‘Bias & Failure’ Exposed in Hyped New Alarmist Climate Paper
Jan Zeman provides a telling appraisal applying official raw data of global surface temperatures to refute alarmist claims made in a recently trumpeted paper by Cowtan and Way. Authors’ claims of increased warming are controverted by compelling empirical evidence suggesting an emergent cooling trend instead.
Zeman’s analysis shows Cowtan and Way may have intentionally inserted a warming bias to fill a gap in data coverage of the tropical and polar regions. Principia Scientific International has pleasure in publishing Zeman’s damning full report below:
SIGNS OF COOLING
by Jan Zeman
Because there was a lot of publicity around the Cowtan and Way 2013 paper I decided to look into the issue, although, I note, it is not main concern of this article and it only makes suitable pretext to examine what is really going on with the global temperatures recently.
I was not much interested in their calculations and methods (since I’m not much interested in methods of data torture. Besides, they have already been scrutinized by much more knowledgeable people), but rather in the following questions:
Where did they obtain such data that would support a “two and a half times greater” rise of global temperature anomaly “trends starting in 1997 or 1998” in their “hybrid global reconstruction” when compared to the HadCRUT4 global temperature anomaly data-set, what such data really show and whether such data agree with other data or not?
The main rationale of their analysis seems to me to be that there is some missing coverage for the HadCRUT4 global temperature anomaly dataset “with the unsampled regions being concentrated at the poles and over Africa” and that it is the alleged reason why the HadCRUT4 dataset outcomes are purportedly biased, allegedly showing less warming than there is in reality. The main result of their analysis widely publicized was the bold red global trend. Because of this, the first thing I looked for was whether there actually are other data covering the regions and what trends one can find there.
Tropics
For starters, let’s see a comparison of HadCRUT4 and satellite lower troposphere data for the tropics.
(Note that I chose trend period exactly October-October to avoid potential disputes about the seasonal variations and cherry-picking. The data and calculations are available here.)
What we immediately see on the graph is that the HadCRUT4 trend 1997-present for the tropics (30S-30N) is flat (but it is slightly rising for the whole globe ~0.046°C per decade). We also see that both the UAH (the dataset Cowtan and Way likely used for their “reanalysis“ of the HadCRUT4 dataset) and the RSS satellite records show a descending temperature trend in the 1997-present period for the tropics. The only satellite data which show a rising temperature trend in the tropics is the UAH lower troposphere-land.
But since the UAH dataset shows a descending trend for the tropics when the oceans (covering ~70{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} of the tropical region) are included, it is clear that the satellite data-sets including the UAH for the tropics as a whole clearly do not show warming in the tropics for the period. So they can hardly contribute in a consistent way to change the flat HadCRUT4 tropics trend into a rising trend for the period.
We can therefore immediately conclude that if Cowtan and Way used the UAH tropics-land data-set to anyway do so, it would be absolutely inconsistent, directly contradicted not only by another satellite data-set (RSS), but by the UAH satellite dataset itself – which doesn’t show warming in the tropics as a whole for the period in question, on the contrary, it shows visibly a cooling trend for the tropics. So to take only the land data showing the warming from the UAH data-set, mess up the official data-set (showing a flat trend for tropics and warming presumably somewhere else) with them, allegedly correcting its alleged bias, it would be clearly a sign of a bias on their side, to put it extremely mildly.
In any case, a hypothesis that the UAH satellite datasets can somehow change the HadCRUT4 trend in the tropics into a rising one for the period 1997-present is therefore not only contradicted by the RSS satellite record, but it is directly falsified by the UAH lower troposphere temperature anomaly dataset for tropics itself, because it clearly shows a descending lower troposphere temperature trend there, while the HadCrut4 shows a flat trend there – to imply a rising trend in data showing flat trend for whole region with data showing descending trend for the whole region quite defies basics of logic.
