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date: 03 December 2022

The Role of the American Meteorological Society in Climate Sciencefree

The Role of the American Meteorological Society in Climate Sciencefree

  • Keith L. SeitterKeith L. SeitterAmerican Meteorological Society

Summary

The American Meteorological Society (AMS) is one of the premier international scientific societies covering the atmospheric and related sciences and has been for over 100 years. Throughout its history, the AMS has organized scientific meetings and conferences that have supported the discussion and debate of topics in climate science (as well as other topics in the atmospheric and related sciences) and has used its publications to disseminate the scientific results of those working in climate science. AMS publications have been especially important in providing information to the entire scientific community on major global research programs. Since 1995, AMS has collaborated with the National Oceanic and Atmospheric Administration to publish an annual “State of the Climate” report that chronicles Earth’s changing climate, and since 2011, the AMS has published an annual series that assesses extreme events from a climate perspective.

The position of the AMS on scientific and policy issues is provided by periodic statements issued by the AMS, and many AMS statements have addressed issues related to climate, including the human influence on climate change. While the official AMS position on climate change has been consistent with the scientific consensus, the AMS has provided a platform for challenges to the consensus, as long as those challenges meet an adequate threshold of scientific rigor, which fosters debate that advances the science further. The AMS also works to reduce the politicization of climate science and has consistently maintained a strong position on the integrity of science. Throughout, the AMS has served as a trusted resource for policymakers and the public on climate science and aspects of global change.

Subjects

  • History of Climate Science

The American Meteorological Society as a Forum for the Advancement of the Science of the Climate System

Since its founding in 1919, the American Meteorological Society (AMS) has played a central role in the development of climate science. The original mission statement of the AMS was: “The advancement and diffusion of knowledge of meteorology, including climatology, and the development of its application to public health, agriculture, engineering, transportation by land and inland waterways, navigation of the air and oceans, and other forms of industry and commerce” (AMS, 1920a). That early support for climatology and the research efforts that would evolve into what we now call climate science was almost certainly strengthened by the fact that the AMS was established under the leadership of Charles Franklin Brooks, who was director of the Blue Hill Observatory, south of Boston, and a leader in promoting high quality climate observations (more on the history of the AMS as an organization is available in Seitter et al. [2019]).

Early AMS support for climatology included the dissemination of climatological data, but more importantly it also involved providing a forum for discussions of research on all aspects of the Earth system. The pages of the Bulletin of the American Meteorological Society (BAMS), as well as scientific lectures and meetings organized by the AMS (which were usually extensively summarized in BAMS after the fact), provided a means to connect those engaged in the growing scientific discipline of meteorology (in which climate science was fully embedded at the time). New observations and new ideas to explain what was being observed are chronicled in BAMS over those early years and it provides a record of the AMS fostering a fledgling science on its way toward a rigorous physical science.

There are other scientific societies that played roles in supporting the advancement of climate science, both in the United States and internationally, and many of the elements of the support outlined here within the AMS were mirrored by similar activities in those other organizations. Within the United States the AMS has served as the primary organization devoted specifically to the atmospheric and related sciences, and the AMS has taken leadership roles internationally as well, so in that context its activities have been especially important.

As the discipline of meteorology expanded and became more grounded in the physical sciences, its ability to serve society directly grew, as well. A greater understanding of the processes driving atmospheric circulations and their attendant precipitation patterns led to ever more skillful weather forecasts. That same growing understanding allowed those studying the Earth’s climate system to broaden from climatology as a set of records of climate variables toward climate science as an explanatory (and eventually predictive) science.

Throughout the growth and development of climate science as a discipline independent from traditional meteorology rather than subsumed within it, the AMS provided support for the community through scientific meetings and a growing suite of technical research journals. Many of the seminal papers in climate science were published in AMS journals and the AMS Journal of Climate is recognized as one of the leading journals in the field.

As the impacts of human activities began becoming clear the AMS was, and continues to be, a leader in providing scientific evidence to policymakers and the broader society. The annual publication of the State of the Climate and the “Explaining Extreme Events from a Climate Perspective” series provide trustworthy input to the policy discussion, as do AMS statements covering climate and other global change issues. As climate change became more politicized, the AMS has been a venue for meaningful discussion and debate and has encouraged dissenting points of view as long as they are grounded in rigorous science. In all components, the AMS has maintained a continuing defense of the integrity of science and the scientific process.

