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Neven, hi,
They make an interesting point. In my words, SO2 shouldn’t be at the focal point of our efforts, but CO2. Unfortunately, restrictions on SO2 emissions are technically and economically easy and don’t cut at the roots of our precious market-economy. CO2 reduction does (at least, for the Scrooge-characters). We’ll see to what extent tjis matters in the upcoming climate summit.

 photo 2015 11 27 Hans met klimaatmoment small_zpsoqdkw8fm.jpg

This is me on a local campaign, holding a message for the summit: "my town cuts emitting CO2"


Go, Schiedam! :-)

Seke Rob

Less of the (air) pollutants implicitly has a precursor in less CO2 emission, or is that a mistaken 'assumption'?


I believe it depends on how it's done. If they use scrubbers to take the SO2 out, there won't be a similar reduction in CO2.

Bill Fothergill

Expanding on Neven's point, China is having some interesting times at present in terms of atmospheric aerosols. See this BBC article...

If they (ie China) continue with their increasing investment in coal-powered generation of electricity, whilst simultaneously putting a commensurate effort into reduction of particulate pollution, we're going to have a further increase in radiative forcing.

I do understand that China is supposed to be trying to lead the way in terms of CCS (Carbon Capture and Storage) but this technology is still in its infancy.

For those unfamiliar with CCS, have a look at the wiki entry, or here...

Rob Dekker

Bill, one would hope that the Chinese, as well as the rest of us, would choose to kill two birds (SO2 and CO2) with one stone : Abandon coal, and replace with renewables.

It's not that the Chinese do not have an economical incentive. After all, the cheapest solar cells are manufactured in China ($0.25 ct/Watt on Alibaba).


The cheapest solar cells are very expensive for the average Chinese citizen who manufactures them, I am afraid . . .

Bill Fothergill

Rob, amen to what you said.

However, the following (IMO) is probably a very incomplete list of just a few of the main barriers ...

1) Coal is far and away the most abundant form of fossil fuel. (Let's have a big round of applause for the Carboniferous Period.)

2) Aerosol scrubbers and CCS technologies all add to the Capital Cost of power plants.

3) These "clean-up" technologies themselves consume energy, and therefore the kW/hrs per tonne of fuel ratio goes down at the same time as the running costs go in the opposite direction.

4) The whole "CO2 as the pre-eminent driver of climate change debate" is just about the single best example of the tragedy of the commons. I really fear what will be in store over the forthcoming decades.

One possible step in the right direction could be coming out of CoP21 in Paris, with India signalling possible willingness to reassess its planned coal power plant program, with the quid pro quo coming in the form of financial help with investment in a renewables program. See this brief BBC article... http://www.bbc.co.uk/news/science-environment-34989719

karen stabenow

Interesting news from Guardian UK on methane leak in California.



Yet another downtick yesterday according to the ADS-NIPR standards, minus 907 km2.

As a consequence yesterday on the 5th of December the year 2015 had by a smallish margin the lowest area ever since satellite observations began ...

Bill Fothergill


you are misinterpreting the default display of the ADS (VISHOP) chart. When this opens, it currently shows just 6 time series: the average values for the 1980's, 1990's, and 2000's, as well as the values for 2012, 2007 and 2015. These last three represent (in that order) the 3 lowest September daily minimums thus far recorded. Earlier this year, the plot would have shown 2012, 2007, 2011 and 2015, i.e. the 3 lowest September minima plus the current year. That changed when 2015 ousted 2011 as 3rd lowest on the ADS metric, and the display dropped from 7 to 6 time series.

To see the plot for each year from 2002 onwards, one must first click on the large pink rectangle below the plot area. (NB Rather confusingly, the text reads... "sea ice extent change of each year since 2000".)

By this particular metric for both the 5th and 6th of December, 2015 is languishing way back in 3rd lowest place, behind 2006 and 2010.


Bill Fothergill wrote:

... you are misinterpreting the default display...

Yep, and I stand corrected.

Bill Fothergill

@ Vaughn,

By no stretch of the imagination is China alone in having to face this stark reality...

The embedded link to the Hindustan Times contained within the Guardian article makes for equally depressing reading.

Bill Fothergill

Oops, I hit "post" instead of "preview".

There is a real-time Air Quality monitoring app which anyone can easily access. This link is for the US Embassy in New Delhi...

One of the nearby locations logged a jaw-dropping AQI value of 999 on the 8th December.

Here is a link to the basics of the Air Quality Index...

That gives some idea of how far off the scale a value of 999 represents.



