Garnaut Report Due

The Garnaut report on regulating carbon emission is due to be made public today. According to The Australian, Professor Garnaut’s 600-page report will provide detailed analysis of how climate change will affect the Australian economy and what should be done to combat the issue. The article mentions emissions trading scheme, black-outs, bankruptcies and spiralling power bills.

Along with 4000 others, I made a submission on the Interim Report, argued the case for more involvement of statisticians, and supported with a summary of the sensitivity testing and conversations with Rahmstorf on this blog. The one page article published in Science, claimed to show that the climate was responding at a faster rate than the climate models predict. Ironically, the publication marked the start of over 12 months decline in global temperatures dubbed ‘Rahmstorf’s drop‘. I think it is supposed to be getting warmer, not colder.


We looked at this article in detail here. In a series of exchanges with Rahmstorf documented here, it was apparent that the uncertainty was too large to support the claims made by Rahmstorf et al. 2007, and that he had no idea how the dubious, ad hoc end-point smoothing procedure worked. Despite its obvious severe limitations, Ramstorf et al. 2007 was the sole citation for the climatic basis for prompt and extreme action on carbon emissions. It will be interesting to see how Garnaut thinks climate change will affect the Australian economy, if Rahmstorf’s drop continues to bring lower global temperatures and more anomoly posts.

Update: The Garnaut Report has been released, if you can get a connection from their server. It appears they performed some original statistical analysis, but did not attempt to review the quality of evidence provided by existing work. The preface reports work that looks alot like lucia’s:

The dissent took a curious turn in Australia in 2008, with much prominence
being given to assertions that a warming trend had ended over the last decade.
This is a question that is amenable to statistical analysis, and we asked
econometricians with expertise in analysis of time series to examine it. Their
response, that the temperatures recorded in most of the last decade lie above
the confidence level produced by any model that does not allow for a warming
trend, is reported in Chapter 5 (Box 5.1).

Chapter 5 box summarises:

There has been considerable debate in recent
months on the interpretation of the global temperatures over the past
decade. Questions have been raised about whether the warming trend
ended in about 1998.
To throw light on this question, the Review sought assistance from
two eminent econometricians from the Australian National University
to investigate the question. Trevor Breusch and Farshid Vahid have
specific expertise in the statistical analysis of time series—a speciality
that is well developed in econometrics. They were asked two
questions:
• Is there a warming trend in global temperature data in the past
century?
• Is there any indication that there is a break in any trend present in the
late 1990s, or at any other point?
They concluded that:
It is difficult to be certain about trends when there is so much variation
in the data and very high correlation from year to year. We investigate
the question using statistical time series methods. Our analysis shows
that the upward movement over the last 130–160 years is persistent and
not explained by the high correlation, so it is best described as a trend.
The warming trend becomes steeper after the mid-1970s, but there is no
significant evidence for a break in trend in the late 1990s.Viewed from the
perspective of 30 or 50 years ago, the temperatures recorded in most of
the last decade lie above the confidence band produced by any model that
does not allow for a warming trend (Breusch & Vahid 2008).

References

Global temperature trends – Breusch and Vahid (ANU) 2008[1].pdf

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0 thoughts on “Garnaut Report Due

  1. They seem to have rephrased the question in such a way as to make the answer more favorable. Late 90’s could mean since 95 or 99 or whatever. However, accounting or El Ninos and La Ninas, as well as the solar cycle probably does restore the trend-but to exactly the same rate as the previous two decades or so showed-a constant, not accelerating, trend. Rahmstorf appears to be misleading, as (1) 2005, was an El Nino year, an is the second to last year in the record, and (2) that same year fell almost ~exactly~ on the linear tredn line!
    http://www.worldclimatereport.com/index.php/2006/01/31/hot-tip-post-misses-the-point/
    There is ~no~ evidence for either acclerating warming, or for the rate being greater than expected. I think that an objective analysis, of the most rcent data would find no trend from January 1998 to now, but also agree that the trend is not significant (at least not yet) because(1) the time period is to short and (2)the end points have at least one significant internal oscillation at opposite signs on each end of the trend line.

    However, much more interesting is Ocean Heat Content, which has been flat or a while:

  2. They seem to have rephrased the question in such a way as to make the answer more favorable. Late 90’s could mean since 95 or 99 or whatever. However, accounting or El Ninos and La Ninas, as well as the solar cycle probably does restore the trend-but to exactly the same rate as the previous two decades or so showed-a constant, not accelerating, trend. Rahmstorf appears to be misleading, as (1) 2005, was an El Nino year, an is the second to last year in the record, and (2) that same year fell almost ~exactly~ on the linear tredn line!
    http://www.worldclimatereport.com/index.php/2006/01/31/hot-tip-post-misses-the-point/
    There is ~no~ evidence for either acclerating warming, or for the rate being greater than expected. I think that an objective analysis, of the most rcent data would find no trend from January 1998 to now, but also agree that the trend is not significant (at least not yet) because(1) the time period is to short and (2)the end points have at least one significant internal oscillation at opposite signs on each end of the trend line.

    However, much more interesting is Ocean Heat Content, which has been flat or a while:

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