Lester Machta

Lester Machta, founder and director of the Air Resources Laboratory (ARL) of the National Oceanic and Atmospheric Administration (NOAA), died of leukemia in Washington, DC, on 31 August 2001. As director of ARL, he was known in the scientific community for his innovative work in such diverse areas as transport of radioactive materials, the increase in greenhouse gases, ozone depletion, and other problems that required an understanding of both meteorology and chemistry.

Machta was born on 17 February 1919 in Brooklyn, New York. He went to Brooklyn College at age 16 and received a BS in mathematics in 1939. With some meteorological graduate training behind him, he began his career as part of an effort at the start of World War II to prepare hundreds of officers to serve as forecasters in locations all over the world. At that time, meteorology and the practical need to forecast weather for armed services operations were in their infancy. Many wartime forecasters remember Machta’s lectures at Army and Army Air Corps training centers in Chanute Field, Illinois, and Grand Rapids, Michigan.

On returning to civilian life, Machta completed an MS in meteorology at New York University in 1946 and a ScD in meteorology at MIT in 1948. His doctoral thesis, “A Study of the Observed Deviations from the Geostrophic Wind,” was prepared under the direction of James Austin. In that same year, Harry Wexler, head of US Weather Bureau research, selected Machta to lead a special projects section—which later was called ARL—whose main purpose was to address meteorological and environmental aspects of postwar nuclear activities.

With the end of World War II and the dropping of the atomic bomb on Japan, a new conflict began—the cold war. To the surprise of most people, the Soviets tested their first atomic bomb in 1949, which resulted in an intensive US effort to understand where the bomb was tested, what its yield was, and where the winds transported the radioactive material. Machta participated from the beginning using meteorological analysis to try to understand these questions. Even today, much of his work is still classified. Following the development of the hydrogen bomb, both the USSR and the US continued testing in the atmosphere. The well-known Nevada and Bikini tests throughout the 1950s and into the 1960s were a part of this effort. ARL assisted in this testing by providing information on transport of the fallout, which eventually encircled the world. At that time, Machta proposed that the radioactive materials could be used as tracers to understand weather systems. Eventually, because of human health concerns, the atmospheric testing was banned in 1963. However, because countries continue testing and producing nuclear weapons to this day, Machta worked on this subject until his death.

Although radioactive material in the atmosphere was a major concern during the 1960s, it was soon realized that humankind was affecting the environment in more subtle ways. Machta had an admirable gift for identifying issues—for example, the continuous increase in carbon dioxide—that would seriously impact the environment and the climate. Through the pioneering work of David Keeling, CO₂ was being measured at Mauna Loa and on the South Pole. Machta played a critical role in the early 1970s, however, taking over the operation and maintenance of the Mauna Loa Observatory, which was on the verge of being closed due to funding shortfalls. He was instrumental in establishing, in 1971, the geophysical monitoring for climate change program (now in the Climate Monitoring and Diagnostics Laboratory/NOAA) long before climate change became a household term. Besides saving Mauna Loa, he established new global observatories in Barrow, Alaska, and American Samoa. These global stations, in addition to the South Pole station, and another 18 observatories around the world continue to provide scientific measurements for an understanding of global climate change.

Machta also deserves recognition for his work in the area of stratospheric ozone. Measurement of total column ozone goes back to the 1930s with the development of the Dobson spectrophotometer. This instrument measures the amount of ultraviolet (UV) radiation absorbed by ozone in the stratosphere and, using different pairs of wavelengths, can determine the amount of ozone in a column above the observer. A network of Dobsons was established during the International Geophysical Year (1957–58) and continues to take measurements to this day. At ARL in 1971, Machta, who realized the importance of such measurements, established a unit that would not only measure total column ozone around the world but also ensure the calibration of the Dobson spectrophotometers. Thus, through his foresight, a measurement system was well in place by the 1970s, when the question of chlorofluorcarbons and their effect on the depletion of the stratospheric ozone layer was raised.

Those who have known Machta were fascinated by the breadth of his many scientific interests. ARL, with which he was associated for almost 50 years, reflected this diversity. Besides ARL headquarters in Silver Spring, Maryland, there are five branches throughout the US. Machta orchestrated these units in a very low-key manner with carefully chosen, competent scientific leaders. Under Machta’s leadership, ARL has contributed to such diverse fields as modeling regional air pollution, measuring UV radiation, developing a network to monitor wet and dry deposition, and understanding the dispersion and diffusion of materials from a source such as a nuclear power plant.

Unquestionably, Machta was on the forefront of environmental science for many years. His colleagues have many memories of his quiet nature, which would not bend to pressure to bypass the science. Machta expressed his concern for others in an understated way, exemplified by his always insisting on leaving an elevator last, even in the presence of much younger men—which often resulted in a humorous “after you, Gaston” standoff—and standing aside in a circle of friends to let an approaching party— no matter how junior or unknown— join the discussion. He was not one to show anger even when it would seem appropriate. On meeting this well-known laboratory director and scientist, junior colleagues, who might have expected to find a less accessible person, were surprised by his gentle nature. Machta’s colleagues and friends have been enriched by working with him and will miss his guidance and patient understanding.