New paper in GRL confirms link between sun and clouds on global scale

[Wagmc]

The major conclusion: “A link between the Sun, cosmic rays, aerosols, and liquid-water clouds appears to exist on a global scale…”

http://docs.google.com/gview?a=v&q=cache:k3yiHsNVc1cJ:www.wzforum.de/forum2/file.php%3F0,file%3D11877

keep in mind that solar modulation of clouds of even 2-3 percent will account for all warming seen since 1900. No CO2 required...

 

[Skyhunter]

If there is such a link... then why during the current low solar minimun and associated increase in GCRs penetrating to lower altitudes, are temperatures still at record highs?

 

[Xnn]

... keep in mind that solar modulation of clouds of even 2-3 percent will account for all warming seen since 1900.

VERY WRONG!

The problem with the quoted statement is that cloudiness has actually been on the increase.
The increase in cloud cover has changed the Earth's albedo and actually decreased the
amount of sunlight reaching the Earth's surface. This has resulted in about
a loss of 1 kw/m^2 warming. In other words there has actually been a slight cooling
of the Earth due to the increase in clouds. If cloudiness had not increased, then
the amount of warming would have been greater than it has.

See page 136 of the following link:

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter2.pdf

All that the original paper has shown is that there has been a slight (2-3 sigma) and temporary decrease in low level clouds for a few days after the largest cosmic ray events. There has only been about 2 dozen of these events over the last 20 years and no real trend.

The long term influence of cosmic rays on the climate is minor and has been completely overwhelmed by the long term rise in greenhouse gases; primarily CO2 and CH4.

 

[Wagmc]

@ sky

Oceans hold a lot of heat. It is expected that changes in cloud cover will take 7-15 years to manifest themselves as atmospheric temperature changes.

And even though we are currently in an unusually deep and prolonged minimum, keep in mind that overall solar activity is still at a grand maximum compared to the previous 1,000 years. The five strongest solar cycles ever recorded have occurred in the last ~50 years. It is no surprise that temperatures remain high.

The fact that cycles 22 and 23 were less active than 21 - and that global temperatures have stabilized or probably cooled - should give one pause when considering CO2 as the main driver of global temperatures. 24 will tell this tale, no?

@Xnn

The importance of this paper is that is provides evidence of a direct, observable and measureable link between solar magnetic activity and cloud cover. That solar magnetic activity varies in conjunction with other solar parameters (TSI) is well established. It is also clear that long-term variations in global cloud cover vary in time with these magnetic changes. What has been missing is a causal mechanism. This paper is an important step in tht direction.

You seem to hold to the belief that whatever the IPCC says is written in stone and not subject to debate? That this study disagrees with the IPCC conclusion is irrelevant. New information invalidates old information. Observations always trump models. Whatever the IPCC said has now been shown to be incorrect.

Some other interesting reading. Many of these were not considered by the IPCC There are dozens more:

Shaviv, N. J., ( 2005). "On Climate Response to Changes in the Cosmic Ray Flux and Radiative Budget", JGR-Space, vol. 110, A08105.’

Scafetta, N., West, B.J. (2006). Phenomenological Solar Signature in 400 years of Reconstructed Northern Hemisphere Temperature Record”, GRL.

SOLANKI,S. K. and Fligge, M. 1998. Solar irradiance since 1874 revisited. Geophysical Research Letters, 25: 341-344.

SOLANKI, S.K., Usoskin, I.G., Kromer, B., Schüssler, M. and Beer, J. 2005. Unusual activity of the Sun during recent decades compared to the previous 11,000 years. Nature 436: 174 (14 July 2005) doi: 10.1038/436174b

Dergachev, V.A., Dmitriev, P.B., Raspopov, O.M. and Jungner, H. 2006. Cosmic ray flux variations, modulated by the solar and Earth's magnetic fields, and climate changes. 1. Time interval from the present to 10-12 ka ago (the Holocene Epoch). Geomagnetizm i Aeronomiya 46: 123-134.

Lockwood, M., and R. Stamper, 1999: Long-term drift of the coronal source magnetic flux and the total solar irradiance. Geophys. Res. Lett., 26, 2461-2464.