Burning coal has caused these kinds of problems for years. Maybe if half a million people drop dead in on spot it will wake the world up. You have probably seen this article about London in 1952 before but maybe you will still find it of interest:



Bill, I checked your links. That is horrible for India...and they want to still burn coal????? I don't exactly get it!

Thanks for the Air Quality scale etc.

Bill Fothergill


Thanks for the memory-jolter concerning London's 1952 Great Smog. (Or possibly Smaug?)

As I lived north of the border until 1975, I did not experience it personally, but there were some crackers in Glasgow as well. Round about 1959 or 60, I remember stumbling my way to primary school and having to more or less hold on to fences and hedges for the entire distance. This was to avoid becoming lost on a totally familiar route.

There was - fortunately - only one major road crossing. That, however, was an absolute nightmare, as any vehicle on the opposite side of the road was rendered invisible owing to the muck in the air. In order to cross safely, hearing had become more important than sight.

Just after I started to cross, I heard an engine noise and could just about discern what I took to be the headlights of two approaching motorcycles. For a brief moment of madness, I considered standing still, as it looked as though they would pass on either side of me. However, I rejected this idea and quickly stepped back to the kerbside.

That transpired to have been a rather wise decision, as about one second later, these two "motorcycles" resolved themselves into one, extremely solid, double-decker bus - which, in addition to its headlights, had every internal light switched on as well.

In those days, every single person I knew had their home heated by an open coal fire. The boiler at the school was also coal fired, as were the trains, and the steelworks, etc, etc.


Bill, great story. You are dating yourself; I was born in 1952. Some of my family(Eatch) lived and worked in Sheffield at the Sheffield Steel Works I believe it was called(Please correct me if I am wrong on the name.) That was back in the late 1800s. The story I heard was about how nasty it was to work there because of the smoke and fumes.

Cato Uticensis

I understand this is a late comment, but the subject is interesting. Would just like to provide an example from the place where I live, the north of Italy, Po Valley.

Until about 15 years ago we used to have very thick fogs in winter, thermal inversions and very low temperatures associated, over quite a vast area (the Po Valley extends over the whole northern Italy, surrounded by Alps and Apennines mountains).

After the fuel oil was abandoned for use in heating systems and the introduction of sulphur removal processes the situation has improved dramatically in terms of pollution and, therefore, formation of fog.

This has led to clearer skies, much more insulation and, overall, a consistent increase of maxima temperatures in winter over quite a vast geographical area. In other terms, environmental friendly policies have ultimately led to an increase of temperature.

Apparently a paradox, but just apparently, as I have read interesting papers talking about the existence of multiple local warmings leading to an overall global warming (heat island effect, the most commonly cited). This is exactly what has happened in northern Italy.

The climate has warmed up, this is fact.

But local warming can have played a significant role and, ironically, policies of pollution control, might have even provided a positive contribution to such warming, though at a local level.

Bill Fothergill

@ Cato " ... much more insulation ..."

Should that read "insolation"? Although much more insulation would certainly be beneficial.

Frighteningly, it might be starting to look a bit academic. The November Gistemp LOTI figures have just been published, and they make sobering reading. That's the second consecutive month with an anomaly >1 degree C.

Last year might have been a statistical tie with 2010, but the meteorological year December 2014 - November 2015 now stands approx 0.11 Celsius degrees ahead. The 2015 calendar year is now also certain to be around 1 tenth of a degree up on last year.


Cato Utensils,

I'll admit, that the Po Valley has historically not been a very healthy place to live. Apparently, people in the Po Valley and people in the central part of China have realized, that air pollution is not good for anything.

However, climate change is not only a local artefact. It is a genuine threat to us all. If you keep up your local pollution levels and scare the shit out of the kids from Syria, you may be able to keep up your own imaginations of the "good life". If, on the other hand, you all help to clear up the dirt you produce, you may be able to attract people from abroad, who will share your wisdom and make a series of benefits to your community.

It is your choice and you decide which way to go.

John Christensen


You may consider the point that air pollution is not a phenomenon restricted to the Po Valley and China.

It is also not new that reduction in sulphur dioxide levels have resulted in more days with clear skies and some warming in western and eastern Europe, as pointed out in this paper from 2010:


“Surface solar radiation has undergone decadal variations since the middle of the twentieth century, producing global ‘dimming’ and ‘brightening’ effects. These variations presumably result from changes in aerosol burden and clouds3, but the detailed processes involved have yet to be determined. Over Europe, the marked solar radiation increase since the 1980s is thought to have contributed to the observed large continental warming, but this contribution has not been quantified. Here we analyse multidecadal data of horizontal visibility, and find that the frequency of low-visibility conditions such as fog, mist and haze has declined in Europe over the past 30 years, for all seasons and all visibility ranges between distances of 0 and 8 km. This decline is spatially and temporally correlated with trends in sulphur dioxide emissions, suggesting a significant contribution of air-quality improvements. Statistically linking local visibility changes with temperature variations, we estimate that the reduction in low-visibility conditions could have contributed on average to about 10–20% of Europe’s recent daytime warming and to about 50% of eastern European warming. Large improvements in air quality and visibility already achieved in Europe over the past decades may mean that future reductions in the frequency of low-visibility events will be limited, possibly leading to less rapid regional warming.”

