This article, by N.G. McCrum (a pseudonym, I'm guessing a chemist an engineer!) was originally published in the Oxford Magazine, a publication distributed to university staff. I am reproducing it here with the permission of the publisher. It is the sequel to an earlier article.
A second letter to a Climate Correspondent: the Rise and Fall of the Hockey Stick
My dear Fiona,
I have just read your first essay as climate correspondent in today’s London Sentinel and my pride in your achievement on reaching this pinnacle is immense but tempered with a nagging worry. My dear, your background knowledge is appalling! As your aunt and a retired press officer in the Department of Energy and Climate Change, I am e-mailing you quickly to give you warning that your ignorance has led you into a terrible blunder.
For years The London Sentinel has been blessed with a well informed, fashionably green, rancorous band of readers who believe wholeheartedly in anthropogenic global warming (AGW). In your ignorance, you have deeply offended them by use of a coarse girls’ school sporty image, “a lot of old hockey sticks”. Your editor already will be inundated with unpleasant letters. I do hope he stands by you. In the event he doesn’t, your old university seems to be filling up with climate journalists. Do let me know, I may be able to help. I have heard some of the appointments come with Dining Rights.
For believers in AGW, the term hockey stick is today highly offensive. Deniers, of course, use it all the time, and indeed sell tea towels and coffee cups embellished with images of multicoloured ice hockey sticks on the internet! They can be used as gifts to be sent to AGW believers to annoy and intimidate.
For me, “hockey stick” invokes memories of the heyday of our cause, the dawn of this century and the sad decline since that happy time. The new President of the Royal Society spoke movingly on TV on this subject in January, especially on the possibility of legal action against our hockey stick scientists! Let me tell you the story.
The hockey stick is a nickname for a pair of intersecting lines on a graph, a plot of global temperature against time, year by year since the time of the Norman supremacy. It carries a simple message. The long handle is nearly horizontal and indicates that from near 1000 to 1900 AD global temperature showed little change: the short blade is close to vertical indicating a rapid temperature increase from 1900 to 2000 AD.
It purports to be a reconstruction of global temperature from tree rings, corals and other time/ temperature markers, with the emphasis on tree rings. The abrupt transition in rate of temperature change–from reasonably steady to rapidly increasing–coincides with the release of increasingly massive amounts of industrial CO2 around the turn of the twentieth century. It was given the blessing of the IPCC (Intergovernmental Panel on Climate Change) in 2001.
The hockey stick became the glorious icon of our crusade and under its banner the western democracies were conquered. There were no deniers in those days. Denial was equated to knife crime or even crimes against humanity. The Gore film won, not a trivial Oscar, but a Nobel Prize!
The hockey stick made its debut in the prestigious journal Nature in 1998 and became the triumphant icon of the AGW movement three years later. In the superlative text of the IPCC report of 2001 the hockey stick graph was printed in no less than six places. Throughout the whole of the introductory conference for the press, the distinguished chairman, Sir John Houghton, arranged to be seated under a screen showing a huge “blown up version” according to that scintillating book by Christopher Booker, “The Real Global Warming Disaster.” This book is, of course, proscribed literature, but so well written and interesting I find myself dipping into it from time to time.
Why in 2001 was the hockey stick received by all believers in AGW with rapture? The answer is that it rescued our crusade from a false step. A decade earlier the IPCC thoughtlessly declared that the global temperature went up and down like a yo-yo every four or five hundred years. In this they followed the life’s work of Hubert Lamb, the distinguished founder of the celebrated CRU (Climate Research Unit) at UEA.
There was a warm and fruitful time, the Mediaeval Warming–Viking vineyards in Iceland (or was it Yorkshire?). There was a cold and hard time–the Little Ice Age, Pepys and Charles II dodging horses and carts in London on the frozen Thames. According to this view, the earth today is still warming up from the Little Ice Age and has a long way to go to reach the high temperatures attained during the Mediaeval Warming. However, this model of a fluid yo-yo global temperature is divorced from any man made surge of CO2. It contains no human input whatsoever, which all right thinking people now accept.
