Siberian Trap volcanism, global warming and the Permian Triassic mass extinction: New insights from Armenian Permian-Triassic sections: Reply

Horacek et al. (2021) commented on our publication arguing that we used an incorrect biochronology to define the Permian-Triassic (PT) boundary and that this inaccurate definition resulted in an erroneous interpretation of the oxygen isotope record in the studied Chanakhchi (former Sovestashen) section. Their comment gives us the opportunity to discuss in depth the identification of the PT boundary and to address some of the flawed arguments of Horacek et al.

Oxygen Isotopes in Tree Rings from Greenland: A New Proxy of NAO

We present the first Greenlandic tree ring oxygen isotope record (δ18OGTR), derived from four birch trees collected from the Qinguadalen Valley in southwestern Greenland in 1999. Our δ18O record spans from 1950–1999 and is significantly and positively correlated with winter ice core δ18O from southern Greenland. δ18OGTR records are positively correlated with southwestern Greenland January–August mean temperatures. North Atlantic Oscillation (NAO) reconstructions have been developed from a variety of proxies, but never with Greenlandic tree rings, and our δ18OGTR record is significantly correlated with NAO (r = −0.64), and spatial correlations with sea-level pressure indicate a classic NAO pressure seesaw pattern. These results may facilitate a longer NAO reconstruction based on long time series of tree ring δ18O records from Greenland, provided that subfossil wood can be found in areas vacated by melting glaciers.