So there is an upside in the fact that some regions have made progress towards reduction in pollution levels and that therefore some of the temporary cooling provided by the pollution has been eliminated already.

John Christensen

Hi Bill,

Luckily the GISS temp data is not the topic of this blog.

The way the station data has been tampered with in the 'homogenization' process in v3 makes their temperature record utterly useless.

This is why something more substantial such as the Arctic sea ice is so much more interesting and relevant to observe and analyze.

Arctic Nev

Are you accusing people at GISS of fraud, John?



I’m fully aware that visibility has gone up in Europe since the mid 1970ies. I was just fed up with the insinuation made by our Italian friend, that global warming was the sum of regional artefacts.

Ever since I came across this paper: http://link.springer.com/article/10.1007/BF00866197 , which was openly sponsored by the German coal industry, I have had reservations about linking circulation changes, cloud cover and air pollution. This paper is in my view one of the worst attempt to whitewash air pollution.

In those days, the author tried to explain the increasing air pollution (i.e. reductions in the number of sunshine hours) over eastern Germany through some dubious circulation assumptions. I will leave it to you to read the full details behind the paywall.

As your own quote says: “…the detailed processes involved have yet to be determined.” and “… this contribution has not been quantified.”

To quote myself: ” It is your choice and you decide which way to go.”

John Christensen

Arctiv Nev,

Fraud is a strong word..

I have searched for years to find good scientific reasons for how GISS correct temperature records, unsuccessfully.

Example: Cuzco, Peru, a very nice and fairly isolated city in an altitude of about 3.400 meters.

GISS v2 (Used until 2011) Cuzco station temperature history :

GISS v3 (Current official GISS temps) Cuzco station temperature history (After 'GISS Homogeneity Adjustment'):

The adjustments made to historic temperatures are massive and have been made to many other local stations as well.

If you have any links to good explanations of why historic temperatures have been adjusted downward to this degree I would very much like to review. With the UHI one would think recent temperatures should be adjusted by the homogeneity analysis and not temperatures from 1940-1970, but that is not happening.

Arctic Nev
Fraud is a strong word..

So is 'tampering'. It implies that people do something on purpose to get a particular result. And because GISTEMP doesn't deviate strongly from other temperature data sets, it means that all of them have been 'tampered' with. It's a conspiracy. Now, why would someone want to imply that?

If we go that way, we might as well say that "something more substantial such as the Arctic sea ice" isn't "interesting and relevant to observe and analyze", because who knows how much all those area and extent data sets have been tampered with.

John Christensen


Yes, I did notice the insinuation as well.

The challenge to climatologists is that the areas covered best by temperature stations are the areas of high economic development, which means that air pollution started with the coal-based industrialization 150 years ago.
Programs to clean-up the air started in the early 70s with the advent of the environment movements, which then according to the article at the top of this thread can result in localized warming.
So, while some areas of Europe, US, and Japan can have experienced some warming due to this effect, other areas have become increasingly polluted.
For the climatologists building forecasting models, they need to take this effect into account, including assumptions on timing and level of economic development, and how fast different regions would move to cleaner economic activities.

John Christensen

So regarding the Cuzco example:

In GISS v2 (Non-homogenized data) the annual average temperature in 1959 was 13.0C.

In GISS v3 and homogenized the annual average temperature in 1959 is now 11.7C.

That is a reduction in the average annual temperature of 1.3C..

The reason I picked Cuzco is that this station is one of the longest records available in Peru, which means that data from this station is probably used to homogenize data from other stations up to 1200km from Cuzco.

As I said, if anyone can explain how actual temperature measurements over an entire year can be adjusted by 1.3C for a station, please let me know. I am not unwilling to learn.



can't you see it is somewhat counter-productive to blame the recent global warming on the environmental movements since the 1970ies?

The changes from wood to whale oil, coal to oil, gas to bitumen and bonfires to forest fires may have led to numerous regional changes in air pollution levels, which must also have been intimately linked to circulation changes.

