Climate variability in subarctic area for the last two millennia

Abstract

Abstract. To put in perspective the recent climate change, it is necessary to extend the instrumental climate records with proxy data from palaeoclimate archives. Arctic climate variability for the last two millennia has been investigated using statistical and signal analyses from three regionally averaged records from the North Atlantic, Siberia and Alaska based on many sort of proxy data archived in the Arctic 2k database. In the North Atlantic and Alaska areas, the major climatic trend is characterized by long-term cooling interrupted by the recent warming that started at the beginning of the 19th century. This cooling trend is not clearly visible in the Siberian region. The Little Ice Age (LIA) was identified from the individual series and is characterized by an important spatial and temporal expression of climate variability. It started at the earliest by around 1200 AD and ended at the latest in the middle of the 20th century. The large spread temporal coverage of LIA did not show regional consistency or particular spatial distribution and did not show relationship with archive/proxy type either. A focus on the last two centuries shows a recent warming characterized by a well-marked warming trend paralleling with increasing greenhouse gas emissions. It also shows a multi-decadal variability likely due to natural processes acting on the internal climate system variability at regional scale. A 16–30 years cycle is found in Alaska and seems to be linked to the Pacific Decadal Oscillation (PDO) whereas ~ 20–30 and ~ 50–90 years periodicities characterize the North Atlantic climate regime, likely in relation with the Atlantic Multidecadal Oscillation (AMO). These regional features are apparently linked to the sea-ice cover fluctuations through ice-temperature positive feedback.

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

“…Here, we neither aimed to check for their further inconsistencies nor attempted to evaluate their veracity but calculated the mean temperature records for different proxy types. In keeping with the Milankovitch scale forcing, these records show varying but generally declining summer temperatures over the mid-and late-Holocene times until the first millennium BCE, after which the tree-ring and especially the diatom and chironomid data indicate a transient rise in temperatures, followed by a subsequent temperature decline toward the coolest centuries of all records, in accordance with the "Little Ice Age" climate as frequently recorded in several types of proxy evidence around the circumpolar Arctic sites (Kaufman et al, 2009;Nicolle et al, 2018;Helama et al, 2021). Clearly, different types of proxy data come with their own characteristics.…”

Spatio-temporal variability of Arctic summer temperatures over the past two millennia: an overview of the last major climate anomalies

“…In agreement with findings of Nicolle et al (2017), our results demonstrate this orbital cooling trend is not necessarily observed in all sub-regions, although Nicolle et al (2017) even exhibit a warming with a mean temperature rise of +0.5 ± 0.1…”