Testing long-term summer temperature reconstruction based on maximum density chronologies obtained by reanalysis of tree-ring data sets from northernmost Sweden and Finland

Here we analyse the maximum latewood density (MXD) chronologies of two published tree-ring data sets: one from Torneträsk region in northernmost Sweden (TORN; Melvin et al., 2013) and one from northern Fennoscandia (FENN; Esper et al., 2012). We paid particular attention to the MXD low-frequency variations to reconstruct summer (June–August, JJA) long-term temperature history. We used published methods of tree-ring standardization: regional curve standardization (RCS) combined with signal-free implementation. Comparisons with RCS chronologies produced using single and multiple (non-climatic) ageing curves (to be removed from the initial MXD series) were also carried out. We develop a novel method of standardization, the correction implementation of signal-free standardization, tailored for detection of pure low-frequency signal in tree-ring chronologies. In this method, the error in RCS chronology with signal-free implementation is analytically assessed and extracted to produce an advanced chronology. The importance of correction becomes obvious at lower frequencies as smoothed chronologies become progressively more correlative with correction implementation. Subsampling the FENN data to mimic the lower chronology sample size of TORN data shows that the chronologies bifurcate during the 7th, 9th, 17th and 20th centuries. We used the two MXD data sets to reconstruct summer temperature variations over the period 8 BC through AD 2010. Our new reconstruction shows multi-decadal to multi-centennial variability with changes in the amplitude of the summer temperature of 2.2 °C on average during the Common Era. Although the MXD data provide palaeoclimate research with a highly reliable summer temperature proxy, the bifurcating dendroclimatic signals identified in the two data sets imply that future research should aim at a more advanced understanding of MXD data on distinct issues: (1) influence of past population density variations on MXD production, (2) potential biases when calibrating differently produced MXD data to produce one proxy record, (3) influence of the biological age of MXD data when introducing young trees into the chronology over the most recent past and (4) possible role of waterlogging in MXD production when analysing tree-ring data of riparian trees

Suicide mortality in European countries and Post-Soviet states since 1955: Illustrating the longtime trends and patterns of recent changes

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An 854-year tree-ring chronology of Scots pine for south-west Finland

A near-mil len nial tree-ring chro nol ogy (AD 1147–2000) is pre sented for south-west Fin land and an a lyzed us ing dendroclimatic meth ods. This is a com pos ite chro nol ogy com pris ing sam ples both from stand ing pine trees (Pinus sylvestris L.) and subfossil trunks as re cov ered from the lake sed i ments, with a to tal sam ple size of 189 tree-ring sample se ries. The se ries were dendrochronologically cross-dated to ex act cal en dar years to por tray vari abil ity in tree-ring widths on inter-an nual and lon ger scales. Al though the stud ied chro nol ogy cor re lates sta tis ti cally sig nif i cantly with other long tree-ring width chro nol o gies from Fin land over their com mon pe riod (AD 1520–1993), the south-west chro nol ogy did not ex hibit sim i larly strong mid-sum mer tem per a ture or spring/early-sum mer pre cip i ta tion sig nals in com par i son to pub lished chro nol o gies. On the other hand, the south-west chro nol ogy showed high est cor re la tions to the North At lan tic Os cil la tion in di ces in win ter/spring months, this as so ci a tion fol low ing a dendroclimatic fea ture com mon to pine chro nol o gies over the re gion and ad ja cent ar eas. Paleoclimatic com par i son showed that tree-rings had var ied sim i larly to cen tral Eu ro pean spring tem per a tures. It is pos tu lated that the col lected and dated tree-ring ma te rial could be stud ied for wood sur face reflectance (blue chan nel light in ten sity) and sta ble iso topes, which both have re - cently shown to cor re late notably well with sum mer tem per a tures

The 4.2 ka event: A review of palaeoclimate literature and directions for future research

In recent years, much evidence has been presented on the 4.2 ka event. A review of 317 palaeoclimate papers shows that dry conditions were common during the event, especially from Eastern Mediterranean to India. The 4.2 ka event was not, however, a global drought event. Wet conditions were reported especially for central/northern Europe and sub-Saharan Africa. The 4.2 ka event is typically characterized either as short (4.2–4.0 ka) or long (4.4–3.8 ka) episode, possibly developing over an extended interval of time, in keeping with the North Atlantic forcing and correlating with the Bond 3 event of ice-rafted debris. This forcing is understood to drive a southward migration of the Inter-Tropical Convergence Zone (ITCZ), resulting in decreased rainfall over most of the Asian monsoon region, with possibility that an interplay of El Niño–Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) has modulated the global circulation. Cold conditions were also reported but less frequently, in comparison to other Bond events such as the 8.2 ka event, Dark Ages Cold Period and Little Ice Age. Some high-resolution records show a double peak structure of which two anomalies are tree-ring dated to 4.14–4.05 ka and 3.97 ka. Accurately and precisely dated high-resolution records indicative of various climatic variables, especially outside of the traditional study region (Mediterranean–Middle East–India–China), including reconstructions of the ENSO and NAO histories and ITCZ migrations, are crucially needed for rigorous examination of the global scale characteristics of the 4.2 ka event and its forcings. Such research seems to be just beginning

Nonoverlapping Magisteria Versus Science-Religion Integration: Rereading Stephen Jay Gould

The principle of nonoverlapping magisteria (NOMA), by Stephen Jay Gould, is commonly cited in the science-religion literature as an archetype of a model separating the domains of science and religion. As such, NOMA represents the independence category in Ian Barbour’s science-religion typology. However, it is commonly neglected that NOMA also permits dialogue and even integration of scientific and religious inputs at the personal level, i.e. beyond the level of magisteria. To distinguish the two levels, it is essential to note that Gould considered the magisteria not as any kind of domain but closely related to teaching authorities