Perry, C.A., Evidence for a physical linkage between galactic cosmic rays ..., J. Adv. Space Res. (2007), doi:10.1016/j.asr.2007.02.079

Kirkby, J. 2008. Cosmic rays and climate. Surveys in Geophysics 28: 333-375.
Concludes: Numerous palaeoclimatic observations, covering a wide range of time scales, suggest that galactic cosmic ray variability is associated with climate change. The quality and diversity of the observations make it difficult to dismiss them merely as chance associations. But is the GCR flux directly affecting the climate or merely acting as a proxy for variations of the solar irradiance or a spectral component such as UV? Here, there is some palaeoclimatic evidence for associations of the climate with geomagnetic and galactic modulations of the GCR flux, which, if confirmed, point to a direct GCR-climate forcing. Moreover, numerous studies have reported meteorological responses to short-term changes of cosmic rays or the global electrical current, which are unambiguously associated with ionising particle radiation.

 

[CRGreathouse]

The five strongest solar cycles ever recorded have occurred in the last ~50 years. It is no surprise that temperatures remain high.

Give us some numbers to play with. How much heat do you attribute to a solar cycle -- say from the median to the most extreme of those five?

 

[Skyhunter]

It is expected that changes in cloud cover will take 7-15 years to manifest themselves as atmospheric temperature changes.

Where is this 7-15 year lag in the Svensmark's other claims to the GCR climate connextion?

Give me 8 years of leeway and I could find a correllation to almost anything.

As for the paper itself... 5 events and 26 data points?

http://www.atmos-chem-phys-discuss.net/8/13265/2008/acpd-8-13265-2008.html" that finds no correlation.

Abstract. The response of clouds to sudden decreases in the flux of galactic cosmic rays (Forbush decrease events) has been investigated using cloud products from the space-borne MODIS instrument, which has been in operation since 2000. By focusing on pristine Southern Hemisphere ocean regions we examine areas which are particularly susceptible to changes in cloud condensation nuclei (CCN) concentrations, and where a cosmic ray signal should be easier to detect than elsewhere. While previous studies on the subject have mainly considered cloud cover, the high spatial and spectral resolution of MODIS allows for a more thorough study of microphysical parameters such as cloud droplet size, cloud water content and cloud optical depth, in addition to cloud cover. Averaging the results from the 13 Forbush decrease events that were considered, no systematic correlation was found between any of the four cloud parameters and galactic cosmic radiation, with a seemingly random distribution of positive and negative correlations. When only the three Forbush decrease events with the largest amplitude are studied, the correlations fit the hypothesis better, with 8 out of 12 correlations having the expected sign. Splitting the area of study into several sub-regions, one sub-region in the Atlantic Ocean showed statistically significant correlations compatible with a cosmic ray-induced enhancement of CCN and cloud droplet number concentrations. However, the lack of correlation in any of the other 5 sub-regions suggests that this may be a statistical co-incidence. Introducing a time lag of a few days for clouds to respond to the cosmic ray signal did not change the overall results. Singling out low clouds of intermediate optical depth with large susceptibility did not lead to higher correlations. In conclusion, no response to variations in cosmic rays associated with Forbush decrease events was found in marine low clouds in remote regions using MODIS data.

 

[Xnn]

It is also clear that long-term variations in global cloud cover vary in time with these magnetic changes.

WRONG AGAIN!

Cloud cover has been increasing because increased levels of GHGs allow the atmosphere to hold more moisture. This has been the long term trend over the last 50 years.

Solar activity is currently at a 50 year minimum. If anything, the lack of solar activity should lead to less cloud cover. However, we are observing just the opposite. These solar theories have been shown repeatedly to lack significance.

Regarding the IPCC, if you take the time to actually read the report, you'll find that there are many areas of climate science where the level of understanding is low.

Wagmac; what you are proposing doesn't make sense or even agree with observations.

 

[Wagmc]

@Xnn: Solar activity is at a 50 year minimum, after a 1,000 year grand maximum. And you will note that temps are falling.

So you admit that cloud feedbacks from warming have been observed to be a net negative feedback. As opposed to positive feedbacks claimed by IPCC? But, I digress...

