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What do the 'Climategate' hacked CRU emails tell us?

What the science says...

Select a level... Intermediate Advanced

A number of independent investigations from different countries, universities and government bodies have investigated the stolen emails and found no evidence of wrong doing. Focusing on a few suggestive emails, taken out of context, merely serves to distract from the wealth of empirical evidence for man-made global warming.

Climate Myth...

Climategate CRU emails suggest conspiracy

“[T]he 1079 emails and 72 documents seem indeed evidence of a scandal involving most of the most prominent scientists pushing the man-made warming theory - a scandal that is one of the greatest in modern science. […] emails suggesting conspiracy, collusion in exaggerating warming data, possibly illegal destruction of embarrassing information, organised resistance to disclosure, manipulation of data, private admissions of flaws in their public claims and much more.” (Andrew Bolt, Herald Sun)

In November 2009, the servers at the University of East Anglia in Britain were illegally hacked and emails were stolen. When a selection of emails between climate scientists were published on the internet, a few suggestive quotes were seized upon by many claiming global warming was all just a conspiracy. A number of independent enquiries have investigated the conduct of the scientists involved in the emails. All have cleared the scientists of any wrong doing:

  1. In February 2010, the Pennsylvania State University released an Inquiry Report that investigated any 'Climategate' emails involving Dr Michael Mann, a Professor of Penn State's Department of Meteorology. They found that "there exists no credible evidence that Dr. Mann had or has ever engaged in, or participated in, directly or indirectly, any actions with an intent to suppress or to falsify data". On "Mike's Nature trick", they concluded "The so-called “trick”1 was nothing more than a statistical method used to bring two or more different kinds of data sets together in a legitimate fashion by a technique that has been reviewed by a broad array of peers in the field."
  2. In March 2010, the UK government's House of Commons Science and Technology Committee published a report finding that the criticisms of the Climate Research Unit (CRU) were misplaced and that CRU’s "Professor Jones’s actions were in line with common practice in the climate science community".
  3. In April 2010, the University of East Anglia set up an international Scientific Assessment Panel, in consultation with the Royal Society and chaired by Professor Ron Oxburgh. The Report of the International Panel assessed the integrity of the research published by the CRU and found "no evidence of any deliberate scientific malpractice in any of the work of the Climatic Research Unit".
  4. In June 2010, the Pennsylvania State University published their Final Investigation Report, determining "there is no substance to the allegation against Dr. Michael E. Mann".
  5. In July 2010, the University of East Anglia published the Independent Climate Change Email Review report. They examined the emails to assess whether manipulation or suppression of data occurred and concluded that "we find that their rigour and honesty as scientists are not in doubt."
  6. In July 2010, the US Environmental Protection Agency investigated the emails and "found this was simply a candid discussion of scientists working through issues that arise in compiling and presenting large complex data sets."
  7. In September 2010, the UK Government responded to the House of Commons Science and Technology Committee report, chaired by Sir Muir Russell. On the issue of releasing data, they found "In the instance of the CRU, the scientists were not legally allowed to give out the data". On the issue of attempting to corrupt the peer-review process, they found "The evidence that we have seen does not suggest that Professor Jones was trying to subvert the peer review process. Academics should not be criticised for making informal comments on academic papers".
  8. In February 2011, the Department of Commerce Inspector General conducted an independent review of the emails and found "no evidence in the CRU emails that NOAA inappropriately manipulated data".
  9. In August 2011, the National Science Foundation concluded "Finding no research misconduct or other matter raised by the various regulations and laws discussed above, this case is closed".

Just as there are many independent lines of evidence that humans are causing global warming, similarly a number of independent investigations have found no evidence of falsification or conspiracy by climate scientists.

"Mike's Nature trick" and "hide the decline"

The most quoted email is from Phil Jones discussing paleo-data used to reconstruct past temperatures (emphasis mine):

"I've just completed Mike's Nature trick of adding in the real temps to each series for the last 20 years (ie from 1981 onwards) and from 1961 for Keith's to hide the decline."

"Mike's Nature trick" refers to a technique (aka "trick of the trade") used in a paper published in Nature by lead author Michael Mann (Mann 1998). The "trick" is the technique of plotting recent instrumental data along with the reconstructed data. This places recent global warming trends in the context of temperature changes over longer time scales.