The Early Years

The early issues of the Bulletin of the American Meteorological Society (BAMS) included summaries of the research articles included in the journal Monthly Weather Review (MWR), which at the time was a publication of the U.S. Weather Bureau. Many of the brief research articles published in MWR in the early 1900s covered topics that would be categorized as climate science today. A review of the MWR summaries published in just the first few issues of BAMS gives a sense of the climate-related efforts of the time. Among others, they included articles on the variation of solar radiation by geographic area in the United States, weather factors affecting the yield of winter wheat in Ohio, analysis of the Australian drought, and a comparison of snowboard versus rain gauge can measurements of snowfall.

Figure 1 provides the preliminary program for the AMS meeting organized for April 1920. This one meeting agenda gives a good sense of the breadth of topics considered to fall under the purview of the AMS scientific umbrella. This was a period of rapid growth of knowledge about the Earth system and the broad interdisciplinary discussions in these early AMS meetings must have been incredibly engaging.

Figure 1. Program for the April 22, 1920 meeting of the American Meteorological Society.

Source: Reprinted from Bulletin of the American Meteorological Society, 1, 29 (1920b).

In those early days of BAMS, it was common for an issue published after a scientific meeting to contain a fascinating summary of the meeting presentations, sometimes including transcripts of the question-and-answer periods following presentations. There was an almost folksy style in BAMS for its first decade or two, with single paragraph news items that might report on a single interesting observation or offer an unverified hypothesis for the physical process behind some phenomena. Reading those early issues (all of which have been scanned and are freely available on the AMS’s website) gives one a glimpse into a small but vibrant community of scientists and serious enthusiasts sharing their love of learning how the atmosphere works.

With the science so young and with still so much to be learned, almost every new observation or analysis of past data yielded an interesting piece of the puzzle and BAMS was an effective avenue to share these new insights with the broader community. It was also a place for the emerging science to gain a sense of self and develop internal guidelines for ethical practice in a science that has always been about service to the public. In that context, the short entries in the pages of BAMS included discussion of new services being offered but also concerns about those practicing outside the ethical boundaries. As just one example, the May 1920 issue of BAMS included a piece decrying charlatans selling services as “rainmakers” and noting that since their contracts were often written in forms that had them paid if a certain amount of rain fell over a certain time period, they could count on natural variability to meet that threshold for some contracts but had no liability in the other cases (Brooks, 1920).

The role of the AMS in fostering advances in climatology and climate science is clearly evident in a review of the papers presented at AMS meetings over the Society’s first few years. In December 1920, a year after the inaugural meeting of the AMS, the Society held a major meeting in Chicago. As typical in these early meetings, the papers presented covered a wide array of topics, but it is striking how many papers concerned topics that would occupy climate scientists for decades. Papers covered aspects ensuring high-quality and consistent observations for the climatic record, including proper thermometer sheltering, measuring evaporation rates, siting considerations relative to topography and geographic features, and the reduction of long observational records to homogeneity in light of siting issues (AMS, 1921a). Several papers looked at the possible influence of solar variability on climate parameters and there were a few very interesting papers dealing with the relationship between climate and health (AMS, 1921b).

At the AMS meeting of December 1921, the presidential address by Robert De C. Ward, who was completing his two-year term as the first AMS president, reviewed the current state of the science of climatology at the time and what he saw as trends (Ward, 1922). Ward emphasized the potential for advances in climatology to provide benefit to society in a variety of ways and applauded the efforts of the scientific community to push the boundaries of the science. He stressed the need for meteorologists and climatologists to share the responsibility of ensuring that meteorological observations were of adequate quality to contribute meaningfully to the climatological record. He also advocated for an increased focus on not just climatological averages but also a deeper recognition of the variability of weather that contributed to those averages and the ranges of extremes within that variability.

BAMS often carried summaries of papers presented at meetings other than those sponsored by the AMS directly and BAMS also included many summaries of papers appearing in non-AMS publications. There was a serious effort to allow all readers of BAMS to participate in the science to the fullest extent possible, knowing that most would not have the means to attend these various meetings or subscribe to journals that might only occasionally have a paper related to weather or climate.

