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A recent post here by Anthony Cox and Joanne Nova claims to "disprove" Anthropogenic Global Warming (AGW). It is a useful post, because it assembles the cream of contrarian argument in one place.
The use of these papers illustrates the "Zombie Effect" in contrarian science: their papers get refuted by climate scientists, but they continue to be quoted by contrarians in the media and in the blogosphere as if the refutation did not take place. The aim is not to establish truth, but to maintain an impression.
1 Lindzen and Choi
They begin with Lindzen and Choi 2011, dealt with here.
2 Spencer and Braswell
Dealt with here.
3 Ocean Heat - Knox and Douglass
An interesting paper by Knox and Douglass (KD12). Climatologists say that heat is being stored in the oceans. K&D claim to show that more radiative energy has been leaving the ocean than being stored in the oceans.
Their claim is rebutted by Nuccitelli et al here.
Basically KD12 looked at 700 metres of ocean, whereas Nuccitelli looked deeper, to 2000 metres. This shows that the ocean heat content continues to rise.
|From Nuccitelli et al. (2012).|
There is more on ocean heat content here, which shows there is more heat stored even deeper than 2000m, and also that the time period chosen by KD12 was badly chosen. The conclusion: "Douglas and Knox is a fundamentally flawed paper, whose conclusion rests wholly upon analysing only carefully selected short-term periods which the authors preferred."
4 Novel theory - Miscolczi
The fourth evidence put forward by Cox and Nova is that of Miscolczi here and here.
He uses his own highly complex model to create a new "law" for the greenhouse effect which claims that the effect does not change over time, and then deduces that his law fits the data.
Significantly, Roy Spencer, one of the contrarians who is a real scientist, does not agree with him.
Miscolczi is comprehensively refuted here, and a layperson summary is here. Basically, his "law" does not fit the facts. There is no reason that the greenhouse effect should not vary over time, since it depends on the composition of the atmosphere.
5 Statistics- McShane and Wyner 2011
These statisticians gave a workover to the material of the Hockey Stick temperature records, and conclude that the uncertainties were greater than is generally thought.
Lazarus summarises here, "the major point and problem with this paper were that the results still showed a ‘hockey stick’ indicating current warming was pretty anomalous and that the authors were not climatologists,"
This is an intensely technical statistical matter, and the nearest I can find to a clear critique is here.
Deep Climate has a fuller and stronger critique here.
RealClimate gives a review here which is a technical discussion rather than a full on rebuttal, appropriately since the paper is a review of statistical methods.
McShane and Wyner conclude “our model gives a 80% chance that [the last decade] was the warmest in the past thousand years”…, so it hardly qualifies for being another FINICOF (final nail in the coffin of agw).
6 The Tropospheric Hotspot
Cox and Nova point to papers which indicate that climate models overestimate the warming that will occur in the air above the tropics as a result of global warming. They cite McKitrick, McIntyre and Herman 2010, Fu Manabe and Johnason 2011, and McKitrick and Vogelsang 2011.
I summarise the response from Skeptical Science here.
This argument hinges on the contrarians' misunderstanding of the prediction of what greenhouse warming will do. The scientific prediction is that the stratosphere will cool while the troposphere warms. Observations confirm this stratospheric cooling - though CFC destruction of ozone is also contributing to the cooling.
Any warming - whether from solar or greenhouse - will increase tropospheric temperature.
Having said that, the models do predict increased warming with height. Radiosonde data (from instruments attached to weather balloons) shows less warming than expected, or even cooling. This may be due to difficulty with the radiosonde data. Radiosondes were designed for weather predictions, not for more long-term climate predictions.
Indirect estimations of temperature from wind data and precipitation shows more agreement with the models.
My opinion, fwiw, is that I feel uneasy about the discrepancy between models and observations, but confident that further work will reduce the gap, either by improving the data, or improving the models, or both. In the end, the discrepancy is not (as contrarians would claim) another FiNICof (final nail in the coffin of agw), because it relates to difficulty in predicting the atmospheric response to warming from any source.
6a Climate shift
I have put this in as 6a because the topic is not given a separate category by Cox and Nova, but deserves its own treatment. It is presented by Cox here.
John Cook has a very helpful discussion on climate regime shift here. The key point is "Climate shifts do not stop the planet's energy imbalance. They merely cause temporary slow downs or speeding up of surface temperature warming."
This is a good point to go look at John's excellent "Escalator", showing the variable nature of the continuing increase in global temperatures.
7 Climate Models Koutsoyiannis et al. 2008 and 2011
He shows that predictions from four models bear very little relation to observed conditions in specific locations over periods of 100 years.
Gavin Schmidt at Real Climate argues that taking the regional part of the models is bound to invalidate them. "The answer to their effective question – are very local single realisations of weather coherent across observations and models? – is no, as anyone would have concluded from reading the IPCC report or the existing literature. This is why no one uses (or should be using) single grid points from single models in any kind of future impact study. "
He points to a different approach which seem to show a different result.
Here is Skeptical Science on climate models.
I have pointed to a few rebuttals to Cox and Nova's (C&N) best endeavour attempt to refute anthropogenic global warming.
They have failed to falsify the AGW theory.
On the other hand, they have not attempted to make their own hypothesis stand up.