The most common misconception regarding this email is the assumption that "decline" refers to declining temperatures. It actually refers to a decline in the reliability of tree rings to reflect temperatures after 1960. This is known as the "divergence problem" where tree ring proxies diverge from modern instrumental temperature records after 1960. The divergence problem is discussed in the peer reviewed literature as early as 1995, suggesting a change in the sensitivity of tree growth to temperature in recent decades (Briffa 1998). It is also examined more recently in Wilmking 2008 which explores techniques in eliminating the divergence problem. So when you look at Phil Jone's email in the context of the science discussed, it is not the schemings of a climate conspiracy but technical discussions of data handling techniques available in the peer reviewed literature. More on the hockey stick divergence problem...

Trenberth's "travesty we can't account for the lack of warming"

The second most cited email is from climate scientist and IPCC lead author Kevin Trenberth. The highlighted quote is this: "The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't." This has been most commonly interpreted (among skeptics) as climate scientists secretly admitting amongst themselves that global warming really has stopped. Trenberth is actually discussing a paper he'd recently published that discusses the planet's energy budget - how much net energy is flowing into our climate and where it's going (Trenberth 2009).

In Trenberth's paper, he discusses how we know the planet is continually heating due to increasing carbon dioxide. Nevertheless, surface temperature sometimes shows short term cooling periods. This is due to internal variability and Trenberth was lamenting that our observation systems can't comprehensively track all the energy flow through the climate system. More on Trenberth's travesty...

The full body of evidence for man-made global warming

An important point to realise is that the emails involve a handful of scientists discussing a few pieces of climate data. Even without this data, there is still an overwhelming and consistent body of evidence, painstakingly compiled by independent scientific teams from institutions across the world.

What do they find? The planet is steadily accumulating heat. When you add up all the heat building in the oceans, land and atmosphere plus the energy required to melt glaciers and ice sheets, the planet has been accumulating heat at a rate of 190,260 Gigawatts over the past 40 years (Murphy et al. 2009). Considering a typical nuclear power plant has an output of 1 Gigawatt, imagine over 190,000 power plants pouring their energy output directly into heating our land and oceans, melting ice and warming the air.

This build-up of heat is causing ice loss across the globe, from the Arctic to the Antarctic. Both Greenland and Antarctica are losing ice at an accelerated rate (Velicogna 2009). Even East Antarctica, previously thought to be too cold and stable, is now losing ice mass (Chen et al. 2009). Glacier shrinkage is accelerating. Arctic sea ice has fallen so sharply, observations exceed even the IPCC worst case scenario. The combination of warming oceans and melting ice has resulted in sea level rise tracking the upper limit of IPCC predictions.

Rising temperatures have impacted animal and plant species worldwide. The distribution of tree lines, plants and many species of animals are moving into cooler regions towards the poles. As the onset of spring is happening earlier each year, animal and plant species are responding to the shift in seasons. Scientists observe that frog breeding, bird nesting, flowering and migration patterns are all occurring earlier in the year (Parmeson & Yohe 2003). There are many other physical signs of widespread warming. The height of the tropopause, a layer in our atmosphere, is rising (Santer et al. 2003). Arctic permafrost, covering about 25% of Northern Hemisphere land, is warming and degrading (Walsh et al. 2009). The tropical belt is widening (Seidel et al. 2007). These results are all consistent with global warming.

What’s causing this heat build-up? Humans are emitting huge amounts of carbon dioxide into the atmosphere - 29 billion tonnes in 2009 (CDIAC). Greenhouse theory predicts that more carbon dioxide in the atmosphere will trap heat energy as it escapes out to space. What do we observe? Carbon dioxide absorbs heat at certain wavelengths. Satellites over the past 40 years find less heat escaping to space at these wavelengths (Harries et al. 2001, Griggs & Harries 2004, Chen et al. 2007). Where does the heat go? Surface measurements find more heat returning back to the Earth's surface (Philipona et al. 2004). Tellingly, the increase occurs at those same carbon dioxide absorption wavelengths (Evans 2006). This is the human fingerprint in global warming.

There are multiple lines of empirical evidence that global warming is happening and human activity is the cause. A few suggestive emails may serve as a useful distraction for those wishing to avoid the physical realities of climate change. But they change nothing about our scientific understanding of humanity’s role in global warming.

