Tuesday, 10 February 2015

Climatologists have manipulated data to REDUCE global warming

Climatologists are continually accused of fiddling with the data to make global warming stronger for political purposes by political activists.

A typical scam is to show a few stations that have been adjusted upwards and act as if that is typical. For example, recently The Telegraph article, "The fiddling with temperature data is the biggest science scandal ever", wrote about someone comparing
temperature graphs for three weather stations in Paraguay against the temperatures that had originally been recorded. In each instance, the actual trend of 60 years of data had been dramatically reversed, so that a cooling trend was changed to one that showed a marked warming.
Three, I repeat: 3 stations. For comparison, global temperature collections contain thousands of stations. CRUTEM contains 4,842 quality stations and Berkeley Earth collected 39,000 unique stations. No wonder some are strongly adjusted up, just as some happen to be strongly adjusted down. In fact it would be easy to present a station where the raw data shows a decreasing trend of several degrees being adjusted upwards, but then the reader might start to think if the raw data is really better.

What these people do not tell their readers is that the average trend over all station is only adjusted upwards slightly. That would put things too much in perspective. What these people do not tell their readers is why these adjustments are made. That might make some think that it may make sense. What these people normally do not tell their readers is how these adjustments are made. That would not sound sufficiently arbitrary and conspirational.

Last year we had similar scams about two stations in Australia and the stations in New Zealand.

In an internet poll, 88% of the readers of the abysmal Telegraph piece agree with the question: "Has global warming been exaggerated by scientists?"

I hope that after reading this post, these 88% will agree that they have been conned by The Telegraph. That scientists have actually made global warming smaller.

Zeke Hausfather, an independent researcher that is working with Berkeley Earth, made a beautiful series of plots to show the size of the adjustments.

The first plot is for the land surface temperature from climate stations. The data is from the Global Historical Climate Dataset (GHCNv3) of NOAA (USA). Their method to remove non-climatic effects (homogenization) is well validated and recommended by the homogenization community.

They adjust the trend upwards. In the raw data the trend is 0.6°C per century since 1880 while after removal of non-climatic effects it becomes 0.8°C per century. See below. But it is far from changing a cooling trend into strong warming.

(In case you believe many national weather services are also in the conspiracy: a small part of the GHCNv3 raw data was already homogenized before they received it.)

Not many people know, however, that the sea surface temperature trend is adjusted downward. That does not fit the narrative of WUWT & Co. It sounds like even many scientists did not know that. These downward adjustments happen to be about the same size, but go into the other direction. See below the sea surface temperature of the Hadley Centre (HadSST3) of the UK MetOffice.

Being land creatures people do not always realise how big the ocean is. Thus if you combine these two temperature signals taking the area of the land and the ocean into account you get the result below. The net effect of the adjustments is a reduction of global warming.

It is pure coincidence that this happens, the reasons for the adjustments are fully different.

The land surface temperature trend has to be adjusted up because old temperatures were often too high due to insufficient protection against warming by the sun and possibly because the siting of the stations improved. There are likely more reasons.

The sea surface temperature are adjusted downward because old measurements were made by taking a bucket of water out of the ocean and the water cooled by evaporation during the temperature measurement. Furthermore, modern measurements are made at the water inlet of the engine and the hull of the ship warms the water a little before it is measured.

But while it is a pure coincidence and while other datasets may show somewhat different numbers (the BEST adjustments are smaller), the downward adjustment does clearly show that climatologists do not have an agenda to exaggerate global warming. Like all reasonable people already knew. That would still be true if the adjustments had happened to go upward.


Small networks

The smaller the networks, the larger the size of the non-climatic changes typically is.

A recent paper about the US mountain network (SNOWTEL) explained that their mountain stations showed more warming than the lower lying USHCN stations. This could be a snow-albedo feedback (that the warming reduces the white snow and reveals the dark surface leading to more warming. However they found it was a non-climatic change in the temperature due to in the installation of new equipment. The new instruments recorded about 1.5°C higher minimum temperatures; an extraordinary large change (the maximum temperature was hardly affected). Accurate data is not just important for trends, but also for physics (snow-albedo feedback).

That is another case of climatologists reducing warming and a feedback.

But what did a well-know blog of the mitigation sceptics, WUWT, write? They headlined: "Another bias in temperature measurements discovered" and opened: "From the “temperature bias only goes one way department”".

The second comment is by "cg": "Lying in Weather Reporting is common place and shamelessly just like the Global Financiers want it. Pure Evil."
Brute: "You sound insane."
KaiserDerden: "no more insane than you do claiming CO2 controls the weather/climate… actually less so in fact ...
Brute: "I have never said a single word regarding how “CO2 controls the weather/climate”. It is curious how much paranoia one finds around here... just about as much as one finds among the warmist cults...."
Sun Spot: "@Brute, you sound sanctimonious"
Ofay Cat: "CG ... you have it right ... those others are uninformed or misinformed. Which means Liberal."
cg: "Thanks"

Let's end on a depressive note. Rob Honeycutt says:
Take note. Proving the conspiracy wrong is sure to be taken as proof you’re part of the conspiracy.