However, thank you for making my point. You have the solar influence exactly backward. A less active sun produces less magnetic protection, allowing more GCR to strike earth. More GCR means more clouds. Exactly what you say is occurring. Thus, the link is confirmed. Thank you.

In light of at least 35 studies in the last 5 years citing observation and measurement of a significant solar influence on climate, it is the CO2 driven warming theories that are demonstrating a lack of significance.

@Sky: Wigley (1988) found a 3-5 year lag. Hoyt & Schatten (2005) found the highest correlation with a 3 year lag. Scafetta & West (2003) put it at 6-12 years.

Again, Sky, you don't bother to even read the study. Svensmark references the flaws in Kristjnsson et al. directly. I won't even bother to address this further.

@ Greathouse:

Scafetta & West (2006) put the solar impact at least 50% of observed warming.

Pinker (2005) and Wild (2005) quantify changes in radiation reaching Earth's surface as increasing by 2.7 W/m2 and 4.4 W/m2 respectively, compared with the IPCC's estimate of greenhouse forcing of 2.4 W/m2. This puts the change in solar radiation at at least 50% of warming.

Beer (2000) puts it at 40%. Still almost half.

Scafetta & West (2008) ups their estimate to 70% solar.

And ALL these studies rely only on measures of TSI. NONE of them address indirect (magnetic) effects as studied by Svensmark. This will only serve to increase the amount of warming attiributable to solar changes.

 

[Skyhunter]

@Xnn: Solar activity is at a 50 year minimum, after a 1,000 year grand maximum. And you will note that temps are falling.

Please note that temps are not falling. The last decade is the warmest decade in the instumental record, and last month was the second warmest June on record, with SSTs being the warmest ever recorded for the month of June.

@Sky: Wigley (1988) found a 3-5 year lag. Hoyt & Schatten (2005) found the highest correlation with a 3 year lag. Scafetta & West (2003) put it at 6-12 years.

A 3 year lag, a 6-12 year lag or a 7-15 year lag. Such a huge disparity brings all the estimates into question. But since TSI peaked in 1960, none of them explain the 59+ years warming trend.

Again, Sky, you don't bother to even read the study. Svensmark references the flaws in Kristjnsson et al. directly. I won't even bother to address this further.

No need to cast aspersions against me. I did read the eight page study you linked. They mention Kristjnsson once on page three to acknowledge that Kristjnsson did not find a correlation. How you can interpret that as addressing flaws is beyond me.

The paper is very short on details or explanations. It appears that they looked for, and found a correlation to fit their argument with little to no explanation as to why these are the expected results. They do not go into detail as to why the filtering they used provides a robust analysis or why the lag between FD and CWC, or how these tiny aerosols become CCN. Since a clouds lifetime is measured in hours I fail to see how these FD events can be linked to CWC a week later, especially wihout considering the weather patterns during the 7 day interval.

It is an interesting paper, but very short on details. It is only a confirmation of the cloud GCR link to one who already has a bias in need of confirmation.

Pinker (2005) and Wild (2005) quantify changes in radiation reaching Earth's surface as increasing by 2.7 W/m2 and 4.4 W/m2 respectively, compared with the IPCC's estimate of greenhouse forcing of 2.4 W/m2. This puts the change in solar radiation at at least 50% of warming.

Apples and oranges. Surface flux is more a function of aerosols and related more to atmospheric composition than solar flux. You are misapplying these papers to make claims the authors do not.

And ALL these studies rely only on measures of TSI. NONE of them address indirect (magnetic) effects as studied by Svensmark. This will only serve to increase the amount of warming attiributable to solar changes.

As I pointed out Pinker and Wild are not measuring TSI, they are measuring surface flux not radiative forcing, so we can right away discard those studies as supporting your premise.

The change in TSI from the Maunder Minimum to the Modern Maximum is ~.2%. So (340Wm² x 0.02 = 0.68Wm²) It is impossible for such small fluctuations in the solar constant alone to account for the warming of the last 50 years.

 

[Andre]

last month was the second warmest June on record, ...

