Radiocarbon dating methods typically assume that there are no significant tropospheric (14)CO(2) gradients within the low- to mid-latitude zone of the Northern Hemisphere. Comparison of tree ring (14)C data from southern Germany and Anatolia supports this assumption in general but also documents episodes of significant short-term regional (14)CO(2) offsets. We suggest that the offset is caused by an enhanced seasonal (14)CO(2) cycle, with seasonally peaked flux of stratospheric (14)C into the troposphere during periods of low solar magnetic activity, coinciding with substantial atmospheric cooling. Short-term episodes of regional (14)CO(2) offsets are important to palaeoclimate studies and to high-resolution archaeological dating.

May–June precipitation is the primary limiting factor in annual tree‐ring growth of the oaks of northeastern Greece and northwestern Turkey (39–42°N, 22–37°E). In a regional tree‐ring chronology of historic building and modern forest samples, the May–June precipitation explains at least 40% of the variance for 1900–1985, and is reconstructed here from A.D. 1089–1989. The reconstruction is compared to three other precipitation reconstructions for Turkey. The mean temperature of May and June is also a growth‐limiting factor owing to its effect on the availability of precipitation to the trees, but is more difficult to calibrate and reconstruct accurately owing to the trees' indirect response and the low number of long‐temperature records available for the interior of northwestern Turkey.An analysis of the various methods of manipulating oak tree‐ring data for regional climate reconstruction shows that removing all but the high‐frequency variability plus normalizing the oak data sets before combining them into a master chronology are optimal techniques for a reasonable precipitation reconstruction of the entire area over the instrumental period. However, these methods do remove the low‐frequency signal and dampen some of the evidence of local extremes in May–June precipitation; these issues are discussed here and will be addressed in future research. Copyright © 2007 Royal Meteorological Society

We report an extensive program of high-precision radiocarbon dating to establish the best date for a floating 1599-year Anatolian tree ring chronology that spans the later third millennium B.C. through the earlier first millennium B.C. This chronology is directly associated with a number of key sites and ancient personages. A previously suggested dating is withdrawn and is replaced by a robust new date fix 22 (+4 or -7) years earlier. These new radiocarbon wiggle-matched dates offer a unique independent resource for establishing the precise chronology of the ancient Near East and Aegean and help resolve, among others, a long-standing debate in favor of the so-called Middle Mesopotamian chronology.

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Calendar-dated tree-ring sequences offer an unparalleled resource for high-resolution paleoenvironmental reconstruction. Where such records exist for a few limited geographic regions over the last 8,000 to 12,000 years, they have proved invaluable for creating precise and accurate timelines for past human and environmental interactions. To expand such records across new geographic territory or extend data for certain regions further backward in time, new applications must be developed to secure “floating” (not yet absolutely dated) tree-ring sequences, which cannot be assigned single-calendar year dates by standard dendrochronological techniques. This study develops two approaches to this problem for a critical floating tree-ring chronology from the East Mediterranean Bronze–Iron Age. The chronology is more closely fixed in time using annually resolved patterns of 14C, modulated by cosmic radiation, between 1700 and 1480 BC. This placement is then tested using an anticorrelation between calendar-dated tree-ring growth responses to climatically effective volcanism in North American bristlecone pine and the Mediterranean trees. Examination of the newly dated Mediterranean tree-ring sequence between 1630 and 1500 BC using X-ray fluorescence revealed an unusual calcium anomaly around 1560 BC. While requiring further replication and analysis, this anomaly merits exploration as a potential marker for the eruption of Thera.