Related by context. Frequent words. (Click for all words.) 59 interglacial 55 terrestrial ecosystems 52 CO2 concentrations 52 glaciation 52 atmospheric CO2 51 Little Ice Age 51 biosphere 50 atmospheric carbon dioxide 49 Pleistocene 49 atmospheric CO 49 diatom 49 diatoms 48 glacial 48 mammoths 48 marine sediments 48 ocean acidity 48 Holocene 48 icecaps 47 hydrological cycle 47 megafauna 47 greenhouse warming 47 Late Cretaceous 47 mass extinctions 46 dinosaurs 46 lithosphere 46 anthropogenic 46 vertebrate species 46 Quaternary 46 Pliocene 46 sunspot activity 46 extinctions 46 mass extinction 46 radioactive decay 45 decadal 45 Arctic tundra 45 temperate zones 45 trilobites 45 radiocarbon 45 multicellular organisms 45 Carboniferous 45 Medieval Warm Period 45 volcanism 45 multicellular 45 oceans 44 atmospheric concentrations 44 species extinctions 44 aridity 44 nitrogen fixation 44 temperate regions 44 climate 44 thermosphere 44 warmer winters 44 glacial melt 44 plate tectonics 44 boreal forests 44 stratospheric ozone 44 PETM 44 Cretaceous Period 44 isoprene 43 icecap 43 climatically 43 ozone depletion 43 climatic 43 abiotic 43 mammals 43 greenhouse gas concentrations 43 preindustrial 43 Microorganisms 43 mid latitudes 43 permafrost 43 glaciers melt 43 Ice Age 43 Cretaceous 42 oceanic 42 aerosol particles 42 epochs 42 isotopic 42 Antarctic 42 climatological 42 woolly mammoths 42 ocean acidification 42 Mesozoic 42 atmospheric chemistry 42 glaciers 42 marine reptiles 42 anoxic 42 extinction 42 geomagnetic 42 lake sediments 42 sunspot cycle 42 polar caps 42 Eocene 42 methane hydrate 41 desiccation 41 dynamical 41 marine organisms 41 phytoplankton 41 oxygen isotopes 41 landmasses 41 species 41 dinosaurs roamed