That may not be the general impression

 

[Xnn]

The combined global land and ocean surface temperature was the second warmest on record in June, behind 2005, and tied with 2004 as the fifth warmest on record for the year-to-date (January-June) period. The global ocean had the warmest June on record. The ranks found in the tables below are based on records that began in 1880.

http://www.ncdc.noaa.gov/sotc/?report=globalOceans temperatures were at all time highs for the Month of June with 2005 as the second warmest.

Land temps were the 6th warmest; the warmest being June 2005.

 

[Saul]

WRONG AGAIN!

Cloud cover has been increasing because increased levels of GHGs allow the atmosphere to hold more moisture. This has been the long term trend over the last 50 years.

Solar activity is currently at a 50 year minimum. If anything, the lack of solar activity should lead to less cloud cover. However, we are observing just the opposite. These solar theories have been shown repeatedly to lack significance.

Regarding the IPCC, if you take the time to actually read the report, you'll find that there are many areas of climate science where the level of understanding is low.

Wagmac; what you are proposing doesn't make sense or even agree with observations.

Cloud cover has been decreasing in the later part of the 20th century not increasing based on observations, not GHG models. This finding is supportive of Palle's papers on Earth'shine and satellite based planetary cloud cover analysis.

As the solar magnetic cycle appears to be interrupted (GCR is now increasing and I would assume as there are blue spots in the ocean surface temperature data, there is in response to increasing GCR, increasing cloud cover over the ocean which is ion poor.) we will be able to determine by observation how much of the 20th century warming was due to decreased cloud cover and how much was due to GHG.


http://www.atmos-chem-phys.org/5/1721/2005/acp-5-1721-2005.html

Analysis of the decrease in the tropical mean outgoing shortwave radiation at the top of atmosphere for the period 1984–2000

All cloud types show a linearly decreasing trend over the study period, with the low-level clouds having the largest trend, equal to −3.9±0.3% in absolute values or −9.9±0.8% per decade in relative terms. Of course, there are still some uncertainties, since the changes in low-level clouds derived from the ISCCP-D2 data, are not necessarily consistent with changes derived from the second Stratospheric Aerosols and Gas Experiment (SAGE II, Wang et al., 2002) and synoptic observations (Norris, 1999). Nevertheless, note that SAGE II tropical clouds refer to uppermost opaque clouds (with vertical optical depth greater than 0.025 at 1.02μm), while the aforementioned synoptic cloud observations are taken over oceans only. The midlevel clouds decreased by 1.4±0.2% in absolute values or by 6.6±0.8% per decade in relative terms, while the high-level ones also decreased by 1.2±0.4% or 3±0.9% per decade in relative terms, i.e. less than low and middle clouds. Thus, the VIS/IR mean tropical (30_ S–30_ N) low-level clouds are found to have undergone the greatest decrease during the period 1984–2000, in agreement with the findings of Chen et al. (2002) and Lin et al. (2004).

 

[Skyhunter]

That may not be the general impression

This is science not politics. Perception is not reality.

 

[Andre]

look again

 

[Wagmc]

GISS is the only measure that reports still increasing temperatures. It has been well established that their land measurements are contaminated by UHI. GISS is the outlier.

Reading any of the other three major temperature measures gives a completely different picture.

A 3 year lag, a 6-12 year lag or a 7-15 year lag. Such a huge disparity brings all the estimates into question

You are free to publish a rebuttal.

As I pointed out Pinker and Wild are not measuring TSI, they are measuring surface flux not radiative forcing, so we can right away discard those studies as supporting your premise.

You are making a strawman argument. I provided a list of studies that present measures of changes in solar activity related to changes in global temperature. "What" a particular study is measuring is less relevant than the fact that continued observations indicate that yes, solar activity does change and, yes, it is a major driver of global temperatures.

The change in TSI from the Maunder Minimum to the Modern Maximum is ~.2%. So (340Wm2 x 0.02 = 0.68Wm2) It is impossible for such small fluctuations in the solar constant alone to account for the warming of the last 50 years.

Since prior to 1940 the ONLY source of changes in global temperature were these "small fluctuations," it would appear on first examination that your claim of "impossiblity" is incorrect. There could be no other cause, therefore these small changes MUST influence temperature.

Second, the studies previously referenced present evidence that contradicts you.

