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(Click for frequent words.) 57 Velicogna 56 satellite altimetry 55 glaciological 55 Kristin Laidre 54 Hegerl 54 Hamish Pritchard 54 Jevrejeva 53 IFM GEOMAR 53 Rignot 53 Jay Zwally 53 Glaciology 52 Le Quéré 52 Pedro Martinez Arbizu 52 Aberdeen Oceanlab 52 Nils Axel Morner 52 subsurface ocean 52 Ola Johannessen 52 Fred Grassle 51 Josefino Comiso 51 altimetry 51 Stephane Udry 51 Abdalati 51 Shad O'Neel 51 Alexander Goncharov 51 Scripps Oceanography 51 atmospheric oceanic 50 Eric Rignot 50 Dikpati 50 Jane Ferrigno 50 Zapol 50 ESRL 50 Dronning Maud Land 50 Haymet 50 Georg Kaser 50 Stefan Rahmstorf 50 AMSR E 50 Angelika Brandt 50 Physique du Globe 49 Otto Bliesner 49 Amundsen Sea 49 Natalia Shakhova 49 Danovaro 49 Caspar Ammann 49 Rahmstorf 49 Bindschadler 49 Wilfried Haeberli 49 Paleoclimate 49 Laptev Sea 49 surface temperatures SSTs 49 sheet Summerhayes 49 Sermilik Fjord 49 Henk Brinkhuis 49 subseafloor 49 oceanic circulation 49 Canadell 48 Behrenfeld 48 Cayman Trough 48 Comiso 48 Törnqvist 48 Schmittner 48 Atlantic Multidecadal Oscillation AMO 48 Richard Camilli 48 Shuang Zhang 48 geoid 48 Shirshov Institute 48 Serreze 48 Glikson 48 Glaciologists 48 thermal inertia 48 Lamont Doherty 48 mantle plumes 48 ESA Envisat satellite 48 Finnish Meteorological 48 Paal Prestrud 48 Shakhova 48 Kossin 48 Professor Ove Hoegh 48 Laidre 48 Svalbard archipelago 48 Julienne Stroeve 48 radar altimetry 48 mid Pliocene 48 Willerslev 48 Zeebe 48 Petter Kristensen 48 Villy Christensen 48 Mojib Latif 47 aerosol concentrations 47 supercooling 47 abyssal plain 47 Weiqing Han 47 Luterbacher 47 Oceanography Centre 47 Norwegian polar explorer 47 Gerald Meehl 47 Ryskin 47 coccolithophores 47 Waleed Abdalati 47 Greenland glacier 47 Inez Fung 47 TrES 4 47 Geophysical Laboratory 47 Demian Chapman 47 microbialites 47 Global Biogeochemical Cycles 47 Paerl 47 oligotrophic 47 Jonathan Lunine 47 cryovolcanism 47 CIRES 47 Synte Peacock 47 Professor Hoegh Guldberg 47 Brunt Ice Shelf 47 Trembanis 47 Venusian atmosphere 47 superheavy elements 47 CSIRO Wealth 47 Muller Karger 46 seabed sediments 46 Scambos 46 Kay Bidle 46 Samuel Wickline 46 IFREMER 46 glacial earthquakes 46 Ontario Lacus 46 molten lava flowing 46 Bill Patzert 46 Nares Strait 46 Fiskeriforskning 46 Brendan Godley 46 interannual variability 46 Rasik Ravindra 46 carbonate ion 46 Henry Gholz 46 Pierre Simon Laplace 46 Jakobshavn Isbrae 46 hyper saline 46 Makiko Sato 46 GJ#b 46 Weddell Sea 46 Oceanology 46 Physical Oceanography 46 sea hydrothermal vents 46 Nansen Environmental 46 Amundsen Sea Embayment 46 NASA QuikScat satellite 46 Natalia Rybczynski 46 ° C warmer 46 Rossby waves 46 JOIDES Resolution 46 medieval archeology 46 Georgina Mace 46 Igor Semiletov 46 Georgi Mandushev 46 microplastics 46 Nikku Madhusudhan 46 Mark Serreze 46 Siple Dome 46 University Lamont Doherty 46 iceberg calving 46 polar vortex 46 Atmospheric Science RSMAS 46 Carnegie Institution Geophysical 46 Southampton NOCS 46 Isabella Velicogna 46 contamination Nishiyama 46 scientific journal Proceedings 46 Syrtis Major 46 seafloor methane 46 