Jule Gregory Charney (January 1, 1917 – June 16, 1981) was an American meteorologist who played an important role in developing numerical weather prediction and increasing understanding of the general circulation of the atmosphere by devising a series of increasingly sophisticated mathematical models of the atmosphere. His work was the driving force behind many national and international weather initiatives and programs. Considered the father of modern dynamical meteorology, Charney is credited with having "guided the postwar evolution of modern meteorology more than any other living figure." Charney's work also influenced that of his close colleague Edward Lorenz, who explored the limitations of predictability and was a pioneer of the field of chaos theory.
Biography Charney was born in San Francisco, California, on January 1, 1917, to Jewish-Russian immigrants Ely Charney and Stella Littman, tailors in the garment industry. Charney spent most of his early life in California. After a 20-month battle with cancer, he died in Boston at the Sidney Farber Cancer Institute at the age of 64.
Education Charney earned his undergraduate and graduate degrees at UCLA, culminating in a Ph.D. in physics in 1946. His Ph.D. dissertation, titled “The Dynamics of Long Waves in a Baroclinic Westerly Current” comprised the entire October 1947 issue of the Journal of Meteorology. The paper was influential because it emphasized the influence of “long waves” in the upper atmosphere on the behavior of the entire atmosphere rather than the more traditional emphasis on the polar front and also provided a way of analyzing perturbations along these waves that was both physically insightful and mathematically rigorous.
Career and legacy Charney began his career at his alma mater, UCLA, as an instructor in physics and meteorology from 1941 to 1946. In 1946, Charney became a research associate at the University of Chicago under Carl-Gustav Rossby, a Swedish-born American meteorologist whose theories of large-scale air movements helped revolutionize meteorology. From 1947 to 1948, Charney held a National Research Council postgraduate fellowship at the University of Oslo in Norway. During this year, he developed a technique known as the “quasi-geostrophic approximation” for calculating the large-scale motions of planetary-scale waves. Charney's quasi-geostrophic vorticity equations allowed for concise mathematical description of large-scale atmospheric and oceanic circulations, enabling future numerical weather prediction work.
Numerical weather prediction In 1948, Charney joined the Institute for Advanced Study (IAS) in Princeton, New Jersey, to explore the feasibility of applying digital computers to weather prediction as head of the Meteorological Research Group. Together with noted mathematician John von Neumann, Charney helped pioneer the use of computers and numerical techniques to improve weather forecasting, and played a leading role in efforts to integrate sea-air exchanges of energy and moisture into the study of climate. This collective work paved the way for the founding of NOAA's Geophysical Fluid Dynamics Laboratory. In 1954, Charney helped create the Joint Numerical Weather Prediction Unit, a collaboration between the U.S. Weather Bureau, Air Force, and Navy. Charney would later serve as a member of the Committee on Atmospheric Sciences of the National Academy of Sciences and as chairman of the academy's Committee on International Meteorological Cooperation. In those roles, he conceived and helped organize the Global Atmospheric Research Program, considered the most ambitious international effort in weather research ever undertaken.
Dynamic meteorology and oceanography In 1956, Charney left IAS to become a professor of meteorology and director of the Atmospheric and Ocean Dynamics Project at MIT, where for 25 years he made major contributions in dynamic meteorology and oceanography research, including large-scale atmospheric turbulence, feedback interactions between the oceans and atmosphere, the persistence of certain abnormal flow patterns in the atmosphere, and the relationship of such phenomena to droughts. Among his many fundamental contributions to the field, Charney identified “baroclinic instability,” the first convincing physical explanation for the development of mid-latitude cyclones. Charney identified the mechanism that explains the size, structure, and growth rate of mid-latitude weather systems, and is a ubiquitous phenomenon in rotating, stratified fluids like our oceans and atmosphere. From 1974 to 1977, Charney headed the meteorology department at MIT. In addition to his revolutionizing research, Charney is remembered as a charismatic and optimistic professor among former students from MIT, where he remained until his death in 1981. Students describe falling into “orbit around the Charney sun.” There is a library named in Charney's honor in the building that holds the MIT Department of Earth, Atmospheres and Planetary Sciences.
Charney Report In 1979, Charney chaired an "ad hoc study group on carbon dioxide and climate" for the National Research Council. The resulting 22-page report, "Carbon dioxide and climate: A scientific assessment," is one of the earliest modern scientific assessments about global warming. Its main conclusion can be found on page 2: "We estimate the most probable global warming for a doubling of CO2 to be near 3°C with a probable error of ± 1.5°C." This estimate of climate sensitivity has been essentially unchanged for over four decades, e.g., the IPCC Fourth Assessment Report (2007) says that "equilibrium climate sensitivity is likely to be in the range 2°C to 4.5°C, with a best estimate value of about 3°C. It is very unlikely to be less than 1.5°C. Values substantially higher than 4.5°C cannot be excluded, but agreement with observations is not as good for those values." In 2019 climate scientists celebrating the 40th anniversary of the Charney report said "In retrospect, the Charney report seems like the scientific equivalent of the handwriting on the wall...Their warning was accurate and remains more relevant than ever."
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