It would be interesting to track, but I somehow doubt the number of “skeptic” posts with accusations of fraud is going to change. And I think this is merely because the source of the “skepticism” isn’t rooted in true scientific skepticism. It’s formed on an ideological basis. So, asking them to accept the data as correct is the same, from their standpoint, as asking them to change their ideology.
End of rant. Sorry for the tone. One sometimes gets the impression that WUWT & Co. select the most stupid memes possible to produce the largest antagonistic effect possible. It would be too easy to talk about the real caveats, the ones also mentioned by the enemy in the IPCC reports. For example, that assessing the impacts of climate change is enormously difficult because it involves ecosystems and humans. For example, that estimating trends in extreme weather is very challenging and very much current research; also partially due to non-climatic changes in the daily data.

[UPDATE. This version got a bit snarkier than usual, which maybe warranted in talking to hardcore mitigation sceptics. To link to in discussions with people who might be open for debate, I have written a second matter-of-fact version: Just the facts, homogenization adjustments reduce global warming. In case of doubt, when you do not know people well, that is probably also the best version.]

Related reading

If you need a peer reviewed reference, the influence of the adjustments on the global mean temperature is also shown in Karl et al. (2015).

Phil Plait at Bad Astronomy comment on the Telegraph piece: No, Adjusting Temperature Measurements Is Not a Scandal

John Timmer at Ars Technica is also fed up with being served the same story about some upward adjusted stations every year: Temperature data is not “the biggest scientific scandal ever” Do we have to go through this every year?

The astronomer behind And Then There's Physics writes why the removal of non-climatic effects makes sense. In the comments he talks about adjustments made to astronomical data. Probably every numerical observational discipline of science performs data processing to improve the accuracy of their analysis.

Steven Mosher, a climate "sceptic" who has studied the temperature record in detail and is no longer sceptical about that reminds of all the adjustments demanded by the "sceptics".

Nick Stokes, an Australian scientist, has a beautiful post that explains the small adjustments to the land surface temperature in more detail.

My two most recent posts were about some reasons for temperature trend biases: Temperature bias from the village heat island and Changes in screen design leading to temperature trend biases

You may also be interested in the posts on how homogenization methods work (Statistical homogenisation for dummies) and how they are validated (New article: Benchmarking homogenisation algorithms for monthly data)


Zeke said...

I'm not sure Nick is a "former skeptic" in any sense. Also, the headline is a tad over the top compared to the rest of the post.

Victor Venema said...

Okay, I may well have been wrong on Nick Stokes. Will correct that link.

The headline is over the top. I am so fed up with this stuff. But it is not too long ago that Tim Ball, a regular poster on WUWT, the mainstream blog of the mitigation sceptics, cited Adolf Hitler to compare climate science with the Jewish world conspiracy.

EliRabett said...

That was way off on Nick Victor. Zeke is right.

izen said...

@-Victor Venema
"The headline is over the top. ..."

Not by much.
I was recently exposed to a video of Lord Monckton lecturing about the 'dark forces' and UN agenda to get rid of governments that would not accept a treaty in Paris, which is why Tony Abbott the Australian leader is under attack, and every freedom loving citizen should support him etc...

Here is a buried link for those that want to sample the rhetoric employed.


Victor Venema said...

Yes, there is probably not a day on WUWT & Co. (that is on the blogs of the mitigation sceptics) that someone does not claim that climate scientists aim to create a dictatorial one-world UN government (I just visited WND, OMG). Either communistic or Nazi.

Still, it was intended as tongue in cheek as the exotic construction "Nazi-communist" was supposed to give away.

In June last year there was a "nice" WUWT post about William M. Connolley, with me as collateral damage. In the post and comments you can find the terms: Creature, sub-human, "the WC needed cleaning", "WC flushed", odious toads, evil, Hitler, Stalin and diseased narcissism. Those are the words of extremists, I would not want to get my science information from.

Victor Venema said...

We will not have to wait long for the next "climate science is a fraud because I have found some stations that are adjusted upward" post. Still, let me listen to Zeke and remove the provocative words from the title so that they do not distract from the information.

Mark Ryan said...

I think this post is simple, clear and very valuable, Victor.

I would think that, given Booker's track record, most of the people who read his columns are already convinced -hence the 88% figure. You are not directly in any kind of 'dialogue' with the uneducable handful, but posts like this provide useful resources for the rest of us.

Brandon R. Gates said...