journal Geophysical Research 46 midlatitudes 46 Fleet Numerical Meteorology 46 crustal thickness 46 glacial melting 46 Wieslaw Maslowski 45 icesheet 45 neutrino telescope 45 Mark Thiemens 45 Appy Sluijs 45 Technology SOEST 45 KIPAC 45 barometric pressures 45 Maria Karayiorgou 45 bathymetry 45 paleoclimatic 45 hydrosphere 45 journal Behavioral Ecology 45 using multibeam sonar 45 CarbonTracker 45 Centers Helmholtz Gemeinschaft 45 tides currents 45 teleconnections 45 Odd Aksel Bergstad 45 glacial fjord 45 Niiler 45 Gerta Keller 45 Natalie Mahowald 45 Shuguang Zhang 45 Jacqueline Savitz marine 45 chlorophyll concentrations 45 Alicja Wolk 45 Pierre Friedlingstein 45 Orjan Gustafsson 45 Jovian moon 45 mantle convection 45 upwellings 45 acidic oceans 45 Ken Buesseler 45 outlet glaciers 45 Last Glacial Maximum 45 polar oceans 45 Maya Tolstoy 45 hydrography 45 lithosphere 45 Lothar Stramma 45 Glaciologist 45 abyssal depths 45 Sekercioglu 45 Trey Ideker 45 anomalously warm 45 Gerasimos Papadopoulos 45 subpolar 45 Margarita Marinova 45 downwelling 45 Eske Willerslev 45 subglacial lakes 45 Alfred Wegener Institute 45 climate modeller 45 Sigmundsson 45 Michael Studinger 45 climate modeler 45 deglaciation 45 Ira Leifer 45 Glaciers melting 45 COROT 7b 45 Microbiologist Cynan Ellis 45 Hoegh Guldberg 45 Indian climatologist Rajendra 45 coastal upwelling 45 Gerald Meehl senior 45 Svante Arrhenius 45 NCEAS 45 sediments deposited 45 Indian Ocean Dipole 44 Paul Sabatier 44 cryosphere 44 Ian Joughin 44 Jupiter moon Io 44 Pakrasi 44 Envisat ASAR 44 ocean basins 44 Mandushev 44 Volker Liebig ESA 44 Mike Raupach 44 paleoenvironmental 44 Henshilwood 44 bathymetric 44 Hik 44 McMurdo Dry Valleys 44 Andreas Muenchow 44 Skvarca 44 Schladow 44 paleoclimatology 44 Vostok Station 44 permafrost degradation 44 Okeanos Explorer 44 Aiguo Dai 44 Erik Seiffert 44 axial tilt 44 Ron O'Dor 44 boreal regions 44 climate modellers 44 moulins 44 Planetary Change 44 Brigham Grette 44 Vrije University 44 Sugata Hazra 44 subarctic 44 terrestrial biosphere 44 chlorine monoxide 44 journal Climatic Change 44 hydrothermal vent 44 basaltic rocks 44 Didier Raoult 44 microscopic radioactive particles 44 glaciologists 44 Konrad Steffen 44 Fram Strait 44 Christophe Sotin 44 Corinne Le Quere 44 British Antarctic Survey 44 Martin Wikelski 44 Hans von Storch 44 Institutet 44 paleoclimate 44 missing baryons 44 Cosmic Microwave Background 44 Xavier Bonfils 44 Gas hydrates 44 Ignatius Rigor 44 Mikucki 44 NCAR scientist 44 Meg Urry 44 Late Paleozoic 44 airglow 44 glacier shrinkage 44 Buesseler 44 Lubchenko 44 Stas Barabash 44 AR Ravishankara 44 sub glacial lakes 44 tiny single celled 44 Paquay 44 Lida Pet Soede 44 Walruses dive 44 Coral bleaching 44 carbon fluxes 44 deepwater corals 44 Toba eruption 44 Romero Lankao 44 AERONET 44 Ray Berkelmans 44 tropopause 44 NOAA Geophysical Fluid 44 Agulhas Current 44 biogeochemical 44 Gaetano Di Achille 44 Gakkel Ridge 44 Edith Widder 44 Sheldon Drobot 44 Bramley Murton 44 atmospheric methane 44 tropical troposphere 44 aragonite 44 geochemists 44 Methane hydrates 44 thermohaline circulation 43 isostatic rebound 