changes in solar irradiance since 1750 is only around 0.12 W/m², but concedes that the “level of scientific understanding” of this factor is “low”.
There have been many studies, which show that the solar impact is actually much higher.
Solanki et al (2004) conclude that “the level of solar activity during the past 70 years is exceptional, and the previous period of equally high activity occurred more than 8,000 years ago.” They do state, however, that solar activity alone cannot explain the most recent warming.
Ponyavin et al (2005) state that “It is shown that solar cycle signal is more evident in climatic data during the last 60 years. The result is discussed in conjunction with the problem of unprecedented high level of sunspot activity and climate warmth in the late 20th century.”
Usoskin et al (2006) conclude that “We have revised the earlier sunspot activity reconstruction since 5000 BC, using the new geomagnetic data series, and found that it is roughly consistent with the previous results during most of the period, although the revised sunspot number values are in general higher. Nonetheless, it is confirmed with the new palaeomagnetic series that the Sun spends only 2–3% of the time in a state of high activity, similar to the modern episode. This strengthens the conclusion that the modern high activity level is very unusual during the last 7000 years.”
Geerts and Linacre (1997) constructed a profile of atmospheric climate “forcing” due to combined changes in solar irradiance and emissions of greenhouse gases between 1880 and 1993. They found that the temperature variations predicted by their model accounted for up to 92% of the temperature changes actually observed over the period – an excellent match for that period. Their results also suggest that the sensitivity of climate to the effects of solar irradiance is about 27% higher than its sensitivity to forcing by greenhouse gases.
Using up-dated satellite data, Willson (2003) concluded that “the accurate long-term dataset therefore shows a significant positive trend (.05 percent per decade) in TSI between the solar minima of solar cycles 21 to 23 (1978 to present)” and “historical records of solar activity indicate that solar radiation has been increasing since the late 19th century. If a trend comparable the one found in this study persisted during the 20th century it would have provided a significant component of the global warming that the Intergovernmental Panel on Climate Change report claims to have occurred over the last 100 years.” Willson indicates that if the current rate of increase of solar irradiance continues until the mid 21st century, then the surface temperatures will increase by about 0.5ºC. This is small, but not a negligible fraction of the expected greenhouse warming.
Soon et al (1996) pointed out that “a change of, say, 0.4 percent in the total solar irradiance over a time frame of 100 years is about 1 Watt/m2 at the surface of the earth. Since the known increase in greenhouse gas radiative forcing is over 2 Watts/m2 in the last 100 years, it is supposed that the sun has been and will continue to be of lesser importance compared to the forcing from the increase in greenhouse gases. However, such a comparison misses a key point: it is not the arithmetic magnitude of the forcings per se but the responses of the climatic system to these forcings that must be considered. The conjecture that the two radiative inputs give similar responses in the climatic system is an unverified assumption.”
“Computer simulations of the climate suggest that roughly 0.4 percent changes in solar irradiance over many decades would produce global temperature change of about 0.5ºC (Soon, Posmentier and Baliunas 1996: 891). There is evidence of a solar change of just this magnitude in a recent report of an observed difference of total solar irradiance between two sunspot-cycle minima-1986 and 1996-that would amount to about 0.4 percent change in irradiance over a century (Willson 1997:1963).”
The authors also point out that change in total solar irradiance is not the sole driver of solar-influenced climatic change. “The signature of solar variability appears in meteorological records in ways that suggest that change in total irradiance is not the only impact the sun has on the terrestrial climate”. “The consequence of the existence of these significant non-radiative mechanisms of solar influence on climatic change is important: the assumption of equivalence in the radiative inputs of the sun and increases in greenhouse gases is not valid.”
Dietze (1999) referred to a study by Lockwood and Stamper (1996) which showed a good correlation between magnetic field and solar brightness for the interval 1901-1995, indicating a rise in the average total solar irradiance of about 1.65 W/m² or 0.12%, and a solar increment to warming over the period of 0.35K, concluding that “solar brightening could explain roughly half of global warming during the last 100 years.”
In an earlier study, Gérard and Hauglustaine (1991) stated that “a temperature response range of 1.1 to 2.3°C for a 1% solar irradiance increase is predicted by climate models.” “It is thus concluded that, if the climatic evolution is controlled in part by solar activity, other factors than the photospheric and chromospheric indeces must be used to describe the evolution of the solar output and its secular evolution. For example, a changing magnetic field in the solar convection zone would possibly be able to produce luminosity changes reaching 1%.”
