“ The International Union of Geodesy and Geophysics : from different spheres to a common globe ”

Many environmental challenges facing society since the last century require international solutions. Examples include exploration of the Earth and its environment in space; exploration of our rivers, oceans, and atmosphere; climate change; securing clean water and energy; and understanding and mitigating disasters due to natural hazard events. Earth and space sciences lie at the heart of these challenges and occupy a central role in international agendas. The International Union of Geodesy and Geophysics (IUGG) has been coordinating and promoting international efforts in Earth and space sciences since 1919. Under IUGG’s umbrella, eight international scientific associations and several interdisciplinary bodies cover many disciplines of geoand space sciences and promote research of the Earth from its core and its space environment up to the Sun. Thousands of scientists from many nations and specific scientific disciplines have developed ways of cooperation through IUGG’s international associations and learned how to work together to promote geosciences. IUGG has been initiating, developing, and implementing international cooperative programs; setting scientific standards; developing research tools; educating and building capacity; and contributing to science for policy and science diplomacy. The purpose of this special issue (SI) is not to relay a definitive history of the development of international cooperation in the geosciences, but to summarize IUGG’s remarkable role during the 100-year span of its existence. The first part of the SI “The union: bringing together geophysical disciplines” begins with the present overview of the IUGG mission and structure, and the circumstances of its founding and early development are presented up to the beginning of World War II. The second article starts with recovery after World War II and addresses the years of extraordinary development of geophysical science through the International Geophysical Year (IGY; 1957–1958) and the concurrent evolution of IUGG structure and programs extending up to the General Assembly of 1999. The rapid advances that have occurred thus far into the 21st century are reviewed in the third article, and foresights on IUGG future development conclude this first part of the SI. Outstanding histories of each of the IUGG associations are then told. The second part of the SI “Around the earth: glaciers, rivers, air, and oceans” presents articles about the histories of the International Association of Cryospheric Sciences (IACS: past, present, and future of the International Association of Cryospheric Sciences), the International Association of Hydrological Sciences (IAHS: a brief history of hydrology), the International Association of Meteorology and Atmospheric Sciences (IAMAS: a century of international cooperation in atmospheric sciences), and the International Association for the Physical Sciences of the Oceans (IAPSO: tales from the ocean frontier). The third part of the SI “Within and on the earth: gravity, magnets, earthquakes, and volcanoes” presents articles about the histories of the International Association of Geodesy (The International Association of Geodesy: from an ideal sphere to an irregular body subjected to global change), the International Association of Geomagnetism and Aeronomy

Many environmental challenges facing society since the last century require international solutions.Examples include exploration of the Earth and its environment in space; exploration of our rivers, oceans, and atmosphere; climate change; securing clean water and energy; and understanding and mitigating disasters due to natural hazard events.Earth and space sciences lie at the heart of these challenges and occupy a central role in international agendas.
The International Union of Geodesy and Geophysics (IUGG) has been coordinating and promoting international efforts in Earth and space sciences since 1919.Under IUGG's umbrella, eight international scientific associations and several interdisciplinary bodies cover many disciplines of geo-and space sciences and promote research of the Earth from its core and its space environment up to the Sun.Thousands of scientists from many nations and specific scientific disciplines have developed ways of cooperation through IUGG's international associations and learned how to work together to promote geosciences.IUGG has been initiating, developing, and implementing international cooperative programs; setting scientific standards; developing research tools; educating and building capacity; and contributing to science for policy and science diplomacy.
The purpose of this special issue (SI) is not to relay a definitive history of the development of international cooperation in the geosciences, but to summarize IUGG's remarkable role during the 100-year span of its existence.The first part of the SI "The union: bringing together geophysical disciplines" begins with the present overview of the IUGG mission and structure, and the circumstances of its founding and early development are presented up to the beginning of World War II.The second article starts with recovery after World War II and addresses the years of extraordinary development of geophysical science through the International Geophysical Year (IGY;1957-1958) and the concurrent evolution of IUGG structure and programs extending up to the General Assembly of 1999.The rapid advances that have occurred thus far into the 21st century are reviewed in the third article, and foresights on IUGG future development conclude this first part of the SI.Outstanding histories of each of the IUGG associations are then told.
The second part of the SI "Around the earth: glaciers, rivers, air, and oceans" presents articles about the histories of the International Association of Cryospheric Sciences (IACS: past, present, and future of the International Association of Cryospheric Sciences), the International Association of Hydrological Sciences (IAHS: a brief history of hydrology), the International Association of Meteorology and Atmospheric Sciences (IAMAS: a century of international cooperation in atmospheric sciences), and the International Association for the Physical Sciences of the Oceans (IAPSO: tales from the ocean frontier).
The third part of the SI "Within and on the earth: gravity, magnets, earthquakes, and volcanoes" presents articles about the histories of the International Association of Geodesy (The International Association of Geodesy: from an ideal sphere to an irregular body subjected to global change), the International Association of Geomagnetism and Aeronomy Published by Copernicus Publications.
(IAGA: a major role in understanding our magnetic planet), the International Association of Seismology and Physics of the Earth's Interior (IASPEI: its origins and the promotion of global seismology), and the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI: from small beginnings to a vibrant international association).
This volume, proposed in 2014 by the IUGG Bureau, is the combined effort of a number of authors and advisors, including past and current IUGG and association officers.We are grateful to Franz Kuglitsch and Katina Rogers Roopchansingh for their technical and editorial assistance, to Hans Volkert for proposing the title of this SI and editorial support, and to reviewers for their constructive comments and suggestions for revision of the initial manuscripts of the papers published in the SI.The IUGG archives, curated by the American Institute of Physics Center for the History of Physics (Gregory Good, director), located in College Park, MD, USA, were heavily consulted in preparation for this SI, and we acknowledge their helpful staff.We are very thankful to Kristian Schlegel, HGSS editor-in-chief, for his enthusiastic efforts and assistance in producing the SI.