There is currently a difference in approach to climate science between the sceptical Baconian - empirical appraoch solidly based on data and the Platonic IPCC approach - based on theoretical assumptions built into climate models.The question arises from the recent Muller - BEST furore -What is the best metric for a global measure of and for discussion of global warming or cooling. For some years I have suggested in various web comments and on my blog that the Hadley Sea Surface Temperature data is the best metric for the following reasons . (Anyone can check this data for themselves - Google Hadley Cru -- scroll down to SST GL and check the annual numbers.)
1. Oceans cover about 70% of the surface.
2. Because of the thermal inertia of water – short term noise is smoothed out.
3. All the questions re UHI, changes in land use local topographic effects etc are simply sidestepped.
4. Perhaps most importantly – what we really need to measure is the enthalpy of the system – the land measurements do not capture this aspect because the relative humidity at the time of temperature measurement is ignored. In water the temperature changes are a good measure of relative enthalpy changes.
5. It is very clear that the most direct means to short term and decadal length predictions is through the study of the interactions of the atmospheric sytems ,ocean currents and temperature regimes – PDO ,ENSO. SOI AMO AO etc etc. and the SST is a major measure of these systems.Certainly the SST data has its own problems but these are much less than those of the land data.
What does the SST data show? The 5 year moving SST temperature average shows that the warming trend peaked in 2003 and a simple regression analysis shows an eight year global SST cooling trend since then .The data shows warming from 1900 - 1940 ,cooling from 1940 to about 1975 and warming from 1975 – 2003. CO2 levels rose monotonically during this entire period.There has been no net warming since 1997 - 15 years with CO2 up 7.9% and no net warming. Anthropogenic CO2 has some effect but our knowledge of the natural drivers is still so poor that we cannot accurately estimate what the anthropogenic CO2 contribution is. Since 2003 CO2 has risen further and yet the global temperature trend is negative. This is obviously a short term on which to base predictions but all statistical analyses of particular time series must be interpreted in conjunction with other ongoing events and in the context of declining solar magnetic field strength and activity – to the extent of a possible Dalton or Maunder minimum and the negative phase of the Pacific Decadal a global 20 – 30 year cooling spell is more likely than a warming trend.
It is clear that the IPCC models , on which AL Gore based his entire anti CO2 scare campaign ,have been wrongly framed. and their predictions have failed completely.This paradigm was never well founded ,but ,in recent years, the entire basis for the Climate and Temperature trends and predictions of dangerous warming in the 2007 IPCC Ar4 Summary for Policy Makers has been destroyed. First - this Summary is inconsistent with the AR4 WG1 Science section. It should be noted that the Summary was published before the WG1 report and the editors of the Summary , incredibly ,asked the authors of the Science report to make their reports conform to the Summary rather than the other way around. When this was not done the Science section was simply ignored..
I give one egregious example - there are many others.Most of the predicted disasters are based on climate models.Even the Modelers themselves say that they do not make predictions . The models produce projections or scenarios which are no more accurate than the assumptions,algorithms and data , often of poor quality,which were put into them. In reality they are no more than expensive drafting tools to produce power point slides to illustrate the ideas and prejudices of their creators. The IPCC science section AR4 WG1 section 8.6.4 deals with the reliability of the climate models .This IPCC science section on models itself concludes:
"Moreover it is not yet clear which tests are critical for constraining the future projections,consequently a set of model metrics that might be used to narrow the range of plausible climate change feedbacks and climate sensitivity has yet to be developed"
What could be clearer. The IPCC itself says that we don't even know what metrics to put into the models to test their reliability.- i.e. we don't know what future temperatures will be and we can't yet calculate the climate sensitivity to anthropogenic CO2.This also begs a further question of what mere assumptions went into the "plausible" models to be tested anyway. Nevertheless this statement was ignored by the editors who produced the Summary. Here predictions of disaster were illegitimately given "with high confidence." in complete contradiction to several sections of the WG1 science section where uncertainties and error bars were discussed.
A key part of the AGW paradigm is that recent warming is unprecedented and can only be explained by anthropogenic CO2. This is the basic message of the iconic "hockey stick " However hundreds of published papers show that the Medieval warming period and the Roman climatic optimum were warmer than the present. The infamous "hide the decline " quote from the Climategate Emails is so important. not so much because of its effect on one graph but because it shows that the entire basis if dendrothermometry is highly suspect. A complete referenced discussion of the issues involved can be found in "The Hockey Stick Illusion - Climategate and the Corruption of science " by AW Montford.
Temperature reconstructions based on tree ring proxies are a total waste of time and money and cannot be relied on.
There is no evident empirical correlation between CO2 levels and temperature, In all cases CO2 changes follow temperature changes not vice versa.It has always been clear that the sun is the main climate driver. One new paper " Empirical Evidence for a Celestial origin of the Climate Oscillations and its implications "by Scafetta from Duke University casts new light on this. http://www.fel.duke.edu/~scafetta/pdf/scafetta-JSTP2.pdf Humidity, and natural CO2 levels are solar feedback effects not prime drivers. Recent experiments at CERN have shown the possible powerful influence of cosmic rays on clouds and climate.
Solar Cycle 24 will peak in a year or two thus masking the cooling to some extent, but from 2014 on, the cooling trend will become so obvious that the IPCC will be unable to continue ignoring the real world - even now Hansen and Trenberth are desperately seeking ad hoc fixes to locate the missing heat.