1IPGP - Institut de Physique du Globe de Paris (IPGP, 1 rue Jussieu, 75238 Paris cedex 05 ; Université Paris Diderot, Bât. Lamarck A case postale 7011, 75205 Paris CEDEX 13 - France)
Abstract : We investigate global temperature data produced by the Climate Research Unit at the University of East Anglia (CRU) and the Berkeley Earth Surface Temperature consortium (BEST). We first fit the 1850-2010 data with polynomials of degrees 1 to 9. A significant ~60-yr oscillation is accounted for as soon as degree 4 is reached. This oscillation is even better modeled as a broken line, more precisely a series of ~30-yr long linear segments, with slope breaks (singularities) in ~1904, ~1940, and ~1974 (±3 yr), and a possible recent occurrence at the turn of the 20th century. Oceanic indices PDO (Pacific Decadal Oscillation) and AMO (Atlantic Multidecadal Oscillation) have undergone major changes (re- spectively of sign and slope) roughly at the same times as the temperature slope breaks. This can be interpreted with a system of oceanic non-linear coupled oscillators with abrupt mode shifts. Thus, the Earth's climate may have entered a new mode (a new ~30-yr episode) near the turn of the 20th century: no further temperature increase, a dominantly nega- tive PDO index and a decreasing AMO index might be expected for the next decade or two.
https://hal-insu.archives-ouvertes.fr/insu-00944085
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Submitted on : Friday, August 7, 2020 - 8:08:41 AM Last modification on : Thursday, December 10, 2020 - 10:52:06 AM Long-term archiving on: : Monday, November 30, 2020 - 4:10:14 PM
Vincent Courtillot, Jean-Louis Le Mouel, Vladimir Kossobokov, Dominique Gibert, Fernando Lopes. Multi-Decadal Trends of Global Surface Temperature: A Broken Line with Alternating ~30 yr Linear Segments?. Atmospheric and Climate Sciences, Scientific Research Publishing, 2013, 3, pp.364-371. ⟨10.4236/acs.2013.33038⟩. ⟨insu-00944085⟩