43 Tumi geologist 43 temperature reconstructions 43 Markus Jokela 43 Ferraccioli 43 magma ocean 43 phytoplankton biomass 43 Leif Kullman 43 Plate tectonics 43 martian meteorites 43 Bert Metz 43 Antarctic glaciers 43 glaciers recede 43 antarctic 43 Universite Pierre 43 Jan Gunnar Winther 43 anthropogenic warming 43 Thierry Chopin 43 post perovskite 43 Jeffrey Bozanic 43 midlatitude 43 Puijila 43 Boisserie 43 Drew Shindell 43 Guldberg 43 planet Gliese #c 43 Oceanographic Studies 43 microbial ecosystems 43 hydrodynamics 43 glacial melt 43 oceanographers 43 et Marie Curie 43 Hans Peter Uerpmann 43 Lake Untersee 43 Synolakis 43 Dorthe Dahl Jensen 43 Anvers Island 43 megathrust 43 Roland Burgmann 43 Russ Hopcroft 43 Ocean Observatories Initiative 43 geothermal gradient 43 forams 43 Kounaves 43 Geophysical Research 43 abyssal plains 43 Mud volcanoes 43 Ilya Prigogine 43 NAVOCEANO 43 Gina Solomon 43 scientific journal PNAS 43 palaeoclimate 43 methane hydrates exist 43 undersea volcanoes 43 Waleed Abdalati director 43 Fomalhaut b 43 -# degrees Fahrenheit [002] 43 Wallace Broecker 43 warship Vasa 43 glaciers melting 43 V. Ramanathan 43 Brenda Ekwurzel climate 43 clathrates 43 extratropical cyclones 43 Giorgos Stavrakakis 43 volcanic arcs 43 Eduardo Zorita 43 Dr van Ommen 43 Shanna Swan 43 NCAR scientist Synte Peacock 43 Ottmar Edenhofer 43 Till Roenneberg 43 Antarctic Dry Valleys 43 deep convective clouds 43 van der Leeuw 43 Robert Bindschadler 43 Domack 43 katabatic winds 43 geomicrobiology 43 Norwegian Polar 43 Service WGMS 43 Ecology Letters 43 El Niño La Niña 43 Spitzbergen 43 geodynamics 43 Transantarctic Mountains 43 GFZ 43 lowermost mantle 43 Greenland ice 43 Condensed Matter 43 Warmer oceans 43 Ifremer 43 permafrost 43 ostracods 43 Schellnhuber 43 continental rifting 43 Redei 43 Vladimir Romanovsky 43 William Happer 43 neutrino detectors 43 Lophelia 43 Steve Lohrenz biological 43 teleost fish 43 forecaster Helen Chivers 43 Isaac Wirgin 43 permafrost thaws 43 Gregory Asner 43 seafloor sediments 43 Mauna Loa Observatory 43 tidewater glaciers 43 journal Astrobiology 43 Alboran Sea 43 CoML 43 PN Lebedev Physical 42 Andrew Derocher 42 SeaWiFS 42 Polar Regions 42 Dry Valleys 42 Helheim glacier 42 Scott Luthcke 42 Son Nghiem 42 Seepage detected 42 Sorcerer II 42 Roger Revelle 42 Centre UNEP WCMC 42 HARBOR BRANCH 42 cirrus clouds 42 roiling shark infested 42 subantarctic 42 southern latitudes 42 Quetelet 42 Kashlinsky 42 ICESCAPE 42 cave stalagmites 42 Margaret Leinen 42 Oceanographers 42 cablegate archive 42 DiGiusto 42 polar icecap 42 Ross Salawitch 42 Eric Steig 42 Adélie penguins 42 Greg Bargmann 42 sulphate aerosols 42 hydrometeorological 42 equatorial regions 42 Alan Robock 42 meridional overturning circulation 42 upper troposphere 42 Eemian 42 Miami Rosenstiel 42 icefields 42 CO2 fluxes 42 molecular systematics 42 laser altimetry 42 Nature Geoscience 42 hidden crevasses 42 GKSS Research 42 Henrik Svensmark 42 permafrost melts 42 biogeochemistry 42 Springer journal Naturwissenschaften 42 Institute MBARI 42 Helheim 42 Antarctica EPICA 42 glacial cycles 42 Perito Moreno 42 journal