The divergence
Recently in the article written by Steven McIntyre, he showed that the Cowtan and Way hybrid global data start to markedly, one could say “hockeystickly”, diverge from the HadCRUT4 global data in about 2005. He showed it well on this his picture:
The graph shows that it is in about 2005, where the Cowtan and Way data start to show a quite consistent divergence from the HadCRUT4 data – before 2005 they show a negative trend and then quite suddenly a positive one (and if we look into the Cowtan and Way article now available for reading, we find out that their figure 5b shows there a divergence already at least from 2003). It is good to note here that one of the two authors even participated in the discussion below McIntyre’s article at the Climate Audit, but he didn’t object to the graph. A similar break-point for both Cowtan and Way data-sets is shown by Bob Tisdale here, and he notes what it has likely to do with the polar amplification.
It is clear from the graph that the divergence is most likely the chief source of the rising trend in their global hybrid data-set purporting to tackle the bias in the HadCrut4.
There was another article written about the possible cause of this divergence in their datasets that they paradoxically throw up valid surface records, especially around Antarctica, in Africa and the Arctic in the 2005-present period. But it was described there, so I will not repeat once written. And since the tropics do not show a warming trend (and I note that in the period since 2005 the HadCRUT4 data-set shows for the tropics 30S-30N the relatively impressive downward trend of -0.134°C per decade – which is hard to beat with infilling poor coverage with invented values in the polar regions – simply because the 30S-30N is exactly half of the Earth surface area, while both polar regions combined less than 10{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117}!), let’s have look at the other regions where they claim low coverage causes a bias in the HadCRUT4 – the polar regions – and see what really is going on there in the period of the divergence. Because it has possibly broader implications than just falsifying the Cowtan and Way 2013 results, especially the red trendline.
Polar Regions
Let’s first see what’s shown by the lower troposphere satellite data for the polar regions:
(used data and calculations available here)
What we see on the graph is that since 1997 there has been a rising trend both in the Arctic (steeper) and Antarctica (less steep). However this trend clearly stopped in the Arctic before 2005 in both the satellite datasets, while it continued to rise in the UAH dataset for Antarctica.
Let’s see why:
Again, as in the tropics, the land record in the UAH data-set shows a much steeper slope than the ocean record – which shows an almost flat trend in the UAH.
It very much seems that the UAH dataset for the Antarctic land is contradicted by the RSS dataset.
Are there other data-sets which would support the rising trend in UAH data since 2005?
Quite the contrary – there are others which contradict it.
First, there are the data from the Antarctic surface stations. I took the data from GHCN for them, made a sample of 20 surface stations (all Antarctica surface stations available at GHCN which are not missing more than one year of data since 1997 and have data to present) and I have plotted their temperature mean with trends:
(used data and calculations available here)
From the above graph it is quite clear that, although there is a rising temperature trend since the 1997, there is no rising temperature trend after 2005, as measured at the surface stations in the Antarctica. The majority of them show a descending trend for the period, especially those further inland (2005-12 trend slopes for Amundsen-Scott: -1.56°C, Byrd station: -1.25, Vostok: -1.08°C).
So is there actually a warming trend in the polar regions since 2005?
As I have shown, most likely not in the Arctic. No data-set we have looked at shows there a warming trend since 2005.
But is there warming in the Antarctica? The UAH data-set (although contradicted by the majority of the Antarctic surface stations, especially those inland, and by the RSS data-set) shows warming both for land and ocean there.
Can we further contradict the UAH data-set, not just for the land, but the ocean too? I think we can very well.
Sea ice
There is actually a data-set, which covers the polar and sub-polar regions very well. It is not a temperature data-set, but it has a lot to do with temperature. It is the NSIDC sea ice index data-set and it covers the polar regions with daily cadence, extremely rarely missing coverage and with no major issues (at least since 1988 – in 1987 there is a discontinuity) – because sea-ice is, unlike surface temperature, actually possible to measure accurately with satellite instruments. So let’s have look at what it shows:
(data with calculations are available here)
We can immediately see on the graph that the monthly global sea-ice extent recently reached the highest level since 1999 – which oddly went unnoticed by our climate watchdogs. Also the southern sea-ice extent – in the region which is allegedly warming according to the UAH and Cowtan with Way – reached not only a higher level than in 2005, higher than in 1997, but it very recently again reached likely the all time high in the history of the satellite sea-ice extent measurements since 1978. (As I look into the NSIDC daily sea ice data – available here, and I do a small extrapolation (if Cowtan and Way can why not me just for fun) over the one remaining month, it also looks very likely to me that this whole year’s sea-ice averages will be the highest since 2003, and very possibly even since 1999 – if you don’t believe just look carefully at this graph from UIUC.)
