Periodic Nature of Climate

Orbital Chronology of Early Eocene Hyperthermals from the Contessa Road Section, Central Italy

Simone Galeotti, Srinath Krishnan, Mark Pagani, Luca Lanci, Alberto Gaudio, James C. Zachos, Simonetta Monechi, Guia Morelli, Lucas Lourens

High-resolution geochemical analyses of the Lower Eocene Contessa Road section (Italy) reveal orbitally controlled fluctuations in the percent concentration of calcium carbonate (wt.% CaCO3) that include the ETM2 (Elmo) and ETM3 hyperthermal events. Patterns of increased dissolution, negative carbon isotope excursions, and warmer global climates are intimately linked to maxima in insolation, through the global carbon cycle. Extraction of short- and long-eccentricity orbital periodicities of the wt.% CaCO3 record provides a relative cyclochronology for the interval ranging from ca.52 to 55.5 Ma. The Contessa Road section is easily accessible and offers a continuous integrated stratigraphic record (stable isotopes, standard calcareous plankton biostratigraphy, magnetostratigraphy, and cyclostratigraphy), thus providing a potential type succession for the study of Early Eocene hyperthermals.

Quasi-Periodic Climate Teleconnections between Northern and Southern Europe During the 17th - 20th Centuries

Stephen R. Meyers and Mark Pagani

The North Atlantic Oscillation (NAO) is the leading mode of atmospheric variability in the North Atlantic region, influencing storm tracks and creating a dipole pattern of precipitation from north to south across Western Europe. This distinct spatial distribution of precipitation provides a framework that can be potentially used to identify and reconstruct patterns of past NAO-forced climate variability. In this study we use tree-ring width series from Western Europe, in conjunction with principal components analysis and advanced spectral methods, to prospect for quasi-periodic climate signals that are forced by the NAO. We identify a robust 25 year anti-phased synchronization in climate variability between Scandinavia and the Mediterranean during the 17th-20th centuries. The amplitude of the 25 year beat displays a long-term modulation in northern and southern Europe, with minimum amplitude during the late Maunder Minimum. This amplitude minimum coincides with a maximum in Delta14C, suggesting a potential solar or oceanic influence on the intensity of the 25 year band of quasi-periodic variability.