I am pleased that you followed up on this with a full blog post explaining the sources and methods behind these plots. Thanks also to Zeke for putting them together in the first place. By way of increasing my own knowledge and confidence I was able to replicate the results for HADSST3. For the land adjustment comparison I went after only the stations used to build CRUTEMP and achieved similar results. My final global plot is also quite similar. This makes me happy.

I didn't think the original title of your post was over the top by any means, however I do like that you've changed it.

Marco said...

The comments on Phil Plait's article are not for the faint at heart. When reading those I had to stop myself from loudly screaming "we're doomed!". The stupidity, conspiracy mongering, outright lies, distortions, etc. etc. is just mind boggling.

Anonymous said...

I appreciate the post, however, you spilled an awful lot of ink complaining about conspiracy theorists rather than simply taking a stab at explaining the specific adjustments in temperature records made by the new NCDC algorithm for the 19 station in question. Are you suggesting Paul Homewood is a crank?

Anonymous said...

Not just 3 stations, but 23. He found that data from nineteen were falsified to show global warming instead of actual global cooling. Four of the stations were not altered in either direction. He states:

"But can we trust their figures? We saw previously how the temperature history for Paraguay, and a large slice of the surrounding region, had been altered as a result of temperature adjustments, which had significantly reduced historic temperatures and changed a cooling trend into a warming one.

I can now confirm that similar “cooling the past” adjustments have been carried out in the Arctic region, and that the scale and geographic range of these is breathtaking. Nearly every current station from Greenland, in the west, to the heart of Siberia (87E), in the east, has been altered in this way. The effect has been to remove a large part of the 1940’s spike, and as consequence removed much of the drop in temperatures during the subsequent cold decades."

It seems impossible that a random selection of stations would show only global warming falsifications.

Did he cherry pick these stations, and deliberately omit stations which were altered in the other direction? Is there an equal number of stations that have been altered in the other direction, and are graphs of those before and after readings available? Or did he simply falsify his own report about the altered data?

citizenschallenge said...

Interesting post, though I agree a little more 'meat' would make it better.

Thanks for that reading list, I've gone and shared it.

Victor Venema said...

Anonymous, good question. The way I understand it, the showed that 3 stations had been adjusted from cooling to warming. The other stations were suggested to be similar cases by telling that they also were adjusted upwards, but if you think about that that does not tell you much about the original trend. Knowing the stories of mitigation sceptics, I would thus expect that these other stations mainly had warming trends in the raw data, just a less than after the removal of non-climatic effects.

The smaller the region, the larger the adjustments affect the trends. Within one country or within one network, the non-climatic changes are often similar. Like in the USA where Stevenson screens were replaced by MMTS and ASOS. This is responsible for a reduction in the raw temperatures in the USA of about 0.2°C.

Another clear example of a small network with large non-climatic changes is the mountain network in Western US; see abstract below. The raw data had a non-climatic upward change. After homogenization with the same algorithm used for GHCNv3, the PHA, these trends were reduced by of about 1°C. The trend was made smaller. Rather that acknowledging that climatologists also reduce trends when needed Anthony Watts wrote that this was another indication of a warming bias.

Artificial amplification of warming trends across the mountains of the western United States
Observations from the main mountain climate station network in the western United States (U.S.) suggest that higher elevations are warming faster than lower elevations. This has led to the assumption that elevation-dependent warming is prevalent throughout the region with impacts to water resources and ecosystem services. Here we critically evaluate this network's temperature observations and show that extreme warming observed at higher elevations is the result of systematic artifacts and not climatic conditions. With artifacts removed, the network's 1991–2012 minimum temperature trend decreases from +1.16°C decade−1 to +0.106°C decade−1 and is statistically indistinguishable from lower elevation trends. Moreover, longer-term widely used gridded climate products propagate the spurious temperature trend, thereby amplifying 1981–2012 western U.S. elevation-dependent warming by +217 to +562%. In the context of a warming climate, this artificial amplification of mountain climate trends has likely compromised our ability to accurately attribute climate change impacts across the mountainous western U.S.

Victor Venema said...

citizenschallenge, what is the meat you are thinking of?

Zeke said...


Homewood just cherry-picked a few stations and ignored all the ones that adjustments cool. In fact, the net effect of adjustments is to actually cool the arctic. You might enjoy Dr. Kevin Cowtan's new video, where he shows how to look for yourself (and provides some analysis of the arctic adjustments).


Nick Stokes created histograms of the trend effect of all the adjustments worldwide which might be of interest: http://moyhu.blogspot.com.au/2012/02/study-of-ghcn-v3-homogeneity.html

Victor Venema said...

Anonymous said: I appreciate the post, however, you spilled an awful lot of ink complaining about conspiracy theorists rather than simply taking a stab at explaining the specific adjustments in temperature records made by the new NCDC algorithm for the 19 station in question.

There is now an ink-saving version of the above post: Just the facts, homogenization adjustments reduce global warming.