There is a new paper on the arXiv which propose an alternative view of global climate change called The Shift Hypothesis. The paper is called Emperical evidence for a double step climate change in twentieth century by Belolipetsky, Bartsev, Degermendzhi, Huang-Hsiung & Varotsos. I should say, firstly, that I applaud the authors (Belolipetsky et al.) for submitting a paper for peer-review (I’m assuming they have as the WUWT post describes it as a “submitted paper”). I should also acknowledge that I haven’t read the paper in full, so I’m happy to be corrected if my interpretation is incorrect or missing something fundamental.
I was going to make two quick comments about this paper. The first line of the introduction says
The principal indicator of global warming is, by definition, the global mean temperature.
In my (scientific) opinion, this statement is incorrect and illustrates one of the major issues in the global warming/climate change debate. Global warming is, very simply, an energy imbalance in which the Earth receives more energy from the Sun than it loses back into space. If all this energy did was heat the atmosphere and surface, then the above statement would be correct. However, it clearly does not. It also goes into the oceans and melts polar ice. To state that global warming is “by definition” an increase in global mean temperatures indicates – to me – that these authors, unfortunately, do not understand the basics of global warming.
The other comment I was going to make is that this paper appears to be a set of linear regression fits to temperature anomaly data. The conclusion seems to be (as also suggested by Bob Tisdale) that increases in the global mean temperature are driven by ENSO/PDO shifts (i.e., oscillations in the pacific ocean that bring energy from within the ocean to the surface where it can heat the surface). This is fine, but it doesn’t really tell you anything other than the steps in the temperature anomaly data are driven by ENSO/PDOs. The problem I have (as I’ve mentioned before) is that if there is no net global warming how can a series of oscillations result in a long-term warming trend? Furthermore, how can the ocean heat content be increasing if it is ocean heat (that is not being replenished through global warming) that is heating the surface? Basically, this result (and that suggested by Bob Tisdale) could be entirely consistent with standard global warming ideas. Measurements suggest that something like 90% of the excess energy associated with global warming goes into the oceans. Since ENSO/PDOs act to bring energy to the surface, then these oscillations could well be a dominant factor in providing the excess energy that heats the surface.
This paper also seems to illustrate another common idea presented by skeptics; that models are bad (because they don’t produce real data) and that you can only derive conclusions about climate change/global warming by looking at “real” data. Sure, “real” data is important but simply fitting a line or curve to a data set without attempting to understand the underlying physics or chemistry that is responsible for the changes in whatever is being measured means that you really haven’t learned anything (or at least, you have no idea about what is driving the observed changes in the quantity that is being measured). You still need models/theories to understand what you “see” when you analyse your data. Without models/theories, you’re just guessing.