AUTHOR=Helama Samuli , Herva Hannu , Arppe Laura , Gunnarson Björn , Frank Thomas , Holopainen Jari , Nöjd Pekka , Mäkinen Harri , Mielikäinen Kari , Sutinen Raimo , Timonen Mauri , Uusitalo Joonas , Oinonen Markku 

TITLE=Disentangling the Evidence of Milankovitch Forcing From Tree-Ring and Sedimentary Records

JOURNAL=Frontiers in Earth Science

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.871641

DOI=10.3389/feart.2022.871641

ISSN=2296-6463

ABSTRACT=Tree-ring records constitute excellent high-resolution data and provide valuable information for climate science and palaeoclimatology. Tree-ring reconstructions of past temperature variations agree to show evidence for annual to centennial anomalies in past climate and place the industrial-era warming in the context of the late Holocene climate patterns and regimes. Despite their wide use in palaeoclimate research, however, tree rings have also been deemed unsuitable as low-frequency indicators of past climate. Arising debate concerns whether the millennia-long tree-ring records show the signals of orbital forcing due to the Milankovitch cycles. Here we produce a summer-temperature reconstruction from tree-ring chronology running through mid and late Holocene times (since 5486 BCE) composed of minimum blue channel light intensity (BI). The BI reconstruction correlates with existing and new tree-ring chronologies built from maximum latewood density (MXD) and, unlike the MXD data, shows temperature trends on Milankovitch scales comparable to various types of sedimentary proxy across the circumpolar Arctic. Our results demonstrate an unrevealed potential of novel, unconventional tree-ring variables to contribute to geoscience and climate research by their capability to provide