Thankfully this fairy tale was swept away by the hockey stick. The Mediaeval Warming and Little Ice Age did not exist! They were a figment of the scientific imagination, the faulty product of non-quantitative evidence: manor house records, ships’ logs, church records, vineyard records, the scribblings of obscure poets, diarists and monks. All had to submit to the findings of a brilliant young physicist, Michael Mann, and his team.
It’s no wonder the AGW theorists were overjoyed. As the industrial output of that frightful poison CO2 accelerated with the dawn of the twentieth century, it stands to reason there must be an associated warming and this was detected by Michael Mann with his discovery of the hockey stick graph. Everything fitted together! Trust a young physicist to get it right when the more staid disciplines geology, history, etc. were all on the wrong track.
Political action shot ahead after the advent of the hockey stick. As a logo it is perfection–essentially minimalist, rather like a back to front Nike logo. It was, of course, carefully sculpted to have instantaneous visual impact–you don’t get that kind of class without human intervention. Its elementary power and simplicity stimulated big advances: the Gore book, film and Nobel prize, the growth of the carbon credit industry, a copious flood of excellent propaganda narratives in film, television and newspapers and acceptance of the AGW hypothesis by the political parties.
Of course, icons can fail! You are too young, I think, to remember the Christmas icon of the most magnificent of Tokyo shops, which was a crucified teddy bear! What seemed chic, cool and deliciously edgy at first soon turned very sour! And so it was with the hockey stick.
Thankfully the fall of the hockey stick from prestigious icon to sad joke was slow and this left it in possession of the field for a few years, long enough for the politicians to take what I trust is irreversible action. Nevertheless events as they unfold are not going our way. The hockey stick is in extremis: it could be finished off by a legal challenge. Our side is tight lipped about it but this is the truth. Why else would the President of the Royal Society spend one hour on TV trying to mend the damage done by the e-mails which leaked from the CRU Laboratory. A strong legal case mounted against the hockey stick would really let the rocket off.
The destruction of the hockey stick and humiliation of Michael Mann is the work of a wrecking-gang led by a semi-retired Toronto minerals consultant, Stephen McIntyre. It pains me to have to tell you he is an old member of your college Corpus Christi, and he read PPE as you did. I do earnestly entreat you not, on this account, to give him an easy ride in your column.
McIntyre’s attack on the hockey stick has been sustained and highly successful. His academic background (mathematics and PPE) is perfect as is his long practised expertise in ferreting out crooked prospectuses from mineral-exploration companies out to defraud investors on the Toronto stock exchange with ersatz hockey sticks. He first saw the hockey stick graph (global warming variant) in propaganda materials distributed by the Canadian government. “What struck me is it looked very promotional and I wanted to see how they made it,”1 was his immediate reaction, which started him on his dastardly work of sabotage.
McIntyre’s desire to have a proper audit of research is encapsulated in the phrase, ‘Give me a break, we are making billion dollar decisions here’.1 I have to say, he did indeed prove that the hockey stick had not been scientifically audited, either by the reviewers for Nature or later by the IPCC committees: neither had sent for the numerical data; neither was paid to audit! What do you expect? I will return to this sore point which is constantly on my mind, even in my dreams: indeed it is the source of my recurring nightmares. Some clown has invested my pension funds in carbon credits thinking I would be pleased.
McIntyre’s range of expertise includes the statistical procedures used by the hockey stick team to produce the hockey stick from a dense swarm of data points. Apparently this procedure is called ‘principal component analysis’ and can produce hockey sticks from telephone directory numbers unless used correctly!
In addition some trees, the bristlecone pine, for example, can generate the hockey stick but most trees don’t!
In initiating an experiment, it is not necessary to invest in mountain boots, scarves and a woolly hat. There are libraries of data on the internet. The team has merely to select the desired data: the term desired is crucial, which brings up the topic of cherry picking!