To even think that climate modellers could include similar changes in their projections is a futile excercise similar to the one you are trying with the Peruvian time series.

John Christensen


I could be wrong, but it seems that climate modellers are starting to take these changes into their projections, which is the topic for this thread:

"Cleaner atmosphere means more Arctic sea-ice melt, study says"

Or maybe I missed your point?

For Cuzco, of course if nobody cares about a change of 1C or more in temperatures, then I am good with that also. Who cares, right?


That's right, nobody here cares. Maybe take it to WUWT or Steven Goddard's place. People really care about these non-issues over there.

John Christensen

Happy we are in agreement Neven.

Bill Fothergill

@ John C

"Luckily the GISS temp data is not the topic of this blog"

Very true. However, in common with most people, I think that the amount of Arctic Sea Ice (area, extent and volume) is a function of global temperatures. More specifically, there is an inverse relationship between these factors. Consequently, any significant variation in global temperatures is very likely to have a pronounced effect on the health of the Arctic ice. (Although there may very well be a lag before this becomes manifest.)


Interesting claim. Let's see if it stands up to any scrutiny shall we?

Rather than just use the surface temperature datasets, I've also included the UAH and RSS TLT's as well. Since the satellite datasets begin in 1979, I have calculated the decadal temperature gradients over the 36-year period 1979-2014 for the following 6 datasets...

NASA Gistemp (base period 1951-1980) = 0.16 celsius/decade

BEST (base period 1951-1980) = 0.17 celsius/decade

HadCRUT (base period 1961-1990) = 0.16 celsius/decade

NOAA/NCDC (base period 20th Century) = 0.15 celsius/decade

UAH TLT (base period 1981-2010) = 0.14 celsius/decade

RSS TLT (base period 1981-2010*) = 0.12 celsius/decade

(* NB RSS actually uses the 20 year base period of 1979-1998. However, NOAA does a rather neat little conversion (or "trick", for the conspiracy theorists amongst us) in order to give a side-by-side comparison with the UAH TLT data.
http://www.ncdc.noaa.gov/temp-and-precip/msu/time-series/global/lt/aug/ann )

The first 5 of these have a spread of only 0.3 degrees Celsius per CENTURY. Even including the somewhat outlying RSS data, the spread is still less than half a degree over a century.

How about the 2015 data?

In the BEST data, the three warmest calendar years thus far were 2014, 2010 and 2005. These were statistically tied with values of 0.647C, 0.646C and 0.644C respectively. The closest to these three was 2007 (0.598C), with 1998 languishing back in 9th place on 0.569C.
The latest rolling 12 month period in the BEST dataset (Oct 2014 - Sep 2015) has a value of 0.7C

For the HadCRUT data, there are four years that are effectively tied: 2014, 2010, 2005 and 1998. The values for each of these respectively are: 0.567C, 0.559C, 0.544C and 0.536C
The HadCRUT 2015 year-to-date value up to (and including) October is 0.713C

In the NOAA/NCDC dataset, the warmest years until now were 2014 (+0.74C), 2010 (+0.7C) and 2013 tied with 2005 on +0.66C.
The NOAA/NCDC rolling average for the latest 12 month period (Nov 2014 - Oct 2015) is standing at +0.85C

Whilst 1998 and, to a lesser degree, 2010 are still well clear on both the UAH and RSS TLT's, the ongoing el Nino appears to be driving recent TLT's upwards. (My money is on the release of Latent Heat into the atmosphere as a result of increased evaporation from the ocean surface.)

As of October, 2015 is currently 3rd on the UAH y-t-d, and 4th equal for RSS. The recently released RSS figure for November is the highest yet seen for that month, and will therefore break the tie for 4th place once it has been incorporated.

The October TLT figures for RSS showed 2015 in second place, just 0.02 behind 1998. On the other hand, the UAH figures had 2015 as easily the warmest October thus far, being a full two tenths hotter than both 2014 and 2012.

Your claim that the NASA Gistemp LOTI figures are somehow rendered useless doesn't seem to be borne out by the numbers.

"For Cuzco, of course if nobody cares about a change of 1C or more in temperatures..."

Out of curiosity, have you made any enquiry of NOAA as to the apparent discontinuity? I suggest NOAA, rather than NASA, as it is the former organisation that appears to "own" the Global Historic Climate Network. Any time that I have either had a query, or wished to point out a problem, I have found NASA, NOAA and the NSIDC invariably helpful. (In fact, the only such organisation I've had trouble with is the UK Met Office - and that's only about 20 miles away!)

