International Journal of Statistics and Applications
p-ISSN: 2168-5193 e-ISSN: 2168-5215
2024; 14(1): 1-6
doi:10.5923/j.statistics.20241401.01
Received: Dec. 22, 2023; Accepted: Jan. 7, 2024; Published: Jan. 10, 2024
Erhard Reschenhofer
Retired from University of Vienna, Austria
Correspondence to: Erhard Reschenhofer, Retired from University of Vienna, Austria.
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Copyright © 2024 The Author(s). Published by Scientific & Academic Publishing.
This work is licensed under the Creative Commons Attribution International License (CC BY).
http://creativecommons.org/licenses/by/4.0/
Estimates of the autocorrelation in monthly temperature series are obtained in two steps. Firstly, a proper seasonal-adjustment method is applied which also works in the case of a time-varying seasonal pattern. Secondly, the seasonally adjusted series are subjected to a simple graphical procedure which enables the immediate and unbiased assessment of the magnitude of the first-order autocorrelation. The highest values occur in the northern part of the subpolar gyre. The autocorrelation there rises in the early 1940s from around 0.7 to around 0.8 and finally in the late 1990s to just under 0.9. The changes happen abruptly rather than steadily. There are no indications of a further rise beyond 0.9 towards 1, which some researchers would interpret as a sign of an imminent collapse of the Atlantic Meridional Overturning Circulation. On the contrary, there are indications that global warming is finally catching up with this region too. The consequence of this development would be that the rising trend will mask the Atlantic Multidecadal Oscillation, which contributes significantly to the autocorrelation, and thereby cause even a drop in the autocorrelation. Overall, the results are ambivalent. On the one hand, the new methods allow for more precise and up-to-date tracking of early-warning signs. On the other hand, the empirical evidence points to structural breaks and identification problems that make it impossible at this point in time to determine whether and when the system will collapse.
Keywords: Seasonal adjustment, Detrending, AMOC collapse, Early-warning signs, Autocorrelation
Cite this paper: Erhard Reschenhofer, Coping with Seasonal Effects of Global Warming in the Estimation of Second Moments, International Journal of Statistics and Applications, Vol. 14 No. 1, 2024, pp. 1-6. doi: 10.5923/j.statistics.20241401.01.
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