Monthly Notices 42 abyssal 42 Professor Monty Priede 42 bioresource 42 subglacial lake 42 Benfey 42 melting glacial 42 J. Baumol 42 Space Physics 42 Robert Corell 42 geomagnetism 42 Hany Farid 42 Svalbard islands 42 UNEP WCMC 42 mass beachings 42 Qiang Fu 42 Ice Coring 42 photosphere 42 journal Palaios 42 rougher seas 42 ocean eddies 42 Richard Binzel 42 Kilimanjaro glaciers 42 Bruce Molnia 42 Berkeley Seismological Laboratory 42 Emile Okal 42 Climate Experiment GRACE 42 Noah Diffenbaugh 42 Palaeozoic sedimentary 42 Czech Hydrometeorological Institute 42 Claes Wahlestedt 42 Andres Kasekamp 42 author Boris Worm 42 interglacial periods 42 Yun Qian 42 Frank Muller Karger 42 subglacial 42 oxidized mercury 42 lunar magma 42 Biogeography 42 tidewater glacier 42 Syed Hasnain 42 Hellas Basin 42 Ernst Peebles 42 thermosphere 42 Luann Becker 42 Mars Climate Sounder 42 copepod 42 mesosphere 42 Oceanographer 42 Govindasamy Bala 42 Barbara Sahakian 42 Scott Mabury 42 Nils Stenseth 42 advection 42 #.#C #.#C 42 Abdussamatov 42 journal PNAS 42 Valter Longo 42 Recherche Medicale 42 whale beachings 42 NASA satellites orbiting 42 oceanic crust 42 MARSIS 42 Observatory LDEO 42 atmospheric chemistry 42 Lake Vui 42 E. Romanovsky 42 polar plateau 42 Wyplosz 42 multi decadal 42 reef habitats 42 distant supernovae 42 Makovicky 42 Geobiology 42 COET 42 paleoclimatologist 42 Prasad Gogineni 42 crustal movements 42 Cassini flyby 42 interglacial period 42 CIESIN 42 Arctic Coring Expedition 42 El Nino La Nina 42 Julie Brigham Grette 42 Geophysical Fluid Dynamics 42 Crozet Islands 42 Vörösmarty 42 KT boundary 42 Ground penetrating radar 42 Tulaczyk 41 chromosphere 41 Stockholm Resilience 41 Shuhai Xiao 41 Ove Hoegh Guldberg 41 Peter Gotzsche 41 aerosol particles 41 dustier stormier atmosphere 41 Rosenstiel School 41 mid latitudes 41 #.#oC [001] 41 #.#-#.# degrees Fahrenheit [002] 41 Medspiration 41 NSIDC 41 Oceans Flagship 41 molten magma 41 UKIRT 41 tight bun hairdos 41 fissure eruption 41 mammal fossils 41 Atmospheric Physics 41 atmospheric concentrations 41 Climate Impact Assessment 41 Solar Terrestrial Physics 41 subducting plate 41 MARUM 41 Jianjun Yin 41 Ken Caldeira 41 Physical Geography 41 journal PLoS Genetics 41 Navy copter crashes 41 Jaakko Kaprio 41 planet Gliese #g 41 GISS analysis 41 Cryosphere 41 oceanographic 41 icecaps 41 Nature Geoscience journal 41 Stephen Palumbi 41 Beaked whales 41 Corot 7b 41 Stephen O'Rahilly 41 magnetic reconnection 41 Smol 41 Andrew Balmford 41 Bill Chameides 41 Francesca Dominici 41 journal Epidemiology 41 polar regions 41 Ny Alesund 41 Oecologia 41 polar 41 polar caps 41 PS Goel 41 Biogeochemistry 41 tropical coral reefs 41 USArray 41 thermal vents 41 atmospheric circulations 41 Alexandrium fundyense 41 planets atmospheres 41 Alexandrium 41 ostracodes 41 Michel Brunet 41 Pacific hake whitefish 41 volcanically active 41 Martin Haehnelt 41 Tor Bjerkedal report 41 Pep Canadell 41 Mars Analog Svalbard 41 active volcanism 41 hydrothermal venting 41 Simin Nikbin Meydani 41 Jean Pierre Bibring 41 Hydrates 41 underwater volcanos 41 Ulysses spacecraft 41 Copter crashes 41 glacial