Related by context. Frequent words. (Click for all words.) 69 mass extinction 67 mass extinctions 64 glaciation 63 volcanism 61 megafauna 60 Little Ice Age 58 supernova explosion 57 greenhouse warming 56 Ordovician 56 Late Cretaceous 55 Quaternary 55 extinctions 54 atmospheric carbon dioxide 54 Pleistocene 53 PETM 53 supernova explosions 53 Pliocene 53 Precambrian 53 Medieval Warm Period 53 anoxic 52 hydrothermal vents 52 species extinctions 52 icecap 52 plate tectonics 52 CO2 concentrations 52 coral bleaching 52 hydrothermal 52 Tunguska 51 amphibian species 51 El Ninos 51 Cretaceous 51 sedimentary rock 51 seismicity 51 gamma ray burst 51 atmospheric CO2 51 mid latitudes 51 Nature Geoscience 51 archaea 50 dinosaurs 50 tetrapods 50 Mesozoic 50 X ray emission 50 continental drift 50 sunspot activity 50 greenhouse gas concentrations 50 biosphere 50 Holocene 50 hominids 50 volcanic eruptions 50 permafrost 50 substorms 50 vertebrate species 50 volcanic activity 50 anthropogenic climate 49 atmospheric circulation 49 oxygen depletion 49 single celled organisms 49 mammoths 49 magnetar 49 Ice Age 49 ozone depletion 49 diatoms 49 geologically active 49 glacial melt 49 anthropogenic 49 ejecta 49 Oetzi 49 geologic 49 Ocean acidification 49 NSIDC 48 mountain glaciers 48 polar caps 48 volcanic gases 48 crustal 48 Deepwater Horizon blowout 48 woolly mammoths 48 journal Geology 48 nitrogen fixation 48 magmatic 48 fossil 48 dinosaurs roamed 48 methane concentrations 48 GRBs 48 multicellular 48 plesiosaur 48 Wilkins Ice Shelf 48 atmospheric concentrations 48 melting permafrost 48 Eocene 48 olivine 48 sediment cores 47 biodiversity hotspots 47 abundances 47 ocean acidification 47 Eta Carinae 47 Greenland glaciers 47 Australopithecus afarensis 47 Homo sapiens 47 cometary 47 outgassing 47 hominid