1975-85: GCMs Mature

In this decade, more modeling groups were established. Research programs consisted primarily of improving existing modeling techniques through higher resolution, better parameterizations, and coupling ocean and atmospheric GCMs. Increasingly, modelers began to perform GCM-based experiments. Longer models runs, made possible by faster computers, were an important part of experimental strategies. Increasing political attention to the climate change issue, especially in the United States, raised the visibility of GCMs both inside and outside climate science.

Computer Power

The rapid growth of computer power during this period is illustrated by the following chart of computers used by GFDL.[1]


Time Period

Relative Power

IBM 701



IBM 704



IBM 7090



IBM 7030



CDC 6600






IBM 360/91



IBM 360/195



Texas Instruments X4ASC



Most groups building GCMs either owned or had access to large, fast supercomputers. Greater computer power allowed longer runs, smaller grids, and larger numbers of runs.

Spread of Modeling Capacity

New GCM modeling groups established during this period include:

By the end of this period, European modeling groups -- especially the ECMWF -- had begun to mount a significant challenge to United States dominance in general circulation modeling. Unlike most of the other AGCMs built during the 1970s, the ECMWF's atmospheric GCM was built "from scratch," albeit after careful study of the major existing AGCMs, including variants of the UCLA and GFDL models.[2] Its performance was improved through a continuous cycle of testing and redesign, to the point that today ECMWF medium-range forecasts are considered the benchmark for world weather forecasting.

NCAR Community Climate Model

In the latter part of the 1970s, the National Center for Atmospheric Research gradually abandoned the Kasahara/Washington model. In its place, NCAR developed a Community Climate Model (CCM), intended to serve not only modelers working at NCAR, but the large constituency of affiliated universities associated with NCAR's parent organization, the University Corporation for Atmospheric Research. The Community Climate Model was initially based on the Australian Numerical Meteorological Research Center model and an early version of the ECMWF model. It also incorporated elements of the GFDL models.

The NCAR CCM series of models was especially important because of the relatively large community of researchers who were able to use it. Versions of the model were adopted by a number of other groups in the late 1980s.

Modeling Innovations and Experiments

This decade was marked by steady improvement in existing techniques, rather than major innovation. Increasingly sophisticated and computationally efficient schemes were developed for:

Climate Politics

In this decade, the possibility of global warming became a policy issue within scientific agencies both in the United States and internationally. Studies were conducted by the National Academy of Sciences, the Council on Environmental Quality, the World Meteorological Organization, and others. Congressional hearings called for action, and funding for climate research grew steadily. In 1985, at Villach, Austria, an influential climate science conference recommended policy studies of climate change mitigation techniques, including international treaties.

In the early 1980s, the effects of smoke and dust from a superpower nuclear exchange were tested with climate models, leading to the issue of "nuclear winter."
[3] Action on the ozone depletion issue -- sparked by observations of an Antarctic ozone "hole" -- produced the Montreal Protocol on the Ozone Layer in 1985. Transboundary pollution problems, notably acid rain, were also high on the political agenda. All of these raised public awareness of global atmospheric problems, but the issue of climate change did not achieve the status of mass politics until about 1988.

Top of page | Introduction | Back to 1965-75 | View AGCM Family Tree


[1] Geophysical Fluid Dynamics Laboratory, Geophyscial Fluid Dynamics Laboratory: Activities- FY80, Plans- FY81 (Princeton, NJ: U.S. Department of Commerce, 1981).

[1] ECMWF Research Department, ECMWF Forecast Model Documentation Manual, Internal Report No. 27, Volume 1, ECMWF (1979).

[3] C. Covey, S.H. Schneider, and S.L. Thompson, "Global atmospheric effects of massive smoke injections from a nuclear war: results from general circulation model simulations," Nature 308, no. 5954 (1984): 21-25.

C. Sagan, "Nuclear War and Climatic Catastrophe: Some Policy Implications," Foreign Affairs 62, no. 2 (1983).

S.L. Thompson and S.H. Schneider, "Nuclear Winter Reappraised," Foreign Affairs 64, no. 5 (1986).

Top of page | Introduction | Back to 1965-75 | View AGCM Family Tree