- Macalester College
- Macau University of Science and Technology
- Macquarie University [Sydney]
- Magellium
- Main Astronomical Observatory of NAS of Ukraine
- Maison de la Simulation
- Maison de l'Orient et de la Méditerranée - Jean Pouilloux
- Maison des Sciences de l'Homme et de l'Environnement Claude Nicolas Ledoux (UAR 3124)
- Maison des Sciences Humaines de Champagne-Ardenne
- Malaysian Meteorological Department
- Malin Space Science Systems
- Manchester Metropolitan University
- Manipal Academy of Higher Education
- MANSiD Research Center [Suceava]
- Maria Curie-Sklodowska University
- Marine Hydrophysical Institute
- Marine Institute [Ireland]
- Marine Physical Laboratory
- Marine Science Institute [Port Aransas]
- Mariolopoulos-Kanaginis Foundation for the Environmental Sciences
- Martin Fisher School of Physics
- Martin Ryan Institute
- Maryland Department of the Environment
- Masaryk University [Brno]
- Massachusetts Institute of Technology
- Massachusetts Maritime Academy
- Materials and Engineering Research Institute [Sheffield]
- Materials Research and Technology Department
- Matériaux, Défauts et IRradiations
- Matériaux et Nanosciences Grand-Est
- Matériaux, ingénierie et science [Villeurbanne]
- Matériaux, Rayonnements, Structure
- Mathématiques et Informatique Appliquées
- Mathematisches Institut [München]
- Matière et Systèmes Complexes
- Matsue National College of Technology
- Mauna Loa Observatory
- Max Planck Advanced Study Group at CFEL
- Max-Planck-Gesellschaft
- Max-Planck-Institut
- Max Planck Institute for Astronomy
- Max Planck Institute for Astrophysics
- Max Planck Institute for Biophysical Chemistry
- Max Planck Institute for Chemistry
- Max Planck Institute for Dynamics and Self-Organization
- Max Planck Institute for Extraterrestrial Physics
- Max Planck Institute for Human Cognitive and Brain Sciences [Leipzig]
- Max Planck Institute for Intelligent Systems [Tübingen]
- Max Planck Institute for Marine Microbiology
- Max Planck Institute for Meteorology
- Max Planck Institute for Nuclear Physics
- Max-Planck-Institut für Astronomie
- Max-Planck-Institut für Astrophysik
- Max-Planck-Institut für Biochemie = Max Planck Institute of Biochemistry
- Max-Planck-Institut für Biogeochemie
- Max-Planck-Institut für Chemie
- Max-Planck-Institut für Dynamik und Selbstorganisation
- Max-Planck-Institut für Extraterrestrische Physik
- Max-Planck-Institut für Gravitationsphysik ( Albert-Einstein-Institut )
- Max-Planck-Institut für Kernphysik
- Max-Planck-Institut für Meteorologie
- Max-Planck-Institut für Radioastronomie
- Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
- Max Planck Society
- McDonald Observatory
- McGill University = Université McGill [Montréal, Canada]
- McMaster University [Hamilton, Ontario]
- Medgar Evers College
- Médiation Scientifique Inria
- MÉDIATIONS - Sciences des lieux, sciences des liens
- Medical Imaging, Physics and Technology [Oulu]
- Mekelle University
- Melbourne School of Engineering [Melbourne]
- Memorial University of Newfoundland = Université Memorial de Terre-Neuve [St. John's, Canada]
- Mengcheng National Geophysical Observatory
- Mercator Océan
- Mesoscale Atmospheric Processes Laboratory
- Méso-Star
- MetAir AG
- Met Analytics Inc. [Toronto]
- MeteoConsult Paris
- Météo-France
- Météo-France Direction Interrégionale Sud-Est
- MeteoModem
- MeteoModem Company
- METEORAGE
- Meteorological Department (St. Maarten)
- Meteorological Institute [Hamburg]
- Meteorological Observatory Hohenpeissenberg (MOHp)
- Meteorological Research Institute [Tsukuba]
- Meteorologische Messtechnik GmbH
