RealClimate was so concerned with our paper Structural break models of climatic regime-shifts that they felt compelled to post a paper by Swanson and Tsonis in response , see Warming, interrupted: Much ado about natural variability.

There are a number of similarities and differences. Firstly, ST09 uses a very different method, fitting periodic fluctuations in ocean temperature to spatially distributed data. Regime-shifts are recognized with a measure of coherence between areas, and their theory is that shifts are more likely when synchronized. With this approach, they arrive at major shifts in 1976 as we do, and in 2002, after the big 1998 El Nino.

Using a simple Chow test for structural breaks, we get a break in 1978 and also in 1997, just before the big El Nino. These dates are within bounds of error, and differences in the method, so one might as well say they are consistent.

Tsonis and Swanson previously published on the topic, and its hard to see how this paper contributed any additional work. The only change I can see is stated below:

In contrast to the definition of coupling used by Tsonis et al. [2007], a clear statistical definition of ‘strong’ and ‘weak’ coupling is possible simply by calculating the coupling using surrogate data generated from an AR-1 process with the same autocorrelation as the observed mode time series.

But the paper does not provide any data, any means of verifying their claims, anything really other than a statement of results. Very dissapointing that this should qualify as a new paper, as nothing seems to have changed, except for the order of the authors.

Another difference is that Swanson and Tsonis do not attempt to forecast temperatues (except for a figure in the RC post), only asserting that their results indicate this current regime will persist for a few decades, with probably flat temperatures. I agree, that an underlying warming could still be occurring, and would be expected to resume when this current regime ends.

However, when an estimate is made of the underlying rate of warming, assuming the temperature increase from 1976 to 1998 was based on the sum of the underlying rate, enhanced by the regime shift, as shown in our paper the underlying warming does not intersect with the current flat temperature regime until around 2050, and only increases by 0.2C by 2100.

Another difference is that while our model is created with empirical fits to data, it is backed up by reference to physical studies of changes in ocean currents, and physically based determinations of climate sensitivity to CO2 by Spencer.