Will a New Little Ice Age Begin in the Next Few Decades?

Ogurtsov, M. G.; Lindholm, Markus; Jalkanen, Risto

doi:10.5539/apr.v5n3p70

Cited by 2 publications

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References 29 publications

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“…Several individual Fennoscandian tree growth-based proxies have indicated prominent spectral features at about 23, 30, and 90 years, 23-33 years, and 30.8-31.8 and 80.3-87.7 years in Finland [11,25,56] as well as relatively time-stable peaks at 32-33 years and at ∼55-100 years in Sweden [10]. In an analysis of seven northern hemisphere temperature reconstructions (including, e.g., [15,[57][58][59]) Ogurtsov et al [60] reported that they have an unambiguous 60-80-year multidecadal variability in common (AD 1000-1930), which is close to the range of a 67-year cycle indicated by our data. The 4Spline reconstruction without the more or less discrepant secular characteristics (see [17]) clearly records a bimodal structure-c.a.…”

Section: Discussionmentioning

confidence: 99%

Six Temperature Proxies of Scots Pine from the Interior of Northern Fennoscandia Combined in Three Frequency Ranges

Lindholm¹,

Ogurtsov

Jalkanen³

et al. 2014

Journal of Climatology

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Six chronologies based on the growth of Scots pine from the inland of northern Fennoscandia were built to separately enhance low, medium, and higher frequencies in growth variability in 1000-2002. Several periodicities of growth were found in common in these data. Five of the low-frequency series have a significant oscillatory mode at 200-250 years of cycle length. Most series also have strong multidecadal scale variability and significant peaks at 33, 67, or 83-125 years. Reconstruction models for mean July and June-August as well as three longer period temperatures were built and compared using stringent verification statistics. We describe main differences in model performance ( 2 = 0.53-0.62) between individual proxies as well as their various averages depending on provenance and proxy type, length of target period, and frequency range. A separate medium-frequency chronology (a proxy for June-August temperatures) is presented, which is closely similar in amplitude and duration to the last two cycles of the Atlantic multidecadal oscillation (AMO). The good synchrony between these two series is only hampered by a 10-year difference in timing. Recognizing a strong medium-frequency component in Fennoscandian climate proxies helps to explain part of the uncertainties in their 20th century trends.

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