- Meteorologisches Institut [Bonn]
- Meteorologisches Institut [Hamburg]
- Meteorologisches Institut München
- Meteorologisches Observatorium Hohenpeißenberg
- Meteorology and Air Quality Department [Wageningen]
- Meteorology and Air Quality Group
- Meteotest
- Méthodes d'Analyses pour le Traitement d'Images et la Stéréorestitution
- Méthodes et Outils pour la Conception Intégrée de Systèmes
- MetOffice
- Met Office Climate Research Division
- Met Office Hadley Centre
- Met Office Lerwick
- Michigan State University [East Lansing]
- Michigan State University System
- Michigan Technological University
- Micrometeorology Group [Bayreuth]
- Microtel LLC
- Microtell LLC
- Mid-Atlantic Mass Spectrometry Laboratory
- Middle East Technical University [Ankara]
- Middle Tennessee State University [Murfreesboro]
- MIIT Key Laboratory of Space Environment monitoring and Information Processing
- Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols
- Military University of Technology
- Milken Institute School of Public Health
- Millennium Nucleus Center for Ecology and Sustainable Management of Oceanic Island
- Miller Institute for Basic Research in Science
- Minerva University
- Mines Paris - PSL (École nationale supérieure des mines de Paris)
- Ming Hsieh Department of Electrical Engineering [Los Angeles]
- Mini-Mass Consulting, Inc.
- Ministère de la Défense
- Ministère de la santé
- Ministère de l'écologie, du développement durable et de l'énergie
- Ministère de l'économie et des finances
- Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche
- Ministère de l'Enseignement Supérieur et de la Recherche Scientifique [Algérie]
- Ministère des Mines, de l'Energie et de l'Eau
- Ministério da Ciência, Tecnologia e Inovação
- Ministry of Agriculture [Guyana]
- Ministry of Defence (UK)
- Ministry of Natural Resources of China
- Ministry of Science and Technology
- Ministry of Science, Technology and Innovation [Malaysia]
- Ministry of the Environment Finland
- Misericordia University
- MIT Department of Architecture
- MIT Department of Civil and Environmental Engineering
- MIT Haystack Observatory
- MIT Kavli Institute for Astrophysics and Space Research
- MIT Lincoln Laboratory
- MIT Parsons Laboratory
- Modélisation des Surfaces et Interfaces Continentales
- Modélisation du climat
- Modélisation et Méthodes Statistiques Avancées
- Modélisation INVerse pour les mesures atmosphériques et SATellitaires
- Modelling the Earth Response to Multiple Anthropogenic Interactions and Dynamics
- MOE Key Laboratory of Semi-Arid Climate Change
- Mohammed Bin Rashid Space Center
- MOLTECH-Anjou
- Monash university
- Monash University [Clayton]
- Monash Weather and Climate
- Mongolian Academy of Sciences
- Mongolia Research Center for Astronomy and Geophysics
- Montana State University
- Montanuniversität Leoben
- Montessori-Zentrum Hofheim e.V.
- Morgan State University
- Morton K. Blaustein Department of Earth and Planetary Sciences [Baltimore]
- Moscow Center for Fundamental and Applied Mathematics
- Moscow Institute of Physics and Technology [Moscow]
- Moscow Power Engineering Institute
- Moscow State University of Geodesy and Cartography
- Mosecomonitoring Environmental Protection Institution
- Mount Holyoke College
- MRC-PHE Centre for Environment and Health
- MSU Faculty of Geography [Moscow]
- MTA Centre for Energy Research
- MTA-ELTE Research Group for Geology, Geophysics and Space Sciences
- MTA-SZTE Research Group on Photoacoustic Spectroscopy
- Mullard Space Science Laboratory
- Museo Nacional de Ciencias Naturales [Madrid]
- Muséum national d'Histoire naturelle
- Myasishchev Design Bureau