Debate on climate change far from over
The UN panel from which governments get their information is deeply flawed, writes Economics editor Alan Wood
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July 19, 2006
AT lunchtime on Monday, John Howard and Victoria's Steve Bracks were on their feet talking about energy, climate change and the environment. While their approaches were notably different, there is one thing on which they both agree: the UN's Intergovernmental Panel on Climate Change is the font of all scientific wisdom on global warming.
In fact it has become quite fashionable of late to assert the global warming debate is over and an overwhelming scientific consensus prevails. This is simply untrue.
As acknowledged in an Australian Bureau of Agriculture and Resource Economics report on climate change scenarios, also released on Monday, there are still considerable scientific uncertainties surrounding the nature and extent of future climate change.
A report released in the US on Friday has torn apart one of the main props used by the IPCC to illustrate the need for urgent action on climate change. The report raises serious questions about the IPCC process and the findings on which world governments rely in forming their climate change policies. First, some background.
In telling the global warming story the IPCC, since 2001, has relied very, very heavily on what has become known as the "hockey stick". It is based on a 1999 paper, the principal author of which was paleoclimatologist Michael Mann.
Before the publication of his paper the generally accepted view of the past 1000 years was that there was a period of elevated temperatures known as the Medieval Warm Period, which was followed by the Little Ice Age, and then a new period of global warming.
Mann's hockey stick eliminated the Medieval Warm Period, flattening the fluctuations in global temperatures over most of the past millennium (the blade of the hockey stick) until we get to the 20th century, where the rate of global warming takes off in a sharp upward surge (the handle of the hockey stick).
This is the basis for the IPCC claim, now widely accepted, that the 20th century was the warmest in the past 1000 years, the 1990s were the warmest decade in the past millennium, and 1998 was the warmest year in the past 1000 years. Scary stuff!
Two Canadians, Steve McIntyre, an engineer, and Ross McKitrick, an economist, challenged Mann's work in 2003. They argued his technique produced hockey sticks from just about any set of data. Mann responded in a notably less than scientific manner by withholding adverse statistical results and important data, and discouraging the publication of criticism of his work.
A Wall Street Journal report of the controversy last year attracted the attention of the US House Committee on Energy and Commerce. It wrote to Mann and his co-authors, as well as to the IPCC, demanding relevant information and then approached independent US statisticians for advice on assessing the data provided.
Leading US statistician Edward Wegman, of George Mason University, who is chairman of the US National Academy of Sciences' committee on applied and theoretical statistics, agreed to assemble a group of statisticians to assess the Mann data. Their report was released last Friday and supported McKitrick and McIntyre's criticisms of the hockey stick, finding Mann's statistical work flawed and unable to support the claims of the hottest century, decade and year of the past millennium.
Yet the IPCC used the hockey stick in its publications, media releases, press conferences - where senior IPCC figures sat with the chart as a backdrop - and, for a time, incorporated it into the IPCC's logo.
It is important to understand that this is a debate about the use of statistics. Mann did no original scientific work, using available data and manipulating it in a new way.
However, it destroys the idea of an alarming escalation in global temperatures and, as the Wall Street Journal remarked on Friday, brings the present temperature rise within the range of natural historical variation.
There remains plenty of room for argument about the projections of future temperature rises and their implications, based on what are still primitive climate change models. But there is no escaping the damage done to the IPCC's reputation. It has relied heavily on a badly flawed piece of work, produced by what Wegman discovered was a small, insular group of paleoclimatologists who incestuously peer review, reinforce and defend each others' work.
Significantly, former commonwealth statistician Ian Castles and his colleague David Henderson, former head of the Organisation for Economic Co-operation and Development's economics department, have also exposed statistical and analytical flaws in the economic scenarios underlying the IPCC's climate change projections. As with McIntyre and McKitrick's criticism of the hockey stick, the IPCC establishment initially tried to ignore, then discredit, their work.
However, last year a House of Lords committee looking at the economics of climate change praised their work and said that without them the debate on emissions scenarios would not have taken place.
The Lords committee also expressed concerns that the IPCC was an increasingly politicised body that tried to suppress dissent. It warned of a risk it was becoming a knowledge monopoly, "in some respects unwilling to listen to those who do not pursue the consensus line".
In an article last week in Canadian newspaper the National Post, McIntyre and McKitrick say the IPCC's lead author, who selected Mann's hockey stick for prominent display, was none other than Mann himself. They quote eminent US climate science academic Kurt Cuffey as saying the IPCC's use of the hockey stick sent "a very misleading message".
They ask a pertinent question.
If the IPCC process isn't fixed, and there is no evidence the IPCC intends to do anything about it, how do we know it won't send out another very misleading message in its upcoming Fourth Assessment report?
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