North Atlantic-Fennoscandian Holocene climate trends and mechanisms. (1st September 2016)

• Record Type: Journal Article
• Authors: Sejrup, Hans Petter; Seppä, Heikki; McKay, Nicholas P.; Kaufman, Darrell S.; Geirsdóttir, Áslaug; de Vernal, Anne; Renssen, Hans; Husum, Katrine; Jennings, Anne; Andrews, John T.
• Is Part Of: Quaternary science reviews. Volume 147(2016)
• Page Start: 365
• Page End: 378
• Publication Date: 2016-09-01
• Subjects: Holocene -- climate -- North Atlantic -- Fennoscandia; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2016.06.005
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: To investigate the mechanisms behind Holocene regional climate trends from north of 58°N in the North Atlantic-Fennoscandian region Principal Component Analysis (PCA) was performed and a temperature anomaly stack produced from 81 proxy derived summer temperature time series from 74 sites. The PC results show distinctly different trends for near-surface versus surface temperatures, demonstrating the importance of handling these separately. The first PC of weighted sea surface summer temperature time series and continental time series explains 45 ± 8% of the variance, where the uncertainty is the standard deviation of the distribution of variance explained across the 1000 age-uncertain ensemble members. PC1 has a relatively uniform expression over the whole region, closely following the summer insolation at 65°N. The second PC explains 22 ± 4% of the variance and shows a non-uniform expression, with loadings in opposite directions in the northern and southeastern parts of the region. Comparing the PC time series with model runs and with the timing of the demise of the Laurentide Ice Sheet (LIS), suggest that this pattern reflects both topographic and albedo effects of the LIS as well as release of meltwater into the North Atlantic and Arctic Oceans. Comparing the stack of gridded records with published global stacks reveals an unusual Holocene temperature development in the North Atlantic-Fennoscandian region most likely resulting from the location relative to the decaying LIS. Highlights: Analyses of a diverse range of marine and terrestrial Holocene proxy temperature records from the North Atlantic — Fennoscandian region show: The dominant pattern of temperature fluctuations (PC1 = 45 ± 8% of the variance) during the past 10 ka is strongly uniform, likely a response summer insolation. The secondary pattern (PC2 = 22 ± 4%) shows early warming in the north and west and later warming in the southeast. The geographical expression of PC2 and climate model results indicate the influence of the disintegrating Laurentide Ice Sheet during the early Holocene