As I understand it, NASA Gistemp derives its land temperature numbers from around 6,300 entities on the GHCN, and the ocean covers about 70% of the planet. Even if there is a genuine problem with the Cuzco data, it represents about 3 orders of magnitude down into the noise level. (Obviously, if there are many such instances, then it becomes a whole new ball game.)

John Christensen

Hi Bill,

Thank you for the response.

I do not believe there is interest in elaborating this topic on this blog, so let me just reply briefly that I agree with you that there seems to be strong correlation between GHCN station data and satellite temperature trends since 1979.

Cato Uticensis

Sorry you have seen insinuations in my post.

They were not insinuations, just statements.

In the Po Valley, also due to the significant reduction of pollution and, therefore, of fog, temperatures in winter have gone up. And you know what? We are happy with that. We can enjoy warmer days in the same places where we were used to languish in pollution, fog, icy temperatures and all the rest of it.

Reduction of pollutants has brought only advantages, unless one wants to believe that "warmer" means "worse" in any case. There is a long way to go, yet, as after many days of high pressure PM10 tend to accumulate and air quality is affected accordingly.

The "local warming" issue has been studied rather extensively I guess and is the subject of several papers. It would be nonsense to ignore that the same meteorological stations which 20 yrs ago were in the middle of the countryside and today are surrounded by asphalt have not been affected by urbanisation.

This does not mean (DISCLAIMER) that local warming is the reason why temperature have been increasing globally. Some scientists have tried to quantify this effect, with quite different conclusions. According to some studies it is negligible, according to others it is quite considerable.

I will make sure that more DISCLAIMERS are incorporated in my posts in the future. So no one gets offended by possible insinuations potentially going against the mainstream.

Regarding the difference between NASA and satellite data I strongly disagree with the statements made about the "strong correlation", especially in the last decade, but I agree it is an off-topic and don't want to add further more disclaimers.


... dream on. this has been clearly dealt with by the IPCC, among others - the urban heat island effect is significant, but 'research has consistently shown that global warming cannot be explained by local changes, including the heat island effect' if memory serves is the line from my PhD thesis. I could give links to the time series temperature graphs and everything but there's really not much point - it's all on the IPCC website

Rob Dekker

John Christensen said


GISS v2 (Used until 2011) Cuzco station temperature history :


John, I am not sure if you posted this claim on purpose, or if you posted it out of ignorance.

NOAA clearly posts 4 stations in Cuzco, Peru, with your stations 309846860000 and 309846860003 being two of them

So you are simply stating two stations out of 4 in Cuzco, and your statement that one is "After 'GISS Homogeneity Adjustment'" of the same station is simply false and misleading.

Not sure why Neven even lets you continue to post your clear biased messages here.


I don't mind the biased messages so much, mine are biased too (but John could be a more transparent about it). Besides, it's the freezing season, so it's not that busy around here (I won't tolerate this during the melting season).

But as Bill said, the global average temperature is going to be smashed this year (which is only logical given the combination of AGW and an El Niño that will come in as one of the 3 strongest measured). It will be interesting to see if this has a (delayed) impact on Arctic temperatures. We've seen what the second warmest July on record did to the ice last melting season.



you did miss my point!

It’s fine that Canadian researchers now are able to melt loads of Arctic sea ice in their model. At the moment, their best attempt brings the 5-year average below 1 mio. Km2 in the early 2030ies. They do this mainly by removing the global sulphate forcing from a series of RCP8.5 runs in their model. If they add some yellow carbon forcing from forest fires (yet to come), I am sure they will hit the bottom of our civilization (< 1 mio. Km2) well within the next decade.


I was not offended and your ideas are not mainstream. Your dream may go down the drain one day. Until then, please enjoy the warmer days in the Po valley – and beware of those fine particles. I believe that the PM2.5s are even worse than the PM10s you refer to.

John Christensen

Sorry Neven, but please let me provide a brief reply to Rob Dekker about ignorance.

- Yes, this city has four temperature stations
- I selected the data set "after combining sources at same location" so yes, my wording above could have been more accurate
- Both the v2 and v3 homogeneity adjustments are made on the combined station data, not individual station data, so my links provided a comparable view
- The v3 homogeneity adjustments have a stronger uptick in the temperatures, which is why I provided that link rather than the v2 homogeneity adjustment link

Check again for yourself, please.

Wayne Kernochan

Hi Neven (et al),

I really should have weighed in earlier -- other matters. James Hansen wrote extensively about the climate-change effects of aerosols in general a few years ago. From memory, this is what he said: increases in aerosols primarily from coal are counteracting (really, slowing) temperature rises due to climate change. However, this is true only as long as aerosol pollution continues to increase. If aerosol pollution levels off, temp rises start to act as if there is no pollution at all. If aerosol pollution decreases, temp rises are faster than the underlying carbon emissions.

