Climategate 2: A consensus emerges
Anthony Cox
The latest batch of emails from the University of East Anglia [UEA] has been released and has produced the usual stark divisions in response. The pro global warming side [AGW] state they have been taken "out of context" and invest the release with the usual nefarious financial motives.
The sceptics are naturally outraged.
However the second release should be seen as an opportunity, not an intensification and widening of the gap between the pro and anti-AGW camp.
In legal disputes about complex matters, the parties can be obliged to prepare a Statement of Agreed Facts which acts to narrow the dispute down to its essential elements.
The latest emails reveal several issues which show the position of the email authors and the sceptics are very similar. Given this welcome convergence of opinion, a Statement of Agreed Facts can be prepared showing what aspects of AGW are essentially resolved and which issues remain in contention.
1. The Tropical Hot Spot [THS]. The THS is an essential element of AGW theory; AGW says more CO2 in the atmosphere will cause more evaporation and since water is a powerful green-house gas the extra water will cause greater warming. This will be most pronounced in the Tropical atmosphere since the Tropics have the most water.
In email 1939 Peter Thorne, a prominent AGW scientist says:
Observations do not show rising temperatures throughout the tropical troposphere unless you accept one single study and approach and discount a wealth of others.
Despite Thorne's reservations the IPCC published a major diagram, Figure 9.1, in its 2007 AR4 report purporting to show a THS caused by greenhouse gases. As is plainly visible the pattern of a THS from greenhouse gases is very different from Tropical heating caused by other factors.
Thorne has contributed to two other major studies on the THS done after AR4. In the first study in 2008 Thorne et al concluded that the model predictions and observations about a THS were in good agreement and that pre 1979 radiosonde temperature data, which is from weather balloons, had been responsible for any disagreement.
In his second 2011 study Thorne et al concluded that the observations since 1979 disagreed with the model predictions but when the observations from the radiosondes from 1958 were added the models and observations were in reasonable agreement.
Everyone is allowed to change their minds.
However, Thorne's latest paper disagrees, in varying ways, with studies by Paltridge 2009, Christy et al 2010, McKitrick et al 2010, McKitrick et al 2011, McKitrick et al 2011 and Fu et al 2011.
So, this is the first agreed fact between AGW scientists and sceptics; there is no THS “unless you accept one single study” which is Thorne’s.
2. The Hockeystick [HS]. The HS is another essential part of AGW theory because it is a temperature record stretching back 2000 years which shows temperatures in the last 60 years are the warmest. If the HS is wrong then it cannot be claimed with certainty that current temperatures are the warmest.
The seminal HS study is by Michael Mann et al in 1999. Mann used tree-rings as a substitute for thermometers. Converting tree-rings to temperature is a bit of an art and can depend on what tree-rings you use. One of Mann’s original co-authors, Ray Bradley, in email 4207, had this to say about Mann’s selection of tree-rings in writing a follow up paper in 2002:
You commented that the Chinese series of Yang et al (GRL 2002) looked weird. Well, that’s because it’s crap.
In fact Mann's HS has been critiqued not only because of what tree-rings he used but also the statistical methods he used. McShane and Wyner look at both of Mann's HS studies and find that even if you use Mann's tree-rings you still can't say today's temperatures are the warmest.
So this is the second agreed fact; the HS is "crap".[/b]
3. The climate models and clouds. Clouds reflect heat from their tops and "trap" heat underneath them. Clouds cover the globe. Understanding the net effect of clouds on temperature and whether they cool or warm, is crucial to understanding whether AGW adds to temperature.
In email 4443 the head of the UEA's Climate Research Unit [CRU], Phil Jones said this:
Basic problem is that all models are wrong- not got enough middle and low level clouds. Problem will be with us for years, according to Richard Jones.
That was in 2004. Have the models got better? The models in 2009 concluded that the net effect of clouds is to warm. That has been modified by Dessler 2010 who says that even a slight cooling by clouds cannot offset warming from AGW.
The problem with the above papers is that observations, what actually happens in the real world, are contradicting the models. In the real world clouds cool. This was known as far back as 1989 in a study by the doyen of clouds, Ramanathan.
Ramanathan has been subsequently confirmed by Spencer 2007, Dupont 2008, Lindzen and Choi 2011, Allan 2011 and Spencer and Braswell 2011.
All of these papers contradict the models. So, this is the third agreed fact: the models are wrong; they don't have enough clouds.
4. Natural variability [NV]. NV is the change in weather patterns which occurs as a result of the change between El Nino which is hot and dry and La Nina, which is cool and wet. The position of AGW science was that the effect of AGW dominated NV and temperature increased as a result.
The emails show some diverse views about NV; for instance in email 1255532032 the UEA scientists, in an attempt to reach their own agreed facts, regard NV as a rather meaningless term. In email 4548 NV had greater importance.
When McLean, De Freitas and Carter suggested NV could explain temperature they were hailed down by many of the AGW scientists.
Now it seems that NV is accepted at the highest levels of AGW science. So, this is a fourth agreed fact; that NV dominates climate.[/b]
That leaves what is still in disagreement between AGW supporters and sceptics. There appears to be just one area of disagreement.
1. Peer Review. Professor Lewandowsky probably sums up the AGW public view of peer review best. Of particular interest is his comment:
Science is also resilient to wilful subversion of the scientific process.
Email 3052 presents a slightly different approach, the private view of AGW. In this email Professor De Freitas is accused of promoting "fringe views". The irony is that De Freitas was a co-author of the NV paper which is now the AGW view. In respect of his "fringe views" he has otherwise been vindicated.
In a way, therefore, Lewandowsky is correct; the attempt to wilfully subvert the science of De freitas has failed.
So, it would seem that even this area of disagreement between AGW and sceptics can be resolved.
The leaker of the emails has indeed performed a public service in bringing together such disparate groups.
Note: Hyperlinks to references available on original article at:
http://www.abc.net.au/unleashed/3707172.html