Note also the trends in the above graph (which have periods exactly global minimum-to-minimum and maximum to maximum using the resolution of the daily data from 2005 global minima and maxima to 2013 minima and maxima) – both are rising.
But it is not the temperature which is rising there, it is the sea-ice extent. And it really doesn’t look consistent with the Cowtan and Way global warming trend supposedly due to alleged warming in the polar regions.
A warming usually doesn’t freeze water on hundreds of thousands square kilometer areas.
Thanks to NSIDC, we can also compare the maps for both hemispheres’ yearly maxima. Here it is for Arctic. Note the numbers.
We see that the yearly sea ice maxima were higher for Arctic in 2013 than in 2005, which further confirms both the RSS and UAH satellite data for the lower troposphere temperature anomaly in the Arctic. But it should definitely be mentioned that the Arctic sea-ice still shows a descending trend in the period 2005- present. Nevertheless, this trend has over two times less steep slope than the rising trend in Antarctica for the sea-ice extent and half less steep slope for the sea-ice area. So there is an observed net gain in the global sea-ice trends of about 1.5 million square kilometers per decade for the sea-ice extent and about 1 million square kilometers per decade for the global sea-ice area.
I would very much think that if we speak about global temperatures and their trends, we must also consider global, not just hemispherical, trends which indicate them. Especially for oceanic phenomena such as sea-ice, because there is very uneven distribution of the ocean over the globe and the Arctic sea ice is also, unlike that around Antarctica, quite tightly constrained by the surrounding land and subjected to currents from the lower latitudes of the Atlantic, while the Antarctica sea ice is constrained by land from the other side, so it grows into open ocean at lower latitudes than in Arctic. So the two dont allow an easy mutual comparison.
Here is the comparison for Antarctica:
(Source here)
Even though we can question whether the rising global sea ice trends have statistical significance, there quite clearly is no descending global sea ice trend since at least 2005 (where the Cowtan and Way data start to diverge from the HadCRUT4 but in the other direction than the seaiice record implies). On the other hand, one finds such a descending (or at least flat) trend in (nearly) all official data-sets for the global temperature anomaly – including the UAH global data-set for the lower troposphere – the trend looks to me perfectly flat, but actually it shows a rising trend: +0.09°C together with HadSST2 and HadSST3 which show even +0.3°C …per thousand years.
How long has warming been absent?
After we have found there are records that contradict the claims of Cowtan and Way, we can also ask: from when does the sea-ice trend go flat? This can serve us as an indication from when, at least (if we omit lags in the ocean), the global temperature anomaly trend is also likely flat. Let’s answer this question with the last graph making our final point:
(Note that the running average curve ends half a year before present, so it doesn’t show what will most likely happen with it in the future – due to record highs this October-November it will very likely surpass the 2000 level.)
Now everything starts to make sense: Most of the global temperature anomaly records are flat or descending since ~2000-1, and the multiple global surface temperature anomaly datasets (GISTEMP, HADCRUT3, HADCRUT4, WFT, HADSST2, HADSST3) compiled from the surface measurements quite very strikingly agree with each other in this – unlike the two satellite datasets for lower troposphere (UAH and RSS) which disagree somehwat with each other, one showing a flat trend since 1997, the other a rising one. But I would like to note here this article is not a critique of the satellite datasets. Each uses different methods, so it is only natural their results differ, and also, they don’t measure surface temperature anomaly and it is quite problematic to use them even as proxy for it, especially at high latitudes, where is substantially different seasonal insolation profile than in the rest of the world.