Intermediate rebuttal written by John Cook

Update July 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial


Expert interview with Kevin Trenberth

Last updated on 14 October 2016 by pattimer. View Archives

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The House of Commons report on the emails stolen from CRU has vindicated Phil Jones -- he has "no case to answer":

The focus on Professor Jones and CRU has been largely misplaced. On the accusations relating to Professor Jones's refusal to share raw data and computer codes, we consider that his actions were in line with common practice in the climate science community. We have suggested that the community consider becoming more transparent by publishing raw data and detailed methodologies. On accusations relating to Freedom of Information, we consider that much of the responsibility should lie with UEA, not CRU.

In addition, insofar as we have been able to consider accusations of dishonesty--for example, Professor Jones's alleged attempt to "hide the decline"--we consider that there is no case to answer. Within our limited inquiry and the evidence we took, the scientific reputation of Professor Jones and CRU remains intact. We have found no reason in this unfortunate episode to challenge the scientific consensus as expressed by Professor Beddington, that "global warming is happening [and] that it is induced by human activity"

Official statement from Climatic Research Unit (CRU)

In an interview with Andrew Freeman, historian Spencer Weart puts Climategate and the global warming skeptic phenomenon in perspective:

"...we've never before seen a set of people accuse an entire community of scientists of deliberate deception and other professional malfeasance. Even the tobacco companies never tried to slander legitimate cancer researchers."

George Monbiot reveals the most damaging email in The Knights Carbonic. Here is an excerpt, revealing the depth of the climate conspiracy:

"Then began the most hazardous task of all: our attempt to control the instrumental record. Securing the consent of the scientific establishment was a simple matter. But thermometers had by then become widely available, and amateur meteorologists were making their own readings. We needed to show a steady rise as industrialisation proceeded, but some of these unfortunates had other ideas. The global co-option of police and coroners required unprecedented resources, but so far we have been able to cover our tracks.
Our co-option of the physical world has been just as successful. The thinning of the Arctic ice cap was a masterstroke. The ring of secret nuclear power stations around the Arctic Circle, attached to giant immersion heaters, remains undetected, as do the space-based lasers dissolving the world’s glaciers.
Altering the migratory and reproductive patterns of the world’s wildlife has proved more challenging. Though we have now asserted control over the world’s biologists, there is no accounting for the unauthorised observations of farmers, gardeners, bird-watchers and other troublemakers. We have therefore been forced to drive migrating birds, fish and insects into higher latitudes, and to release several million tonnes of plant pheromones every year to accelerate flowering and fruiting. None of this is cheap, and ever more public money, secretly diverted from national accounts by compliant governments, is required to sustain it."

Another amusing parody is Newtongate: the final nail in the coffin of Renaissance and Enlightenment ‘thinking’ which scrutinizes the private correspondance of Isaac Newton to cast doubt on Newtonian physics and integral calculus.

MediaMatters examines many of the claims coming out of "Climategate", exposing how the emails have been distorted and misrepresented.


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Comments 76 to 81 out of 81:

  1. What has become obvious to me is that all denialist arguments boil down to "It's a Hoax". Whatever the argument that a denialist is throwing out, it is something that the climate science community has already heard and refuted. The authors of the IPCC reports have also heard all of these arguments before. Therefore, the only way to continue to be a denier is to believe that the vast majority of scientists studying climate are wrong, or involved in the most elaborate international hoax in the history of the world. Clearly these views are irrational, and require a strong prediliction to deny climate changed usually based on ideology.

  2. Hilarious. ignore what they did and focus on the fact that a Board "cleared them".

    About as persuasive as when the police review board clears a police officer for shooting people without proper cause.

    the hockey stick and climate gate emails are scandalous. they cherry picked the series they wanted, deleted embarrassing data, and sticky taped it all together to produce the most compelling picture they could.

    it singlehandedly did more to undermine climate science than anything else.

    and we see no acknowledgement. No contrition. Just this whitewalling garbage that "they were cleared".


    and you wonder why people have doubts?


    [DB]  Repeated sloganeering snipped.

  3. Hi,

    in your article above you portray Climategate as follows: "Focusing on a few suggestive emails, taken out of context ..."