Although the term cherry picking is not a word you will find in learned journals, the President of the Royal Society used it several times in his television discourse on the hockey stick. He used it exclusively to criticise the actions of bloggers in selecting evidence. If you cherry pick evidence you can mould a result but nobody will be persuaded.
Cherry picking of trees is normal practice in dendroclimatic studies. This astonishing fact is made clear by Professors Jacoby and D’Arrigo of Columbia University. As a general statement it is hard to beat D’Arrigo’s laconic remark: “cherry picking is necessary if you want to make cherry pie”.2 Her colleague Jacoby points out that it is a “waste of funding agency and tax payer dollars” not to reject data that fails to tell a “good climatic story”.3
A frightful fuss has been made about the fact that the hockey stick data at the highest temperatures, the blade, was obtained from conventional thermometry and not from tree rings. You may remember that each year produces a ring and the separation, ring to ring, reflects the temperature at which the wood grew, the wider the separation the higher the temperature. This follows because new wood is laid down each year in the growing season at a faster rate the higher the temperature. But growth rate depends on other factors, for instance CO2concentration. In the latter half of the twentieth century it was clear that the temperature was rising as measured by conventional thermometers, but tree ring separation stated the opposite!
The hockey team could have stayed with the temperature according to tree rings but they did not. For this small region of temperature, forty degrees or so, they used conventional thermometry but for the other thousand years or so they used ring separation. That is, they chose to replace the inconvenient later tree data with more suitable data from other sources. The trouble is that the uptick in the twentieth century, the stubby blade of the hockey stick, is the crucial result! So it might be argued, and is by deniers, that to use tree rings up to the year 1960 and then switch to normal thermometry is asking for trouble especially if you don’t make it clear that this is what you have done, which is a fair description of the actions of Mann’s team.
Well, all this came out in the Climategate e-mails, which will resonate for many years: “I’ve just completed Mike Mann’s Nature trick of adding in the real temperature to each series for the last twenty years (from 1981 onwards) and from 1961 for Keith Briffa’s to hide the decline.”4
This “hide the decline” is the sculpting I described earlier. If it had not been done Mann would have had a declining line, no hockey stick icon, no promotion of the cause and big trouble with the sponsor.
A cheery but coarse group of folk singers, ‘The Minnesotans for Global Warming’, have a song with a scandalous first verse:
Makin’ up data the old hard way
Fudgin’ the numbers day by day
Ignoring the snow and the cold and the downward line
Hide the decline, hide the decline.
In my view, the hockey stick has served its purpose. If I were you, dear Fiona, I would never introduce the word hockey stick into your essay again. It is a very touchy issue indeed. Let ‘the Minnesotans for Global Warming’ have their fun singing their folk songs. And we can have ours supporting the price of carbon credits by baking a good cherry pie. You know the kind of thing, very traditional fare: polar bears with cuddly cubs on minute ice flows, horrific computer predictions for temperatures in the year 2200AD and quotations from David Attenborough.
You might also try through your column to nudge the Royal Society back to its customary role, in which for centuries it has excelled, that of wise, austere and impartial referee quite divorced from politics and pseudo-moral attitudes. The President of the Royal Society on television approved of Phil Jones’s actions. If a court decides otherwise, either here or in the USA, the Royal Society will be wrong and the Minnesotans for Global Warming right! What is the point in risking so many years of supreme cultural capital in such a dubious cause? The evidence from the hockey stick adds nothing today to the case for man-made global warming.
Your loving Aunt Hermione
PS Fiona, if you wish to read more on this, see the excellent “The Hockey Stick Illusion” by A W Montford published in 2010.
1 is from Antonio Regalado in The Wall Street Journal, February 14 2005:
2 and 3 are from The Hockey Stick Illusion, pages 235 and 236:
4 is from the celebrated leaked e-mail of November 20 2009, from Phil Jones to the original hockey stick authors, M. Mann, R. Bradley and M. Hughes.
A first “Letter to a Climate Correspondent” appeared in Oxford Magazine, No 298, Hilary Term, 2010–ed