Early AMS meetings were often collocated with those of other societies, such as the American Association for the Advancement of Science (AAAS). How climates change was an area of study by those active in the AMS in the early years and the AMS provided avenues for its discussion and debate. The December 1924 meeting of AAAS included a symposium on ancient climates and BAMS published summaries of several key papers from that event (AMS, 1925). Papers included several possible explanations for the ice ages, including the role of topographic features and ocean extent, volcanic eruptions triggering cooler years that induced feedback mechanisms, and several possible terrestrial impacts related to solar variability.

These early years set the stage for AMS meetings to be an important venue for sharing research results, as well as speculations, on the science of climate. They established the AMS as having a foundational role in placing climatology on a firmer scientific basis and on the emergence of what would become the discipline of climate science.

Introducing Conference Series

While convening scientific meetings was a core activity of the American Meteorological Society (AMS) from its inception, it was not until after World War II that the AMS began convening ongoing series of scientific meetings devoted to specific subdisciplines within the atmospheric and related sciences. These specialized meetings allowed those researchers working in specific areas of the science to gather and discuss and debate their latest findings. There is a long history in science of gatherings of researchers focused on specific research areas leading to spirited discussion that spurs rapid scientific advances, and in the mid-20th century the AMS created the organizational structures needed to facilitate a growth of specialty conference series in support of the subdisciplines under the Society’s umbrella (Seitter et al., 2019).

The first discipline-specific conference series was for radar meteorology and began in 1947 and the first devoted to topics in climate was the Conference on Applied Climatology series that began in 1961 (Seitter et al., 2019). The number of disciplinary conference series grew rapidly over the next two decades, with over 30 being regularly organized annually or biennially by 1980. Many of these dealt with research areas of relevance to climate and climate change, such as conference series on atmospheric chemistry, radiation, air–sea interactions, the urban environment, and many others. While the Conference on Applied Climatology series continued, in 1981 a separate Conference on Climate Variations (whose title changed later to Conference on Climate Variability and Change) series was initiated to focus more directly on issues related to global change.

Symposia on specific phenomena were also organized and these sometimes grew into ongoing series. The Symposium on the Prediction of the Madden–Julian Oscillation is an example, with the first symposium organized to be part of the 2013 AMS Annual Meeting being such a success that the symposium became a regular feature of AMS Annual Meetings from that year forward. In other cases, phenomena-specific sessions became regular features of larger conferences, such as the sessions on the El Niño–Southern Oscillation (ENSO) which are featured each year as part of the Conference on Climate Variability and Change. Sessions on ENSO and seasonal predictability and forecasts are common in other AMS conferences, as well.

As the number of researchers working in the atmospheric-related sciences grew, these disciplinary (and subdisciplinary) conferences would be seen as increasingly valuable among those working in specific research areas. Small, focused conferences allow communities of practice to develop and offer venues for intense scientific debate on research at the leading edge of the topics covered in that conference. It is not unusual for arguments at a meeting to spur new research efforts toward resolution at a meeting a year or two later—pushing the scientific frontier forward through the effort. These disciplinary conferences are organized through volunteer program committees of the scientists who attend the meeting, with AMS staff providing infrastructure so that the scientists planning the meeting can focus on the meeting content without worrying about logistics, maximizing the potential for advancement of the science through the meeting.

AMS conferences typically include strong participation from international scientists and many of the conference series organize an occasional conference to take place outside the United States, typically in collaboration with an organization in the host country (often the meteorological society of that country). The AMS has a longstanding formal agreement with the European Meteorological Society outlining cooperation and collaboration, and similar agreements with several national societies, such as the Royal Meteorological Society, Indian Meteorological Society, Australian Meteorological and Oceanographic Society, Chinese Meteorological Society, and others. With support from federal agencies, the AMS has often provided direct travel support for scientists from the developing world, and students or early career scientists from any country, to attend conferences and workshops to further support international collaboration.

It is worth noting that scientific conferences also provide venues for meetings of smaller working groups (both formal and informal) that can take advantage of the fact that most members of that working group will be at the scientific meeting. The AMS Annual Meeting has, for decades, included a large number of side meetings along these lines that have contributed to an array of advances in climate science, including the planning of major field campaigns whose results were later published in AMS journals (see “Dissemination of Results from Major Global Programs”).

