Related by context. Frequent words. (Click for all words.) 62 Younger Dryas 60 interglacial period 57 interglacial 57 Holocene 56 Medieval Warm Period 55 epoch 55 Little Ice Age 53 hydrological cycle 52 glaciation 52 atmospheric methane 52 atmospheric CO 51 greenhouse warming 51 mass extinction 51 Pliocene 51 mass extinctions 50 Cretaceous Period 49 biosphere 49 supercontinent 49 atmospheric CO2 49 volcanism 49 Pleistocene 48 terrestrial ecosystems 48 Homo Sapiens 48 anthropogenic climate 48 marine sediments 48 solar nebula 47 decadal 47 megafauna 47 ENSO 46 radiative forcing 46 prehistory 46 geologic 46 epochs 46 species extinctions 46 Paleocene 46 atmospheric carbon dioxide 46 sunspot cycle 46 Gliese #g 46 Kuiper belt 46 Quaternary 46 lake sediments 46 methane hydrates 45 anthropogenic 45 Tiktaalik 45 greenhouse gas concentrations 45 multicellular organisms 45 aridity 45 continental drift 45 equatorial Pacific Ocean 45 Research NBER 45 Precambrian 45 genus Homo 45 biodiversity hotspots 45 glacial melting 45 multicellular 45 Homo sapiens 45 climatological 44 millennium 44 sunspot activity 44 extinctions 44 glacial melt 44 atmospheric concentrations 44 Late Cretaceous 44 landmasses 44 El Ninos 44 diatoms 44 Industrial Revolution 44 #.#C [004] 44 methane hydrate 43 earths 43 Mayan civilization 43 cataclysm 43 Ice Age 43 storminess 43 planetary nebula 43 Ocean acidification 43 climate alarmists 43 biogenic 43 El Nino warming 43 El Niño 43 galaxy formation 43 crustal 43 atmospheric circulation 43 sunspot 43 PETM 43 climatic 43 millennia 43 continental crust 43 oxygen isotopes 43 retreating glaciers 43 planetary 43 planet 43 ecological degradation 43 millenniums 43 plate tectonics 42 icecap 42 supernova explosion 42 civilization 42 dinosaurs roamed 42 Fertile Crescent 42 Carboniferous