Related by context. Frequent words. (Click for all words.) 62 biosphere 58 hydrologic cycle 57 lifeforms 57 earths 57 atmospheric CO 56 abiotic 56 clathrates 55 atmospheric methane 55 plankton blooms 55 terrestrial ecosystems 55 methanogens 55 hydrological cycle 54 ecosphere 54 diatoms 54 biogeochemical 54 biogenic 54 Earth magnetosphere 54 aerosol particles 54 nitrogen fixation 54 multicellular 54 prokaryotes 53 phytoplankton blooms 53 atmospheric CO2 53 multicellular organisms 53 substorm 53 meteorite impacts 53 atmospheric carbon dioxide 53 solar nebula 53 habitable planet 53 osmium 52 atmospheric nitrogen 52 hydrothermal vent 52 species extinctions 52 tropospheric 52 decoherence 52 planktonic 52 evolutionary origins 52 CO -2 52 single celled 52 isotope ratios 51 humans 51 Hawking radiation 51 photosynthetic 51 nitrogen fixing 51 radioactive decay 51 single celled organisms 51 organisms 51 Geobacter 51 atmospheric chemistry 51 habitable planets 51 oceanic 51 galaxy formation 51 potent greenhouse gas 51 magnetic reconnection 51 Earthlike 51 radiative 51 radiative forcing 51 astrobiologists 50 polar vortex 50 WASP #b 50 stratospheric ozone 50 volcanic vents 50 Oort Cloud 50 methane hydrate 50 water vapor 50 planetary 50 CO2 concentrations 50 Cambrian explosion 50 dynamical 50 phytoplankton 50 organism 50 Snowball Earth 50 hydroxyl radicals 50 methane hydrates 50 microbial ecology 50 oceans 50 angiosperms 50 ecologies 50 deglaciation 50 Earth ozone layer 50 magmas 50 isoprene 50 thermodynamic 49 nucleation 49 Lake Vostok 49 vertebrate animals 49 Cyanobacteria 49 humankind 49 solar corona 49 diatom 49 biogeochemistry 49 biota 49 poleward 49 solar irradiance 49 supernova explosion 49 magnetosphere 49 Solar flares 49 protoplanetary disk 49 unicellular 49 chirality 49 photosynthesis