    After some minutes of googling I came across this article from the renowned british newspaper "The Telegraph" (in case someone doesn't know: the weekly version of "The Daily Telegraph"): LINK

    Citation: "There are three threads in particular in the leaked documents which have sent a shock wave through informed observers across the world. Perhaps the most obvious is the highly disturbing series of emails which show how Dr Jones and his colleagues have for years been discussing the devious tactics whereby they could avoid releasing their data to outsiders under freedom of information laws."

    The article also says that this scandal goes right to the heart of the IPCC: "Professor Philip Jones, the CRU's director, is in charge of the two key sets of data used by the IPCC to draw up its reports."

    The problem is that these pictures given differ so geatly that there is only one explanation: One side must be lying like a trooper.

    If the author of the article, columnist Christopher Booker, and the colleagues he is referring to, are all lying, he and them must have made up their accusations, that means the emails and the years of deceit do not exist, it is all invented. Or he misread the emails, he and his colleagues are just stupid. Or, on the other hand, climate alarmists are defending their cause by playing down a terrible scandal. Everyone shall decide for their own, which is more probable.

    The start page I read here was quite good and you made some interesting points I eventually will investigate on further. But here, talking about Climategate I once more come to the conclusion that Skeptics sometimes aren't quite that skeptic at all but love to trust in what authorities proclaim, without checking the facts.


    [DB] Shortened and activated URL.

  4. Booker is not a reliable source. The mining/fossil fuel stooge S. McIntyre years ago launched a harassment campaign by asking multiple followers to file FOI requests, directed against scientists whose work he disliked. Because they knew that the requests were not a good faith effort, the recipients were reluctant to release information, which unfortunately escalated to whole thing in a away that then became easy to exploit for the bad faith actors. It can certainly be said that Jones and others could have handled this better, and that was one of the conclusions of the investigation. Whomever can be perfect all the time when faced with bad faith attacks can throw the first stone.


  5. It is worth noting that the Telegraph is a Murdoch paper and, like all other tentacles of the Murdoch's empire, used to foster its boss' ideology. In any circumstance, I would give it only the credence it deserves. 

  6. "... there is only one explanation: One side must be lying like a trooper."

    That is a real logic failure there. I can think of at least two more explanations that would fit those criteria.

  7. There are some quotes from emails sent on September 9th 1999 which are frequently brought up by conspiracy theorists that don't seem to be discussed here. Forgive me if I have simply missed discussion of them. They regard the divergence of Keith Briffa's tree ring reconstruction from Mann and Jones.

    IPCC author Chris Folland writes "A proxy diagram of temperature change is a clear favourite for the Policy Makers summary. But the current diagram with the tree ring only data somewhat contradicts the multiproxy curve and dilutes the message rather significantly." 

    Briffa writes there is "pressure to present a nice tidy story as regards ‘apparent unprecedented warming in a thousand years or more in the proxy data…,’”

    Mann writes "Everyone in the room at IPCC was in agreement that this was a problem and a potential distraction/detraction from the reasonably consensus viewpoint we’d like to show w/ the Jones et al and Mann et al series"

    This has been used to suggest that the IPCC is after particular data to support a message which it will pressure scientists for, and the IPCC will ideally exlude data which 'dilutes' the message. I don't believe that but it's become a common talking point.


    [BL] The tendency for contrarians to take email quotes out of context is well known.

    Two additional myth rebuttals at SkS cover parts of this discussion, and reference material from Briffa:

    Climategate and the peer review process

    Were skeptic scientists kept out of the IPCC



  8. Thanks for the quick response.

    The article 'Were skeptic scientists kept out of the IPCC' shows evidence that the working group did not suppress contrarian papers but honestly critiqued them, hence it can be argued that they also honestly critiqued Briffa's tree ring data (and from what I know, they did indeed and there was a detailed discussion of Briffa's tree ring data in the report). But someone making the argument I laid out in the above post might still say the quotes, including apparently quite explicit ones from Briffa himself, are evidence of improper pressure to create consensus rather than uncertainty for the policy makers, even if in this case there was ultimately no impact on the results. As you say, I think there's a good chance the quotes are taken out of context like so much of the selective quoting done by 'Climategate' proponents, but if they have been I can't find any material showing how they have been taken out of context.

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