Guest Post By Hiroshi L. Tanaka On The New Paper “Data Analysis Of Recent Warming Pattern In The Arctic” By Ohashi And Tanaka

Guest post by Hiroshi L. Tanaka of the University of the University of Tsukuba in Japan [his webpage is

Guest Post

Dr. Kiminori Itoh suggested I contact you to explain our recent work on misleading global warming predictions in reference to the comprehensive study on the Arctic Oscillation [AO]. As you have 
experienced, the winter of 2009/2010 reminded us of the global cool weather rather than global warming. The occurrence of the extreme AO minus (3 sigma) provided us additional evidence that the AO controls a large fraction of global warming.

We have a paper that was published on 13 March 2010 with my student Mr. Ohashi in SOLA:

Masahiro Ohashi and H. L. Tanaka, 2010: Vol. 6A (2010) : Data Analysis of Recent Warming Pattern in the Arctic. Special Edition -Special Edition of the Fourth Japan China Korea Joint Conference on Meteorology- p.1-4

The abstract reads

“In this study, we investigate the mechanism of the arctic warming pattern in surface air temperature (SAT) and sea ice concentrations over the last two decades in comparison with global warming since the 1970s.

According to the analysis result, it is found that the patterns of SAT and sea ice before 1989 are mostly determined by the Arctic Oscillation (AO) in winter. In contrast, arctic warming patterns after 1989 are characterized by the intensification of the Beaufort High and the reduced sea-ice concentrations in summer induced by the positive ice-albedo feedback.

It is concluded that the arctic warming before 1989 especially in winter was explained by the positive trend of the AOI. Moreover the intensified Beaufort High and the drastic decrease of the sea ice concentrations in September after 1989 were associated with the recent negative trend of the AOI. Since the decadal variation of the AO is recognized as the natural variability of the global atmosphere, it is shown that both of decadal variabilities before and after 1989 in the Arctic can be mostly explained by the natural variability of the AO not by the external response due to the human activity.”

Professor Tanaka summarized the significance of their papers for us in the following:

The main conclusions are:

(1)  The most dominant trend in observation for 1950-1999 shows  an AO pattern (natural variability), while the most dominant trend in the IPCC models shows an ice-albedo feedback pattern (anthropogenic forcing).

(2)  In the observations, the AO pattern appears as the EOF-1. However, in the IPCC 10 model mean, the ice-albedo pattern appears as EOF-1 (which is not seen in the observation), and the AO pattern appears as EOF-2.

(3)  In the EOF analysis, the ratio of variance for the ice-albedo and AO patterns are 5:2. Since the AO is a realization of a stochastic process, the variance of the AO pattern in the observations dominates the ice-albedo pattern (5:20 in theory).

(4)  Multi-decadal trends of surface air temperatures [SAT] indicates that the AO  was negative for 1950-1969, the AO was positive for 1969-1989, and the AO was negative for 1989-2008 (2010 is the extreme value). Those are realized as the natural variability superimposed on the general trend of global warming.


According to our result, the rapid warming during 1970-1990 contains a large fraction of unpredictable natural variability due to the AO. The subsequent period of 1990-2010 indicates a clear trend of the AO to be negative. The global warming has been stopped by natural variability superimposed on the gentle anthropogenic global warming. The important point is that the IPCC models have been tuned perfectly to fit the rapid warming during 1970-1990 by means of the ice-albedo feedback (anthropogenic forcing) which is not actually observed. IPCC models are justified with this wrong scientific basis and are applied to project the future global warming for 100 years in the future. Hence, we warn that the IPCC models overestimate the warming trend due to the mislead Arctic Oscillation.

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