date: Sun, 2 Nov 2008 01:50:09 -0400 (EDT) from: g.mcgregor@auckland.ac.nz subject: JOC-08-0099 - Invitation to Review to: t.osborn@uea.ac.uk 02-Nov-2008 TIM: COULD YOU HELP OUT WITH A QUICK REVIEW OF THIS. I HAVE PASTED BELOW THE COMMENTS FROM THE OTHER REVIEWER FYI Dear Dr Osborn Manuscript # JOC-08-0099 entitled "1963: The break point of the Northern Hemisphere temperature trend during the twentieth century" by Ivanov, Martin; Evtimov, Stilian has been submitted to the International Journal of Climatology. The abstract and author details are to be found at the foot of this email. As you are an acknowledged expert in this area, I am writing to see if you could find time to review this manuscript. Ideally I would like the review back to me within 3 weeks if possible. Please let me know within 7 days if you will be able to review this paper. If you are unable to review would you take a moment to please recommend one or two other possible referees with expertise in this area. You can respond to this invitation by either emailing me directly, or if you are willing to review the paper you may use the shortcut of clicking on the "Agree" link below. This will initiate another email that grants you access to the manuscript. To respond automatically, click below: Agreed: http://mc.manuscriptcentral.com/joc?URL_MASK=Q2CScyY6sCfdBhJSX62J You will then have access to the manuscript and reviewer instructions in your Referee Centre. Thank you for taking the time to consider this request. Sincerely, Prof. Glenn McGregor International Journal of Climatology MANUSCRIPT DETAILS TITLE: 1963: The break point of the Northern Hemisphere temperature trend during the twentieth century AUTHORS: Ivanov, Martin; Evtimov, Stilian ABSTRACT: Climate changes gradually and abruptly. The Northern Hemisphere temperature series bears the fingerprint of these changes. Using rigorous statistical tools we show that during the twentieth century this series is well described by a stationary noise process around a one-time broken linear trend. We detect 1963 as the year of the break and identify it with the time of an abrupt climate shift. We offer a scenario for the latter. The concurrence of the major rhythms of internal climate variability and the Mount Agung eruption give rise to a critical fluctuation. The climate system cannot bear this fluctuation without consequences and abruptly moves to a new state. In the new regime the rate of temperature growth almost triples. ===================== OTHER REVIEWER'S COMMENTS Review of E963: The break point of the Northern Hemisphere temperature trend during the twentieth centuryEby Martin Ivanov and Stilian Evtimov (manuscript #JOC-08-0099). The authors analyze global temperatures since 1890 until the present and its linear trend. They argue there was one break in the trend caused by a climate shift around 1963-1964 caused by the eruption of Mt. Agung and the simultaneous reversal in polarity of three major teleconnection indices:, the NAO, the PNA and the SOI. I applaud the authorsEefforts to employ statistical techniques not commonly used in meteorology to analyze meteorological time series. The authors use a test derived from economics to identify any breaks or abrupt shifts in the global temperature time series. The validity of the entire manuscript rests on the robustness of this test to accurately identify an irreversible break in the trend line. Unfortunately I have to admit that I am neither familiar with the technique nor am I qualified to judge the merit of the results, still here are some of my concerns. The time series contains many large and abrupt temperature swings that at least by eye are as large as the 1963-1964 temperature shift including the early 1900s, and all of the decades from the 1940s through the 1970s. The authors do mention the better-known 1970s climate shift but I feel that the authors could do more to prove the singularity of the 1963 climate shift in the twentieth century. If indeed their technique contradicts the idea of the 1970s climate shift this is important and the authors need to spend more time explaining and justifying this result. The authors are stingy with tables and figures. I really could not appreciate the information provided in Table 1, the authors need to break up Table 1 into multiple tables and provide more information to make the data useful to the reader. I would also suggest including more figures. One additional figure could be the times series of the land and ocean temperatures separately with the same trend analysis as with the combined global temperature time series of Figure 1. Also, since the authors are suggesting a change in polarity of the NAO, PNA and ENSO indices to explain the break in the trend of the global temperature time series, it would be useful to regress all of the teleconnection time series with the temperature time series and then try to reconstruct the observed temperature time series. This way the authors can also quantify how much of the observed cooling in 1963 can be attributed to the individual teleconnection indices rather than just hand waving. Better yet would be to use a GCM and sample the model for periods where the teleconenction indices match the polarity changes observed in 1963 and measure the temperature change in the model. I dont expect the authors to do this but maybe they can devise some Monte Carlo simulations as a poor mans GCM using the observed time series to test their hypothesis. Finally I strongly feel that the authors should remove the last paragraph of the Discussion section. Extrapolating from their results to human climate control is a huge leap and I feel that it is not justified nor useful to the manuscript.