In the last graph we also see that the sea-ice extent trend is flat or rising since ~2000-1. (Note the graph is using daily NSIDC sea ice extent data, but similar results are also shown in the monthly data for both sea ice extent and area)
The above-named global surface temperature anomaly datasets together can hardly be challenged by the Cowtan and Way data torture; cherry-picking suitable parts from the UAH dataset to confirm their bias, quite clearly inconsistently misinterpreting the dataset and treating the values as if they were a surface record itself. Thereupon, implanting just the suitable selected trends from it into the Hadcrut4 dataset, (which in the original version is more or less consistent with the other surface datasets), then putting the proverbial apples into boxes with oranges, creating a surface record in the HadCrut4 gridcells of ‘surface measurements’ quite literally plucked out of thin air.
Altogether, what I’ve shown indicates very well that since ~2000-1 there has been no rising surface temperature anomaly trend. There is only one dataset which disagrees with this conclusion and it is the UAH lower troposphere temperature anomaly dataset, especially due to its rising trend in Antarctica. Note that here I’ve made the only emphasis in this article for the reader to notice the difference from the “surface temperature anomaly”. It has good reason – it is exactly in the polar regions, where the very high incidence angle of the incoming solar irradiation causes the bulk of the solar irradiation to be absorbed in the atmosphere which is heated more than the surface, which, covered by snow and ice, reflects most of the insolation back and instead of warming itself adding even more to the warming of the lower troposphere. Moreover, loads of heat created by the oceans’ absorption of the solar irradiance at the lower latitudes is transported into the polar regions by oceanic currents, and are dissipated into the atmosphere and eventually into space there – especially on the Atlantic side of the Arctic.
Closing remarks
It very much seems that the trend break-point in the Cowtan and Way data is itself a result of a bias; a miserable failure, likely when trying to account for the positive polar amplification. The problem is there exists, for most of the time, a neutral (or even negative!) amplification phase.
On the evidence, it very much looks like there is no reason to believe there is a warming trend in the global surface temperatures, at least since 2005 and quite likely even since ~2000-1. Perhaps even much less because of a bias in the global surface temperature anomalies due to the allegedly insufficient coverage in the tropical and polar regions.
In fact the global sea-ice data, supported by multiple other data-sets, give quite very compelling evidence to the contrary.
And data is what counts in science. The scientific method is based on falsification, not confirmation bias. If the data doesn’t agree with a hypothesis, then in the overwhelming majority of cases it is the hypothesis which is falsified, not the data.
In this case, the extensive real data falsifies a hypothesis literally based on no data (but where ‘data’ is invented from thin air to make such an hypothesis possible). Moreover, this hypothesis was clearly postulated to significantly change the outcome of the real official data-set (whatever we may think about the Hadley Center, CRU and MetOffice, at least it is based on real measurements and still with a relatively conservative approach without infills when compared to other global data-sets as NCDC or GISTEMP LOTI*). In addition, we may infer there is clear intent here to put in doubt the current, flat (if not cooling) global surface temperature anomaly trend, perhaps for more political than scientific reasons.
Bob Tisdale shows from another dataset (see the footnote) that the southern oceans are cooling and there is virtually nothing else than ocean there between Antarctica and 60S. This evidence looks to be confirmed by the rising sea-ice extent there. And while the tropics also cool at quite an impressive rate and we see no rising temperature trend in the Arctic from the two satellite datasets – will we really believe there is a warming trend? If perhaps it is warming somewhere (maybe in Antarctica or elsewhere) where measurements haven’t yet been taken, is it somehow possible those unmeasured regions will change what is most likely an overall flat or descending global surface temperature anomaly trend into a warming one? Probably not. But such is the global warming overheated dream manufactured in Cowtan and Way’s computers.
This apparently desperate effort to manufacture a global warming trend using the HadCRUT4 dataset and cherry-picked satellite data seems to be not only about serving a man-made global warming agenda but also a clumsy effort to hide a compelling sign of planetary cooling.
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* If one wants to brush up on how it relates to the sea-ice I recommend the final note from Bob Tisdale’s article here, which, to make this bit shorter, I allow myself to point out just one sentence from: “GISS masks (effectively deletes) sea surface temperature data anywhere sea ice has existed.“
Also note that he also shows a consistent temperature decline for the Southern Ocean SST from yet other data-set (Reynolds Ol.v2) – see his graph here – from here.
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