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January 2018 : Living through a future winter

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January 2018 was a month of extremes. Not only was it by far the warmest January on record across the Western Alps, but also one of the wettest in systematic weather measurements, with widespread landslides at low elevations and massive snowfall in mountains. The weather of January 2018 was unusual, freakish in fact, at the upper extreme of the historical distribution of storminess, temperatures and precipitation in the Western Alps – breaking many weather records. Not only was January 2018 unprecedentedly warm, but also was it extremely wet and with unusual snowfall at higher elevations. As Regional Climate Models do […]

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Warming increases risk of snow avalanches in the western Himalayas

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Indian Himalaya

Often called the Third Pole, the Hindukush-Karakoram-Himalaya region, comprising the Tibetan plateau and the surrounding mountains, is the most glaciated place on Earth outside the North and South Poles. Its cryosphere is extremely susceptible—and the surrounding communities and ecosystems vulnerable—to the effects of climate change. Juan Ballesteros-Cánovas and colleagues at the University of Geneva have used tree-ring data to reconstruct more than 150 years of snow avalanches on a typical western Himalayan mountainside in northern India. Tree rings record damage, evidence of tilting, and abrupt changes in growth rate. As a result, they provide a spatially and temporally accurate history […]

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A Violent Volcanic Eruption Immortalized in Medieval Poem May Have Spurred Iceland’s Adoption of Christianity

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Memories of the largest lava flood in the history of Iceland, recorded in an apocalyptic medieval poem, were used to drive the island’s conversion to Christianity, new research suggests. A team of scientists and medieval historians, led by the University of Cambridge, has used information contained within ice cores and tree rings to accurately date a massive volcanic eruption, which took place soon after the island was first settled. Having dated the eruption, the researchers found that Iceland’s most celebrated medieval poem, which describes the end of the pagan gods and the coming of a new, singular god, describes the […]

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Multi-proxy dating the ‘Millennium Eruption’ of Changbaishan to late 946 CE

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Ranking among the largest volcanic eruptions of the Common Era (CE), the ‘Millennium Eruption’ of Changbaishan produced a widely-dispersed tephra layer (known as the B-Tm ash), which represents an important tie point for palaeoenvironmental studies in East Asia. Hitherto, there has been no consensus on its age, with estimates spanning at least the tenth century CE. Here, we identify the cosmogenic radiocarbon signal of 775 CE in a subfossil larch engulfed and killed by pyroclastic currents emplaced during the initial rhyolitic phase of the explosive eruption. Combined with glaciochemical evidence from Greenland, this enables us to date the eruption to […]

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Volcanology : Chronicling a medieval eruption

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Annales_Spirenses

The eruption of Samalas in Indonesia in 1257 ranks among the largest sulfur-rich eruptions of the Common Era with sulfur deposition in ice cores reaching twice the volume of the Tambora eruption in 1815. Sedimentological analyses of deposits confirm the exceptional size of the event, which had both an eruption magnitude and a volcanic explosivity index of 7. During the Samalas eruption, more than 40 km3 of dense magma was expelled and the eruption column is estimated to have reached altitudes of 43 km. However, the climatic response to the Samalas event is debated since climate model simulations generally predict a stronger […]