Georgieva et al (2005) showed that using the sunspot number alone as an indicator of solar forcing resulted in good correlation with temperature until around 1980. “Solar activity, together with human activity, is considered a possible factor for the global warming observed in the last century. However, in the last decades solar activity has remained more or less constant while surface air temperature has continued to increase, which is interpreted as evidence that in this period human activity is the main factor for global warming. We show that the index commonly used for quantifying long-term changes in solar activity, the sunspot number, accounts for only one part of solar activity and using this index leads to an underestimation of the role of solar activity in the global warming in the recent decades. A more suitable index is geomagnetic activity which reflects all solar activity, and is highly correlated to global temperature variations in the whole period for which we have data.” “The geomagnetic activity reflects the impact of solar activity originating from both the closed and open magnetic field regions, so it is a better indicator of solar activity than the sunspot number which is related to only closed magnetic field regions.”
The authors propose that there are three “mechanisms for solar influence on climate:
1. variations in the total solar irradiance leading to variations in the direct energy input into the Earth’s atmosphere (Cubasch and Voss 2000):
2. variations in solar UV irradiance causing variations in stratospheric chemistry and dynamics (Hood 2003):
3. variations in solar wind modulating cosmic ray flux which affects the stratospheric ozone and small constituents (Veretenenko and Pudovkin 1999) and/or the cloud coverage (Svensmark and Friis-Christensen 1997), and thus the transparency of the atmosphere.”
The authors conclude: “So the sunspot number is not a good indicator of solar activity, and using the sunspot number leads to the under-estimation of the role of solar activity in the global warming.”
So there is a lot of information out there that confirms a significant warming impact from solar variation (maybe not enough to account for all the observed warming, but much higher than that assumed by IPCC with its admitted “low level of scientific understanding”). These studies also “shoot down” the Wikipedia graph you posted.
The estimated solar impact on 20th century warming in the various studies varies from less than 0.1C to a major part of the total observed warming. If we take the average estimate from all the studies, we arrive at a rise in the average total solar irradiance of about 1.65 W/m² over the 20th century, which yields a solar increment to 20th century warming of 0.35C. This would seem to be a reasonable estimate.
So we have in summary for the period 1901-2000:
0.24C warming from CO2, 0.08C warming from CH4 and 0.35C warming from solar, for a total of 0.67C (compared to an observed warming of 0.65C). Not bad.
This would indicate that around half of the observed 20th century warming came from GHGs (primarily anthropogenic) and the other half from natural solar variability.
It would also raise some serious questions regarding the validity of the assumed positive feedbacks, since the total observed warming can be explained without complicating matters by adding in these theoretical but totally unproven net positive feedbacks.
Max
Links 1:
IPCC SPM 2007
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf
Links 2:
Solanki et al.
http://cc.oulu.fi/~usoskin/personal/nature02995.pdf
http://www.ncdc.noaa.gov/paleo/pubs/solanki2004/solanki2004.html
Links 3:Ponyavin et al.
http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76.1026I.pdf
Links 4:
Usoskin et al.
http://www.agu.org/pubs/crossref/2006/2006GL025921.shtml
Links 5:
Geerts and Linacre
http://www-das.uwyo.edu/~geerts/cwx/notes/chap02/sunspots.html
Links 6:
Willson
http://www.earthinstitute.columbia.edu/news/2003/story03-20-03.html
Resending Links 6:
Willson
http://www.earthinstitute.columbia.edu/news/2003/story03-20-03.html
Links 7:
Soon et al.
http://oldfraser.lexi.net/publications/books/g_warming/solar.html
Links 8:Dietze
http://www.john-daly.com/fraction/fraction.htm
Links 9:
Lockwood and Stamper
http://www.wdc.rl.ac.uk/wdcc1/papers/grlcover.html.
Links 10:
Gérard and Hauglustaine
http://www.int-res.com/articles/cr/1/c001p161.pdf
Links 11:
Georgieva et al.
http://sait.oat.ts.astro.it/MSAIt760405/PDF/2005MmSAI..76..969G.pdf
Looks like Link 6 got “lost”:
Willson
http://www.earthinstitute.columbia.edu/news/2003/story03-20-03.html
See: http://www.guardian.co.uk/environment/2008/jun/23/fossilfuels.climatechange
Watch out, Tony – you may be next.
Max,
You wrote in part in your #81:
“Now to your question “Is it the sun?” Duh! What drives our climate on this planet? Black Wallaby’s SUV or the sun? Get serious, David. I believe you are an engineer, so you should be able to figure out some basic facts.”
I’m upset! I thought David was a physicist, in which case he could be excused for flights of fantasy, like parallel universes and stuff. I even wondered if he may have popped-up through a worm-hole somewhere. But, you shock me when you say he may be an engineer.
I feel embarassed for my profession!
BTW, I don’t own an SUV, but do have a large camper-van with an economical 2.4 litre diesel engine +5 Speed Man.