AMS Journals

Peer-reviewed scientific journals play a foundational role in supporting science. American Meteorological Society (AMS) journals, as well as the peer-reviewed article portion of the Bulletin of the American Meteorological Society (BAMS), which represents a journal in its own right separate from the membership news portion of BAMS, have been leaders in the atmospheric and related sciences for many decades. A complete history of the evolution of AMS publications is provided by Seitter et al. (2019). BAMS played a critical early role supporting research and application related to the climate system. The journal Monthly Weather Review (MWR), which began in 1872 as a publication of the U.S. Army Signal Corps, was also a key publication that provided an outlet for observations and research on meteorology and climatology in the early 20th century and early issues of BAMS routinely summarized articles that had appeared in MWR. The AMS launched the Journal of Meteorology in 1944, which began a slow but steady growth in discipline-specific journals over the subsequent decades (Seitter et al., 2019). In 1974, MWR, which was then a publication of the National Oceanic and Atmospheric Administration (NOAA), was transferred from the U.S. government to the AMS.

MWR emerged as one of the key journals for important papers in climate science (Schultz, 2022; Schultz & Potter, 2022). The foundational efforts in creating computer simulation models of the atmosphere that could be used for operational weather forecasting were published in MWR, so it became the natural journal to publish the original groundbreaking work in climate modeling (Manabe, 1969; Manabe et al., 1965; Smagorinsky, 1963; Smagorinsky et al., 1965). Observational studies have always been a core element of MWR and have included major contributions on important climate-scale phenomena, such as El Niño–Southern Oscillation (Bjerknes, 1969; Horel & Wallace, 1981; Rasmusson & Carpenter, 1983) and the teleconnections patterns identified for the Northern Hemisphere (Wallace & Gutzler, 1981).

As climate science expanded, coverage of it in AMS journals grew as well, with an increasing number of climate science papers being published in MWR and the Journal of the Atmospheric Sciences (which replaced the Journal of Meteorology in 1962) and special continuing series appearing in the journals, such as the quarterly Seasonal Climate Summary in MWR (Pielke, 1982). The AMS also expanded the scope of the Journal of Applied Meteorology (JAM), which had been published since 1962, to include papers in basic and applied research and renamed it to the Journal of Climate and Applied Meteorology (JCAM) (Hecht & Bergman, 1983). There was a continuing growth of climate science in the 1980s, including research into seasonal climate-scale phenomena, especially following the intense El Niño of 1982 and the launch of the Tropical Ocean Global Atmosphere (TOGA) program in 1985 (McPhaden et al., 2010). This resulted in the AMS creating the Journal of Climate in 1988 to consolidate climate papers into a single journal (Hecht, 1988), with JCAM reverting to JAM at the same time. By 2000, the Journal of Climate had grown to be the largest of the ten journals published by the AMS at the time.

The AMS has always tried to ensure the broadest dissemination of the research published in its journals. In the late 1990s, the AMS scanned all back issues of its journals and posted the content online, increasing the amount available as open access until, in 2012, all content older than 12 months was made freely available (Seitter et al., 2019). In the early 1990s, with funding from several U.S. federal agencies, the AMS began providing its journals in print to research and educational institutions throughout the developing world. After online delivery became viable, the AMS transitioned to providing the journals to developing world scientists through major international programs such as Research4Life. The AMS also provides support for researchers from the developing world so that they can cover the author charges to publish their work in AMS journals.

There were, of course, thousands of papers on climate published in AMS journals and BAMS over the past century, but it is noteworthy that many of the papers now considered to be groundbreaking or seminal appeared in AMS publications. Independent assessments of the most influential papers in climate science (see, e.g., Forster, 2021), typically cite Manabe and Wetherald (1967), which appeared in the AMS Journal of the Atmospheric Sciences, as one of the critical contributions to climate science, with the later contribution by Held and Soden (2006), which appeared in the Journal of Climate, as also worthy of mention (Pidcock, 2015).

A particularly prescient paper appearing in AMS journals is Schneider (1975), which reviews the various estimates on the impact of doubling CO2 that had been published at that time (and in doing so, includes many of the landmark papers in climate science up to that point). The paper concludes by stating that the “important and perplexing dilemma posed by the present inability of climate theory and modeling to offer much more than an order-of-magnitude estimate of the climatic effects of increased CO2 is that the seriousness of potential climatic risks of continued use (or social risks of abandoned use) of fossil fuels to the year 2000 and beyond range from negligible to extreme . . .” (Schneider, 1975). The paper then notes that since the impacts on the high end of the estimates are enormous and possibly irreversible, it might be wise to err on the conservative side and limit fossil fuel use in the future, while preparing for the inevitable “adjustments” that will be needed as our climate changes.

