Twentieth-century summer warmth in northern Yakutia in a 600-year context

We report unusual twentieth-century early-summer warmth recorded by larch tree-rings at the northern tree-line in far northeastern Eurasia (Yakutia). The tree-ring series are strongly replicated and well suited to the detection of fluctuations on interannual to century timescales. They are strongly correlated with local instrumental temperature data. Mean early-summer temperature in the twentieth century significantly exceeds that of any period of the same length since AD 1400. A century-scale trend, which commences in the mid-nineteenth century, is superimposed on interannual and decadal fluctuations, for example a marked cooling since 1978. While many of the 20 coolest early summers in the reconstruction occur within a few years after major explosive volcanic eruptions from low-latitude volcanoes, several of the 20 warmest early summers followed major explosive eruptions from high-latitude volcanoes.