Third, you continue to ignore that UV varies as much as 6% and has recently implicated in ozone destruction (an exothermic process). Likewise, TSI does not measure indirect, magnetic effects, which was the subject of the OP. These indirect effects will be in addition to changes in TSI.

The continued increase in temps since the solar peak "50 years ago" is another strawman. You will note that the relatively weak cycle 20 was associated with "the cooling 70's." It was followed by three of the five strongest cycles ever recorded. That temperatures continued to rise is no surprise. If you turn the burner to high, and then turn it down to medium the pan will continue to warm if it had not reached equilibrium before you turned down the heat. physics 101.

 

[Skyhunter]

look again

Look at what? A bunch of blogs?

No thanks.http://www.ncdc.noaa.gov/sotc/?report=global" where real science is conducted.

Based on preliminary data, the globally averaged combined land and sea surface temperature was the second warmest on record for June and the January-June year-to-date tied with 2004 as the fifth warmest on record.

 

[Andre]

Cloud cover has been decreasing in the later part of the 20th century not increasing based on observations, not GHG models. This finding is supportive of Palle's papers on Earth'shine and satellite based planetary cloud cover analysis.

Here is one of those papers.

here are figs. one and two respectively showing the global cloud cover and the correlation with the albedo fluctuation measured on the reflection of the dark side of the moon.

They note the trend reversal around 1998-1999 and hence wonder...

Can Earth’s Albedo and Surface Temperatures Increase Together?

as obviously the higher the albedo the more visible light is reflected and the lower the temperatures. They do some proposals however they fail to do the obvious and that is to compare the albedo trend with the actual global temperature trend. That would have revealed that the temperature trend also changed in the same period and I bet we would find a very nice correlation between actual temperatures and actual measured albedo if it was allowed here to show some own work.

and temperatures corrolating with global albedo would again take some explaining away from other factors like greenhouse effect for instance.

 

[Skyhunter]

GISS is the only measure that reports still increasing temperatures. It has been well established that their land measurements are contaminated by UHI. GISS is the outlier.

Reading any of the other three major temperature measures gives a completely different picture.

Where do you get your information from?

http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts+dSST.txt"

http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3vgl.txt"

http://www.ncdc.noaa.gov/sotc/?report=global"

And UHI contamination is not "well established", it is a specious argument propagated on denier blogs, completely unsupported by any credible source that is allowed on this forum.

You are free to publish a rebuttal.

Is this how you address arguments you cannot rebut? Are you afraid to address the disparity?

You are making a strawman argument. I provided a list of studies that present measures of changes in solar activity related to changes in global temperature. "What" a particular study is measuring is less relevant than the fact that continued observations indicate that yes, solar activity does change and, yes, it is a major driver of global temperatures.

I am doing no such thing. I simply pointed out that surface flux is not radiaive forcing and therefore does not support your premise.

Since prior to 1940 the ONLY source of changes in global temperature were these "small fluctuations," it would appear on first examination that your claim of "impossiblity" is incorrect.

Are you suggesting that volcanic eruptions, land use changes, continental drift, orbital oscillations and the thermal structure of the atmosphere have no effect?

I offered a simple equation that supports my argument that fluctuations in the solar constant alone can not account for large variations in radiative equillibrium.

There could be no other cause, therefore these small changes MUST influence temperature.

That is a bit narrow minded of you. I am sure that every scientist you quote would disagree with that statement.

Second, the studies previously referenced present evidence that contradicts you.

Your opinion. And your opinion unsupported by evidence or argument is just your opinion.

Third, you continue to ignore that UV varies as much as 6% and has recently implicated in ozone destruction (an exothermic process).

How can I ignore it if you don't present it in your argument?

Likewise, TSI does not measure indirect, magnetic effects, which was the subject of the OP. These indirect effects will be in addition to changes in TSI.

It was not the OP, but it was the subject of your latest premise. I addressed the OP and you ignored my rebuttal.

The continued increase in temps since the solar peak "50 years ago" is another strawman. You will note that the relatively weak cycle 20 was associated with "the cooling 70's." It was followed by three of the five strongest cycles ever recorded. That temperatures continued to rise is no surprise. If you turn the burner to high, and then turn it down to medium the pan will continue to warm if it had not reached equilibrium before you turned down the heat. physics 101.