As Hansen also noted, there is a limit to how much aerosol pollution people can bear, and therefore at some point in the future people have to start decreasing their aerosol pollution. So all that has happened is that we have been lulled into a false sense that things are better than they are.

A recent article at www.thinkprogress.com/romm/issue details what this means for the Chinese, who are now the primary aerosol polluters. Of particular note is that some of the pollutants can spread halfway around the world, giving Los Angeles an extra day per year of smog.

I would suggest that the Arctic sea ice effects are simply part and parcel of the global effects. Less carbon pollution means more sunlight, heat, and global warming worldwide, not just in the Arctic.

Side notes: According to a recent article in MIT Technology Review, India is caught between a rock and a hard place. To avoid uncontrollable violence, it needs to upgrade living conditions fast in a nation where 9/10 are still at poverty level, and that means coal. They are trying to move to solar as fast as they can, but practically they project increases in coal use for the next 5-10 years at least.

With regard to technologies removing CO2 from the atmosphere, all technical articles I've read agree that deployment of these has been very slow to happen and significant effects of these are not projected for at least 5-10 years, if ever.

Wayne Kernochan

P.S. I just took a look at the November CO2 figures (Mauna Loa). It's an almost unprecedented almost 3 ppm (2.89) increase from Nov. 2014 (the full year of 1998 saw a 2.93 increase, the only comparable full-year figure) -- and afaik that increase has nothing to do with el nino. That's just awful. It's hard not to get sick to my stomach with that one.

Rob Dekker

John Christensen said

- Yes, this city has four temperature stations

You could have mentioned that right off the bat.


That is not clear from your description, nor from your links.
In fact, your links suggest the data is from two DIFFERENT stations, not "combining sources at same location".


is a link to the global difference between v2 and v3.
So even if your Cuzco data is what you say it is, it does not make one iota difference in the global picture. If anything, Peru shows less of an increase in v3 than it does in v2.


See the link above.
Your claims simply do not hold. Neither local, nor global.

John Christensen

My point was merely that there is a large difference between actual station data and homogenized station data, which is interesting, at it is always the homogenized data that is reported out as the actual changes in global temperatures.

To connect the GISS homogenization and this blog entry:

"The GHCN/SCAR data are modified to obtain station data from which our tables, graphs, and maps are constructed: The urban and peri-urban (i.e., other than rural) stations are adjusted so that their long-term trend matches that of the mean of neighboring rural stations. Urban stations without nearby rural stations are dropped."

In principle, this could mean that Cuzco station data is homogenized to fit the surrounding rural stations, and that the homogenization therefore incorporates elimination of aerosol pollution..

Enough said, and realizing that bias is a fundamental part of our cognitive and perceptive systems, we probably need to find a way to live with that.



This is handwaving. Quantify please. And what is your improved homogenization method to reduce this quantified number or percentage?

bias is a fundamental part of our cognitive and perceptive systems

It seems you're making a successful effort at proving this, given that you believe that hundreds/thousands of people and respected organisations are tampering with data to achieve a pre-determined end.

John Christensen

Hi Neven,

Yes, handwaving it was, since Rob brought the comparison between two homogenized data sets, and my argument was the difference between actual station data and homogenized data..

I will be happy to quantify the temperature adjustments between the actual station data (combined station version) and the v2 and v3 homogenizations.

The columns are:
1. Year
2. Actual combined Cuzco station temperatures
3. Adjustment in the GISS v2 homogenization
4. Adjustment in the GISS v3 homogenization