ice 41 CoRoT 9b 41 archaic ungulates 41 Mien Chie Hung 41 UM Rosenstiel School 41 Medieval Warm Period MWP 41 Tharsis Rise 41 mud volcanoes 41 journal Ethology 41 polar ice 41 methane clathrates 41 Helmholtz Association 41 Martin Krkosek 41 Claudia Tebaldi 41 Poul Holm 41 UCSD Scripps Institution 41 Sheet WAIS 41 Walt Meier 41 science journal Nature 41 plantlike bacteria 41 Jonathan Lunine Cassini 41 biogeographic 41 paleomagnetic 41 Haraldur Sigurdsson 41 Climate Impact 41 Hongbin Qu chief 41 phytoplankton populations 41 van der Hilst 41 Rychard Bouwens 41 Keeling Curve 41 earliest hominid 41 glaciers retreating 41 Moyà Solà 41 icy moons 41 ocean ridges 41 Lake Vostok 41 Chris Waythomas 41 lava erupting 41 seals walrus 41 pika habitat 41 Malte Meinshausen 41 SPAMfighter employs 41 Skidaway Institute 41 Cassini radar 41 William Kininmonth 41 deserts jungles 41 seismic hydrographic 41 Gravitational waves 41 Nweeia 41 stratospheric clouds 41 tectonic plate boundaries 41 Arctic oscillation 41 opossum shrimp 41 journal Nature Photonics 41 Pollution Bulletin 41 Sumatra Andaman earthquake 41 explorer Sylvia Earle 41 Margaret Honein 41 alpine glaciers 41 hydrological cycle 41 René Descartes 41 Tornqvist 41 Anders Wimo 41 icebreaker Healy 41 floods heatwaves droughts 41 Nankai Trough 41 Timothy Mousseau 41 starfish crabs 41 ozone depletion 41 Oceanlab 41 gaseous planet 41 Institution WHOI 41 Mars Squyres 41 Greenland glaciers 41 droughts heatwaves floods 41 geoneutrinos 41 Tad Pfeffer 41 icebergs scour 41 Molnia 41 Jay Famiglietti 41 Bert Bolin 41 Maria Zuber 41 Atmospheric Prediction 41 degrees Fahrenheit warmer 41 Robock 41 moon Enceladus 41 Nathan Kaib 41 coral calcification 41 Eric Hoffmayer 41 sulfur isotopes 41 cosmic ray flux 41 oxygen isotope 41 scatterometer 41 seawater pH 41 Erlangen Nuremberg 41 Mathematical Statistics 41 Valeria Criscione 41 subduction zone earthquake 41 VY Canis Majoris 41 hydrate deposits 41 Longmen Shan fault 41 Jake Vander Zanden 41 Martian dunes 40 Bette Otto Bliesner 40 GHG concentrations 40 Anthony Swerdlow 40 Yuan Gangming 40 polar latitudes 40 paleobiologists 40 Synthesis NCEAS 40 Matthew Meselson 40 Rupa Kumar Kolli 40 RSMAS 40 penguin rookery 40 Antarctic ice 40 Frank Postberg 40 Raphael Kudela professor 40 hypersaline 40 palaeo 40 paleoclimatologists 40 Ross Ice Shelf 40 Martin Sommerkorn 40 auroral activity 40 Laboratory MBL 40 Dr. Sylvia Earle 40 atmospheric CO2 concentration 40 Kosaki 40 atmospheric deposition 40 Geoff Schladow 40 Przeworski 40 geologically active 40 Whillans Ice Stream 40 journal Cerebral Cortex 40 Richard Lindzen professor 40 Ted Scambos 40 atmospheric chemist 40 research vessel Polarstern 40 Joachim Heinrich 40 volcanic vents 40 Pu'u O'o crater 40 Bioinspiration 40 glaciology 40 foehn 40 Jonathan Patz 40 vertebrate zoology 40 Weddell seals 40 Philosophical Transactions 40 equatorial Pacific Ocean 40 Chemical Physics 40 Terre Adelie 40 habitable zones 40 Carl Wunsch 40 Image NASA JPL 40 Alberto Saal 40 Casadevall 40 M. Asara 40 Antarctic icecap 40 marine geologist 40 smoggy atmosphere 40 lightless depths 40 benthos 40 gigatonne 40 geomorphology 40 #.