I am ignoring nothing. I have addressed every point you made.

And your argument is internally contradictory. If the cooling during the 70's was a response to cycle 20... then by implication the climate reached equillibrium in the 70's. And since most researchers agree that the cooling in the 70's was a direct result of increased aerosols from human activity... well what can I say. You seem to ignore everything that contradicts your belief.

I guess this is why you need to have a climate response to solar forcing of 3 to however many years it takes to confirm your bias.

 

[sylas]

Why do you have to lie?

I want to make this a public comment, as a kind of friendly fire.

This is a really contentious topic area, and there are going to be inevitably some strong comments made. It's also a very hard area for our mentors to work with. Let's make their job easier for them.

Direct personal attacks like this on a fellow contributor to the forums is going to be a problem. There are all kinds of reasons one might have the wrong idea -- and I agree with you completely that the comment on temperature tends was false, and easily seen to be false by looking at available temperature records.

But there is one heck of a lot of really atrocious information out there. And there is a difference between saying an individual is <pejorative descriptor> and saying an idea is <pejorative descriptor>. It's possible to repeat bad information without being a liar. This is common in this debate topic. I don't generally know precisely HOW people come to various ideas here, either good or bad. So let's just stick to what is wrong with the ideas themselves, as far as possible.

If you have a strong case that someone is actually lying, or disruptive, or whatever -- and this can happen -- then I suggest we report it and let the mentors manage it. Or else perhaps just ignore for the first couple of times.

Sorry to single you out -- I do it because I'm so obviously on "your side" on pretty much everything else, so you hopefully won't mind. I want to this go public as a comment from a non-mentor working through how to engage most constructively.

Cheers -- sylas

 

[Skyhunter]

You are correct Sylas. I edited my post.

I do know however that wagmc has made this claim before and been shown that it is false, yet he continues make it without any supporting evidence. Just like the claim that the land record is invalid because of UHI effect.

 

[Wagmc]

There are three global measures, not contaminated by UHI, that present an opposite conclusion. You stick with NOAA because it supports your beliefs. That's not science.

 

[Skyhunter]

There are three global measures, not contaminated by UHI, that present an opposite conclusion. You stick with NOAA because it supports your beliefs. That's not science.

I am not excluding any surface temperature record. They all are statistically the same.

You are the one who wants to discard first order evidence (the instumental record) based on a specious argument drummed up on denier blogs.

Before you throw up UAH and RSS, remember this;

1. Tropospheric temperatures are not surface temperatures.
2. The OP paper in the last thread you started found a 7 month lag in surface to troposphere anomalies.

 

[Wagmc]

NOAA:

August 10, 2009

The July 2009 temperature for the contiguous United States was below the long-term average, based on records going back to 1895, according to a preliminary analysis by NOAA’s National Climatic Data Center in Asheville, N.C.

So that makes it like the...uh...12th warmest in 30 years?

My oh my what would temperatures be without un-adjusted UHI?

Meanwhile, Global SST anomalies dropped slightly in July to +0.28 deg C, so the oceans are cooling.

And this during northern hemisphere summer, when the planet generally warms due to most of the landmass located in the north. While the southern oceans shed heat during winter.

 

[Skyhunter]

NOAA:

August 10, 2009

The July 2009 temperature for the contiguous United States was below the long-term average, based on records going back to 1895, according to a preliminary analysis by NOAA’s National Climatic Data Center in Asheville, N.C.

So that makes it like the...uh...12th warmest in 30 years?

My oh my what would temperatures be without un-adjusted UHI?

Meanwhile, Global SST anomalies dropped slightly in July to +0.28 deg C, so the oceans are cooling.

And this during northern hemisphere summer, when the planet generally warms due to most of the landmass located in the north. While the southern oceans shed heat during winter.

This is a red herring. The contiguous US is less than 2% of the Earth's surface, yet you consider it as evidence to support your bias. A slight drop in SST over a month, and you declare ocean cooling.

Can you really not see how this demonstrates an extreme confirmation bias?

 

[Wagmc]

But the US is >20% of landmass at our latitude band.