'X' is used where data is not available

Year v2 Station Station/v2 Hom Station/v3 Hom
1937 13,46 X X
1938 13,31 X X
1939 13,38 X X
1940 13,75 X X
1941 14,08 X X
1942 14,71 X X
1943 14,58 X X
1944 14,84 X X
1945 14,55 X X
1946 X X X
1947 X X X
1948 X X X
1949 X X X
1950 X X X
1951 X X X
1952 X X X
1953 X X X
1954 11,85 -0,7 -0,82
1955 11,8 -0,7 -0,8
1956 11,74 -0,7 -0,78
1957 11,92 -0,6 -0,83
1958 12,23 -0,6 -0,8
1959 13,01 -0,6 -1,32
1960 12,57 -0,6 -1,23
1961 12,93 -0,6 -1,41
1962 12,73 -0,5 -1,3
1963 12,6 -0,5 -1,3
1964 12,84 -0,5 -1,22
1965 12,83 -0,5 X
1966 12,99 -0,5 X
1967 12,84 -0,4 X
1968 12,69 -0,4 -1,46
1969 13,61 -0,4 -1,7
1970 13,45 -0,4 -1,72
1971 12,84 -0,4 -1,6
1972 13,14 -0,3 -1,76
1973 13,34 -0,3 -1,75
1974 11,88 -0,3 X
1975 11,48 -0,3 X
1976 11,28 -0,3 -0,31
1977 11,53 -0,2 0,01
1978 11,48 -0,2 0,04
1979 11,63 -0,2 0,02
1980 11,69 -0,2 0,08
1981 10,98 -0,1 0,2
1982 11,49 -0,1 X
1983 12,66 -0,1 -0,32
1984 11,73 -0,1 -0,17
1985 11,65 -0,1 -0,13
1986 11,46 0 0,17
1987 12,49 0 0,02
1988 12,26 0,01 -0,03
1989 11,38 0 -0,01
1990 12,03 0 -0,12
1991 X X X
1992 X X X
1993 X X X
1994 12,2 0 -0,19
1995 13,13 0 -0,67
1996 12,17 0 -0,45
1997 X X X
1998 X X X
1999 X X X
2000 X X X
2001 X X X
2002 11,73 -0,01 -0,04
2003 11,98 -0,01 0,12
2004 11,73 -0,01 0,11
2005 12,18 0 0,1
2006 X X X
2007 12 0 0,1
2008 11,88 0 0
2009 12,2 0,01 -0,05
2010 12,68 0 0
2011 12,18 0 0,06

1. The warmest period in actual station data is 1937-1945, but these years have been removed in both versions of homogenized temperatures.
2. v2 homogenization seems to provide a crude downward adjustment, which is increased as you move back in time.
3. v3 homogenization is typically more significant in the years prior to 2000 with a max downward adjustment of 1,76C in 1972.
4. Recent years have seen very little or no adjustment in the homogenized versions.


John Christensen,

It seems rather clear for me, that you do not really know, what homogenization, raw data, or measurement means. Please take it not personally, most people do not know the details.

We have certainly not to live with the biases, homogenizations are made, to REMOVE THE BIASES.

Everytime you make measurements these are full of biases. There are methodological biases, instrumental biases, personal biases etc.
Everytime you make a measurement, you have to verify it. IN geochemistry we use standarts to do this sort of homogenisation. Every 10th measurement we do with any instrument is done for calibrating this instrument. If you ever have made measurements in chemistry or physics, you should know, that there are plenty of mistakes to do. It is not only to read a thermometer and write the measurement down.
When later your standart appears not to be calibrated right, you have to rehomogenize all of your raw data again, the same, when you find earlier unknown biases.

Imagine several 1000 stations, all with their own biases, changing over time, with instrument changes, operator changes etc, then you understand the importance of homogenisation, or in other words, veification of the raw data and correction of the raw data. Then you know, why raw data is not reported, because the raw data is utterly useless without homogenisation, for every measurement done.

If you do not have the possibility to verify the raw date and correct it, then you have to remove the data, you can not use it.

NASA and the other organisations are completely open with their way of homogenization, why it is done and how it is done. You find it when you dig in their homepage, and you find it, when you simply ask.

If you really think, that we probably have to live with biases, then you must distinguish between your own perceptual biases, and instrumental etc. in the data. With the first you may live, with the later you are able to remove them through homogenization.

Folke Kelm


I think this is the best possible answer to end this discussion (that has been discussed about a zillion times elsewhere).

Rob Dekker

In the context of the recent revelations about what the large oil companies, and specifically Exxon, knew about CO2 and the relation to climate change, way back in the 70's, Mr. Revkin of the NYT of all people states :

I suggest that Exxon, and perhaps the fossil fuel industry more generally, might help propel a vigorous new burst of research in ways to take back the CO2 added to the atmosphere by fossil fuel combustion at a scale that would matter to the climate system.

Now that is what I call a bold statement..

Rob Dekker

Link here


What a great idea! Let's wait another 40 years and see what happens.

Bill Fothergill

Nice link Rob,

As I was reading, a thought sequence insinuated itself into the old grey matter. It was along the lines of...

tobacco industry ... Fred Seitz ... George C Marshall Institute ...

@ Neven ... 40 years? ... possibly too optimistic perhaps

Wayne Kernochan

Andrew Revkin is known for this kind of "your representations of scientific climate-change knowledge are exaggerations because I have my pet scientists" and "let's do something else instead" reporting -- if reporting isn't too kind a word. The Times had a superb climate-science reporter in Justin Gillis but took him off the beat except for occasional blog posts. Notice the bit about "why should they bother to keep fossil fuels in the ground" and the total disregard of folks like Ken Caldeira who have actually looked at these potential technologies.