#C warmer 40 International Geosphere Biosphere 40 IODP 40 Von Frese 40 Blainville beaked whales 40 Regenstrief Institute affiliated 40 Greenland icecap 40 ACIA 40 deltaic 40 Biomedical Magnetic Resonance 40 glacier melt 40 polar voyages 40 Anthony Barnosky 40 Rom Lipcius 40 journal Geology 40 hydrologic cycle 40 Glacier Monitoring 40 George Ebers 40 Cabrol 40 Amstrup 40 galaxy formation 40 IPCC Intergovernmental Panel 40 Kutluk Oktay 40 Opposes drilling 40 Jay Lawrimore chief 40 Jane da Mosto 40 Frumhoff 40 Oceanography 40 icebreaker Polar Sea 40 CfA 40 sperm whales killer whales 40 Jorn Hurum 40 submersible Alvin 40 albedo feedback 40 Johannes Lehmann 40 GJ #b [002] 40 Jakobshavn 40 scientist Jay Zwally 40 Nature Geosciences 40 yedoma 40 Cuvier 40 Hanski 40 Swera district health 40 receding glaciers 40 S. Lindzen 40 Coast Guard icebreaker Healy 40 Photobiology 40 heatwaves floods droughts 40 Siberian Traps 40 Kirsten Bibbins Domingo 40 interglacial 40 David Wilcove 40 computational biologists 40 Lake Yoa 40 Limnology 40 gigatonnes 40 Carl Friedrich Gauss 40 biological oceanographer 40 New Phytologist 40 journal Nature Geoscience 40 Upper Jurassic 40 von Frese 40 Geophysical Sciences 40 Arctic icecap 40 Scarmeas 40 Pielke 40 Geodynamic Institute 40 southern supercontinent 40 springtime ozone 40 exosphere 40 Dendrochronology 40 Leschine 40 methane hydrates 40 Ecofys 40 tectonic stresses 40 meltwater 40 David Stuckler 40 Coral Reef Targeted 40 Rasenick 40 marine ecologists 40 Holocene epoch 40 Corinne Le Quéré 40 Josberger 40 calcium carbonate shells 40 Laila Sadler 40 Cryospheric Sciences Branch 40 seamounts 40 AGW theory 40 Bruce Wielicki 40 phytoplankton bloom 40 Ingraffea 40 planetary geology 40 Atmospheric Science 40 Joan Kleypas 40 supercomputer simulations 40 CryoSat mission 40 icy crust 40 Lotfi Zadeh 40 Himalayan river basins 40 seismogenic 40 disappearing glaciers 40 Arctic Ocean 40 #.#C above 40 Hans Geiger 40 glacial interglacial 40 atmospheric circulation 40 -# degrees Celsius [001] 40 Jules Blais 40 Jeffrey Kargel 40 Marco Festa Bianchet 39 Seamounts 39 Warmer seas 39 Matthias Mehl 39 biogeochemist 39 Bellingshausen Sea 39 hydrographic surveys 39 Robert Jedicke 39 Bering Glacier 39 Steve Palumbi 39 giant squid Architeuthis 39 Berkelmans 39 Ilkka Hanski 39 Rene Heroux 39 Biology Letters 39 colder denser 39 Climate Impacts Group 39 Enrico Fermi Institute 39 Alaskan glaciers 39 species extinctions 39 hydrated minerals 39 El Nino periodic 39 infalling gas 39 Paytan 39 Cryogenian 39 Oskarsson 39 spicules 39 atmospheric CO2 concentrations 39 Hoeppe 39 Antarctic Peninsula 39 chemical oceanographer 39 biometeorology 39 Gersberg 39 biogeochemical cycles 39 Vernon Asper 39 Clinical Biochemistry 39 Polar Observation 39 methane hydrate 39 Charcot Island 39 Haystack Observatory 39 Petrology 39 Neuroradiology 39 Tim Kusky 39 waves droughts floods 39 noctilucent clouds 39 Erik Asphaug 39 stalagmites 39 Metagenomics 39 Moderate Resolution Imaging 39 equatorial bulge 39 undersea volcanic 39 coldest driest 39 polynyas 39 Paul Mellars prehistory 39 poleward shift