And the US represents 50% of temperature sensors. And if our "best in the world" sensors are affected by UHI, imagine what the rest of the world is like.

I'll admit confirmation bias when you do... you continue to ignore alternate temperature measures that refute GISS. Even HadCrut is cooler, and it measures surface, not satellites.

 

[sylas]

But the US is >20% of landmass at our latitude band.

And the US represents 50% of temperature sensors. And if our "best in the world" sensors are affected by UHI, imagine what the rest of the world is like.

I'll admit confirmation bias when you do... you continue to ignore alternate temperature measures that refute GISS. Even HadCrut is cooler, and it measures surface, not satellites.

Differences between HadCRUT and GISS are very small, and completely negligible over the USA. You would have to calculate that for yourself from the grid datasets, but it is entirely possible. You are simply wrong here.

In fact, the USA is a good test case for testing how Urban Heat Island effects are managed, because there are so many available stations. The impact of heat island effects is small, and compensations are explicit in both the GISS and the HadCRUT analysis. Most of the temperature sensors used for these datasets are not in significant heat islands; and it is also entirely possible to repeat the whole USA analysis using only rural stations. I've done it myself, as an exercise, and I think it has been done professionally as well, though I am away from home at present and have not taken the time to chase up the references. The result of this analysis is that you get pretty much exactly the same result when you use only rural stations over the continental USA.

There are differences between HadCRUT and GISS over the whole globe; the reason for this has nothing to do with heat islands; it is mainly to do with how the two datasets extrapolate to regions with low coverage, especially the Arctic... where you don't have any heat island effect. Ironically, it turns out that the higher results from GISS that you mention are almost entirely because GISS is using more information from regions with NO heat island effect!

Both GISS and HadCRUT measure the surface, using surface temperature records.

Such differences that exist are small, and tend to cancel out over longer time periods of several decades.

You have given no reason to suggest Skyhunter is ignoring anything. He's the one who has cited more temperature records, and he's correct that they give similar results, within the published error bars.

Cheers -- sylas

 

[Wagmc]

First, to completely ignore a set of data (satellite temperature records) that present a different conclusion than surface records is not how true science is done. The difference needs to be explained. Sky cites land based records. He simply ignores satellite records.

Differences between HADCrut and GISS over the globe are not insignificant, and are increasing.

One reason for the increasing difference between the surface and satellite temperature trends may be that one of them is incorrect. It is certainly the simplest answer.

There have been several published studies that indicate that UHI is real, is significant, is not properly being adjusted for, and is creating an artificial warming trend in the surface record.

A spurious warming introduced into the surface temperature trend from UHI that occurs in most of the places where land-surface air temperature measurements are made has been observed. There is a substantial scientific basis that refutes your claim that UHI is insignificant.

McKitrick and Michaels (2004) make a strong argument when they regress surface temps in 93 countries and find that GISS data are significantly correlated with economic growth activity (like building factories and airports, which all contribute to UHI)

Delaat (2004) and again in (2006) likewise found that high growth areas have greater warming than low growth areas.

Might also want to read up on Kalnay (2003) and Gallo (1999)

 

[Andre]

http://www.cru.uea.ac.uk/cru/data/temperature/hadcrut3vgl.txt"

Are you sure?

