History of Climatology

Climatology is the branch of atmospheric science dedicated to the description and analysis of the Earth’s climate and its biospheric interactions over extended periods of time. Climatology began as the observation and description of weather on subcontinental and continental levels. The ancient Greeks believed that climates were nothing more than temperature gradients varying along latitude belts. Climatology was primarily observational speculation prior to the dawning of the scientific age, when devices for measuring and studying weather were invented, and the keeping of systematic weather records began.

Early Attempts to Understand the Climate The scientific roots of climatology, a subdiscipline of meteorology until the late 20th century, were planted in the work of Edmund Halley’s 1686 mapping of the trade winds and his assertion of a relationship between solar heating and atmospheric change. His work introduced the idea of weather and climate systems interacting with the physical features of the Earth. It was not until the early 20th century that the understanding of this interaction moved beyond observation to analysis and synthesis. Prior to the mid-20th century, climatology was divided into two subdisciplines: regional climatology, studying subcontinental and continental weather and climates; and physical climatology, gathering and analyzing the statistical data related to weather and climates. Climatology sought to describe and understand normal climates, but there was little understanding of the timescale or breadth of climate change, save for the ice age or of climate as a global system of interrelated climates forming a whole that is more than its parts.

Vilhelm Bjerknes’s pre-1920s work on midaltitude cyclones led him to create a model of atmospheric change based on hydrodynamics and thermodynamics. Bjerknes’s work and Lewis Fry Richardson’s 1920s equation-based weather predictions led to a rudimentary three-dimensional atmospheric model. However, the complexity of the equations and magnitude of the calculations made the understanding of climate systems nearly impossible, until the availability of high-speed computers in the 1950s made numerical modeling of climate systems possible. This expansion led to the formation of the new subdisciplines of dynamic meteorology and dynamic climatology.

The second major impetus for change in climatology in the 20th century was World War II. World War II demonstrated the advantage to modern warfare of predictive meteorology when, for example, it was used to forecast the weather for June 6, 1944, the day of the invasion by the Allies of Nazi-occupied France. These conventional military applications, along with the need to understand weather patterns and climates as they related to the possibility of nuclear war and the expanding agricultural, industrial, communication, and transportation technologies, led to increased funding for training, research, and education in climatology.

Several key figures emerged in the academic world as the regard for meteorology and climatology increased. Carl-Gustav Rossby created the Department of Meteorology at the University of Chicago in 1942, and there, with a team of researchers, developed the first physical climate models that viewed the entire planet as an integrated physical whole, or system. Reid Bryson, a World War II military meteorologist, left the geography department at the University of Wisconsin, Madison, to form a meteorology department there. He then established, in 1962, a climate research center at Madison after receiving National Science Foundation funding. Massachusetts Institute of Technology mathematician and meteorologist Edward N. Lorenz, also a World War II military meteorologist, began applying chaos theory to the atmosphere in the 1960s, and his theories were integrated into the increasingly complex atmospheric modeling relegated to computers. Despite these advances, the U.S. Weather Bureau continued to view climatology only as a tool for forecasting.

Concurrent with this growth of meteorology and climatology as academic disciplines, was the development of geophysics, the physics of the Earth and its environment. When the International Union of Geodesy and Geophysics was founded in 1919, geophysics encompassed such disparate fields as geology, geodesy, meteorology, oceanography, seismology, and terrestrial magnetism. Though interdisciplinary in the breadth of the fields of study, geophysics was not interdisciplinary in the integration of the knowledge bases into a coherent whole.

The weapons of World War II, such as the atomic bomb, demonstrated the need for the collaboration of various scientific disciplines. This led to the creation in 1946 of interdisciplinary projects, such as the U.S. Air Force’s Cambridge Research Center Geophysics Research Directorate and the Air Force Cambridge Research Laboratories. This interdisciplinary spirit was boosted from 1957 to 1958, when the International Geophysical Year encouraged interdisciplinary collaboration on subjects such as climatology. The creation in 1970 of the National Oceanic and Atmospheric Administration (NOAA), integrating oceanographic and meteorological studies, was in recognition of the growing need for interdisciplinary science in the study of climate. The National Aeronautics and Space Administration (NASA) followed suit and orbited satellites designed to enhance these interdisciplinary studies by creating an Earth system science.

Interdisciplinary Collaboration

This new emphasis on scientific interdisciplinarianism was demonstrated with the 1977 founding of the journal Climatic Change. This end of knowledge fragmentation and the increased collaboration among disparate fields helped fuel the growth of climatology as a scientific discipline. System interrelatedness was obvious by the mid-1970s, and the symbiosis of meteorology, mathematics, computer science, geophysics, chemistry, biology, and other relevant sciences evolved into an all-encompassing discipline under the academic rubric of Earth sciences. This systems emphasis and interdisciplinary collaboration, augmented by advances in computer technology, expanded climatology from a restrictive, predominantly statistically-based descriptive applied climatology, to include a physical-mathematical modeling discipline with predictive global capability. The International Geosphere-Biosphere Program (IGBP), founded in 1986 and based at the Royal Swedish Academy of Sciences, sought to bring international interdisciplinary cooperation to the study of the global environment.

An important result of this system-based analysis was that the old concept of a normal climatic period gave way to the idea that the climate is dynamic and always changing. During the 1960s, J. Murray Mitchell, Jr., a climatologist with various federal agencies and then with NOAA, asserted that human (anthropogenic) actions influence climate positively and negatively and warned that the negative human influence was apparent in what he determined to be statistically significant global warming. Though it was initially unclear to Mitchell if human atmospheric pollution, particularly carbon dioxide (CO2), might lead to drastic global warming or cooling, it was clear to him that this pollution was radically affecting the global climate and that technological and sociological intervention were necessary to avert a disaster. By the mid-1970s, Mitchell and other scientists became convinced that the real danger was global warning, and not global warming.

The history of climatology was dominated by the global warming debate during the last 30 years of the 20th century. By the beginning of the 21st century, climatology was dominated by computer modeling, and by the assumption that the proper way to understand global warming, as well as regional climates and weather patterns, was by understanding the climate system of the whole planet. This change was reflected in the emergence of the new subdisciplines of climatology: climate change, bioclimatology, paleoclimatology, and applied climatology.