774–775 carbon-14 spikeThe 774–775 carbon-14 spike is an observed increase of around 1.2% in the concentration of the radioactive carbon-14 isotope in tree rings dated to 774 or 775 CE, which is about 20 times higher than the normal year-to-year variation of radiocarbon in the atmosphere. It was discovered during a study of Japanese cedar tree-rings, with the year of occurrence determined through dendrochronology. A surge in beryllium isotope 10Beberyllium-10, detected in Antarctic ice cores, has also been associated with the 774–775 event.
VarveA varve is an annual layer of sediment or sedimentary rock. The word 'varve' derives from the Swedish word varv whose meanings and connotations include 'revolution', 'in layers', and 'circle'. The term first appeared as Hvarfig lera (varved clay) on the first map produced by the Geological Survey of Sweden in 1862. Initially, "varve" referred to each of the separate components comprising a single annual layer in glacial lake sediments, but at the 1910 Geological Congress, the Swedish geologist Gerard De Geer (1858–1943) proposed a new formal definition, where varve means the whole of any annual sedimentary layer.
Taxus baccataSpeciesbox | image = Taxus baccata MHNT.jpg | image_caption = Taxus baccata (European yew) shoot with mature and immature cones | status = LC | status_system = IUCN3.1 | status_ref = | genus = Taxus | species = baccata | authority = L. | range_map = Taxus baccata range.svg | range_map_caption = Natural (native [green] + naturalised [ochre]) rangeBenham, S. E., Houston Durrant, T., Caudullo, G., de Rigo, D., 2016. Taxus baccata in Europe: distribution, habitat, usage and threats.
Medieval Warm PeriodThe Medieval Warm Period (MWP), also known as the Medieval Climate Optimum or the Medieval Climatic Anomaly, was a time of warm climate in the North Atlantic region that lasted from 950 to 1250. Climate proxy records show peak warmth occurred at different times for different regions, which indicate that the MWP was not a globally uniform event. Some refer to the MWP as the Medieval Climatic Anomaly to emphasize that climatic effects other than temperature were also important.