1996 0.067 0.244 0.125 0.095 0.176 0.161 0.178 0.176 0.092 0.087 0.080 0.175 0.138
1996 83 83 83 80 79 80 80 80 81 80 80 82
1997 0.157 0.244 0.260 0.198 0.255 0.365 0.373 0.404 0.455 0.482 0.448 0.527 0.347
1997 82 82 82 81 81 80 80 81 80 79 80 81
1998 0.484 0.732 0.519 0.602 0.567 0.576 0.650 0.612 0.399 0.406 0.343 0.426 0.526
1998 81 81 81 79 80 78 79 79 78 79 79 80
1999 0.363 0.534 0.286 0.318 0.246 0.266 0.281 0.251 0.274 0.239 0.223 0.341 0.302
1999 80 80 80 79 78 78 78 80 79 80 80 81
2000 0.212 0.361 0.332 0.445 0.267 0.249 0.260 0.337 0.310 0.210 0.159 0.183 0.277
2000 82 82 80 79 78 78 77 79 77 78 78 79
2001 0.329 0.289 0.474 0.426 0.399 0.416 0.453 0.498 0.403 0.376 0.489 0.323 0.406
2001 79 80 80 78 77 78 78 80 78 78 79 80
2002 0.570 0.594 0.586 0.443 0.432 0.458 0.462 0.412 0.412 0.362 0.398 0.327 0.455
2002 79 81 81 79 79 77 78 79 78 79 81 80
2003 0.515 0.424 0.415 0.404 0.437 0.435 0.454 0.511 0.497 0.549 0.418 0.517 0.465
2003 80 80 80 79 78 79 79 80 80 79 80 82
2004 0.496 0.560 0.500 0.484 0.322 0.350 0.381 0.420 0.443 0.467 0.520 0.382 0.444
2004 81 82 80 79 79 79 78 79 79 78 79 81
2005 0.452 0.360 0.489 0.532 0.474 0.506 0.531 0.498 0.494 0.501 0.489 0.369 0.475
2005 80 81 80 78 78 79 80 81 81 80 81 82
2006 0.298 0.431 0.384 0.364 0.349 0.447 0.446 0.478 0.421 0.473 0.435 0.529 0.421
2006 81 82 83 81 80 81 81 81 82 82 81 82
2007 0.622 0.509 0.437 0.467 0.372 0.373 0.392 0.362 0.401 0.361 0.263 0.230 0.399
2007 81 81 81 81 80 81 81 82 82 81 81 82
2008 0.050 0.199 0.478 0.285 0.282 0.312 0.405 0.403 0.370 0.446 0.398 0.335 0.330
2008 82 83 84 83 82 82 82 83 83 83 82 82
2009 0.371 0.361 0.364 0.391 0.392 0.494 0.000 0.000 0.000 0.000 0.000 0.000 0.395
2009 81 82 81 78 79 79 0 0 0 0 0 0

 

[Wagmc]

another new paper in GJR today directly addresses UHI contamination of surface measures.

http://www.agu.org/journals/pip/jd/2009JD011841-pip.pdf

concludes:

We find that there have, in general, been larger linear trends in surface temperature datasets such as the NCDC and HadCRUTv3 surface datasets when compared with the UAH and RSS lower tropospheric datasets, especially over land areas. This variation in trends is also confirmed by the larger temperature anomalies that have been reported for near surface air temperatures (e.g., Zorita et al., 2008; Chase et al., 2006; 2008, Connolley, 2008). The differences between surface and satellite datasets tend to be largest over land areas, indicating that there may still be some contamination due to various aspects of land surface change, atmospheric aerosols and the tendency of shallow boundary layers to warm at a greater rate [Lin et al., 2007; Esau, 2008; Christy et al., 2009].

We conclude that the fact that trends in thermometer-estimated surface warming over land areas have been larger than trends in the lower troposphere estimated from satellites and radiosondes is most parsimoniously explained by the first possible explanation offered by Santer et al. [2005]. Specifically, the characteristics of the divergence across the datasets are strongly suggestive that it is an artifact resulting from the data quality of the surface, satellite and/or radiosonde observations.

 

[Skyhunter]

My mistake Andre.

I missed the 0.5##'s. Maybe I should not try and decipher charts on a laptop under daylight conditions.

My point is still valid however, since all three records are within small margins of one another.

Wagmc,

I have always admitted a confirmation bias. It is a natural human instinct to be biased, we naturally want our beliefs to be true. It is only through recognition of our own bias that we can expand our knowledge.

Tropospheric temperatures lag surface temperatures. You yourself have cited literature that suggests the lag is 7 monthes. I recall that earlier research suggested 3-5 monthes, but I don't remember where I read it. I'll try and find a reference. My point is that the temperature of the atmosphere is not necessarily indicative of surface temperatures. Primarily because the temperature of the troposphere by itself is not a first order measure of atmospheric energy content. The atmosphere expands as it warms, increasing the height of radiative equillibrium. In other words it is not the temperature itself, but the height at which thermal emission equals absorption. The surface temperature can be calculated by the lapse rate. The higher this equllibrium is achieved, the warmer the surface.