Andy Revkin, well trained as a journalist, tells 2 sides of the story. One side is supported by 97% of the published climate scientists. The other side is the 3% who. for a variety of reasons, see things differently. He gives them equal weight in his "objective" reporting. Brilliant. I love objective journalism.

D above reminds me of the Pee Dee belemnite, a standard used in isotope geochemistry. The Pee Dee River, where this fossil is abundant flows into the Atlantic in South Carolina.

Merry Christmas from the Carolinas where temps were in the 80's today and dewpoints in the 70's. High temps in Celsius were 25 to 29 degrees. It can be warm this time of year but this late summer like weather was ridiculous.


Rob Dekker

Revkin quotes Myles Allen to support his argument (that fossil fuel companies should invest in "take-it-back" methods), which is unfortunate, since Myles Allen's train of thought is the other way around :

Allen argues (at AGU'14) that a carbon tax by itself will not lower CO2 emissions. After all, we already pay a "carbon tax" in the price of gasoline at the pump. More expensive gasoline (due to a carbon tax) will not get people out of their SUVs, and thus will have maginal effect in lowering CO2 emissions, Allen argues. And I think he has a point there.

Allen suggests that a "carbon tax" is not enough, and there should be a climate policy in place where fossil fuel companies are required to sequester CO2 by a particular percentage of fossil fuel extracted. Something like 1% this year increasing by 2% each year, so that after 50 year, 100% of fossil carbon extracted will be sequestered. If a company does not reach its imposed sequestering percentage, then it will be heavily fined (by the ton CO2 not sequestered).

Allen's point is that that is the only thing that governments can MANDATE, AND it WILL be effective in controlling climate change.

Also, it it will put the cost (of sequestering) on the companies that extract fossil fuel. Which then in turn will spur that research into sequestering (and "taking-back") that Revkin is taking about.

The problem with Allen's effective plans is of course is that so far NO government has imposed ANY sequestration mandates on its fossil fuel extraction companies.

Rob Dekker

Of course, this makes the issue of CO2 one of political will.

Because Revkin does not even mention the possibility that fossil fuel extraction companies could by themselves start a serious sequestration program.

John Christensen

Hi D/Folke,

Thank you for your note, but yes; I am aware of the need for homogenization of the station data, as there are many factors that will cause bias in the temperature readings (Construction of station, placement, wind, etc.).

For Cuzco in 1972 they had three stations with these annual averages (Which therefore also is not raw data): 11.99, 13.77 and 13.68. Readings from the two last stations are very consistent over the 60s and the 70s, while temperatures went down on the first station in the years prior to 1972.
The average of the three stations (v2) as mentioned earlier is 13.14.

However, in GHCN v3, the combined annual average temperature for the stations in Cuzco is presented as 11.48.
Finally, with the homogenization (v3) it becomes 11.38.

The homogenization is used to align local station averages with the trend obtained from local/regional climate trend analysis. However, in the case of Cuzco, nearby stations are few, have relatively short temperature history and some are located in the tropical climate zone, which is quite dissimilar to the alpine climate surrounding Cuzco.

I will check with GISS if they can share more details, e.g. on the regional climate trend data and agree that there is no need to continue the discussion on this blog.

Happy New Year everyone!

Bill Fothergill

" ... reminds me of the Pee Dee belemnite, a standard used in isotope geochemistry ..."

Or, as Midge Ure might have put it ... "Ah, Vienna"



I would like to completely disagree about the possible effectiveness of a carbon tax.

When gasoline hit $5.00 / gallon in California a few years ago, bus ridership skyrocketed, especially during the commute hours. Where two busses per hour were all that were needed to pick up everyone on my route before that (and they were only 50% full), they were able to run 6 SRO busses per hour for over a month (until gas prices fell again).

I have no doubt that $10.00 / gallon would further increase the use of public transit.

And while people may not trade in their SUVs immediately, they tend not to replace them when gas prices are high.


Rob Dekker

Bfraser, you misunderstood.
Carbon tax is one policy instrument to lower emissions, but mandated sequestration is another one.
The point that Myles Allen is making is that the two are independent, and that mandated sequestration is guaranteed effective.
In the end, we may need both of these policies to keep warming of our planet below 2C.

Rob Dekker

To see ho little influence price has on consumption : Doubling of oil prices in 2008 barely made a dent in oil consumption world-wide or the US :
and most of that dent was caused by a world-wide recession.

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