Dissemination of Results from Major Global Programs

American Meteorological Society (AMS) journals played an important role, of course, in providing outlets for research results coming out of major national and international observation and research programs. Beyond that, however, the AMS was also instrumental in keeping the broader community informed on the creation of, and major results from, these regional and global programs.

A particularly clear example was a running series of articles in the Bulletin of the American Meteorological Society (BAMS) on the Global Atmospheric Research Programme (GARP) that ran under the banner “GARP Topics” for many years. The series began in 1969 with an overview of GARP that was presented, interestingly, as a set of questions and answers (Reed, 1969). The regular series of articles began a few months later with a paper on atmospheric predictability by Lorenz (1969) and continued with high-quality contributions for years, concluding with article number 85 of the series in 1986 (Paegle, 1986). The series included articles covering the design of and results from the First GARP Global Experiment (FGGE, 1972) as well as articles on the important GARP Atlantic Tropical Experiment (GATE), with the first article in that series being an extensive description of the experiment design (International and Scientific Management Group for GATE, 1974).

In the 1990s, BAMS presented the “AMS Continuing Series on Global Change” with the stated purpose of providing a “series of articles reporting on the U.S. Global Change Research Program and international global change activities with particular emphasis on the World Climate Research Program, the International Geosphere-Biosphere Program, and the Human Dimensions of Global Environmental Change Program.” This series included significant climate science papers, such as Held (1993) and Karl et al. (1993).

BAMS articles on major global research programs not only provided descriptions of the program and results but also provided valuable information on how data would be archived and made available to the research community (see, e.g., International and Scientific Management Group for GATE [1974] or Webster and Lukas [1992]). While it is commonplace now for articles to include links to websites containing data, prior to the 21st century there were often significant protocols associated with obtaining experimental data sets. In an effort to support the broadest possible dissemination and use of a 40-year reanalysis data set completed by the National Centers for Environmental Prediction (NCEP) and the National Center for Atmospheric Research (NCAR) in 1996 (Kalnay et al., 1996), the AMS worked with NCEP to mass-produce a CD-ROM with the data set and deliver it with every issue of BAMS (see figure 2).

Figure 2. CD-ROM of 40-year reanalysis data set mailed with every issue of the March 1996 Bulletin of the American Meteorological Society.

Source: Photo by K. Seitter.

These few examples, out of many possible ones, provide a sense of how the AMS has helped the climate science community (and, of course, the broader atmospheric and related sciences community) share information on major research programs. In many cases, a BAMS article serves as the primary citable description of a new research program (for example, the Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment [TOGA COARE] program [Webster & Lukas, 1992]). In others, articles in BAMS provide updates to the community on longstanding programs to build greater awareness of their impact on climate science and/or alert the community to new capabilities, such as when Mather and Voyles (2013) reviewed 20 years of the Atmospheric Radiation Measurement (ARM) Program while also describing recently expanded capabilities in the program. BAMS contributions also provide valuable analyses of global climate programs from both scientific and political points of view (e.g., White, 1982).

State of the Climate Reports

In 1991, the National Oceanic and Atmospheric Administration (NOAA) began creating an annual “Climate Assessment” that provided a summary of key climate variables for the prior year. Starting with the Climate Assessment of 1995 (Halpert et al., 1996), the report began being published as a supplement to the Bulletin of the American Meteorological Society (BAMS), with the AMS overseeing an independent peer review of the report prior to publication. The transition to a BAMS publication served several important functions. Having the AMS carry out an independent peer review of the report prior to publication in one of the highest ranked publications serving the atmospheric and related sciences raised its scientific credibility and independence from NOAA. This took the report out of the realm of potentially being viewed as “gray literature” (despite the extensive work always done by NOAA prior to publication to ensure its accuracy), and therefore made it more valuable to the scientific community and policymakers alike. Its publication in BAMS also ensured broader dissemination worldwide. This was especially true in the years before the dissemination of large documents over the internet was commonplace but remains so even when the report can be posted on NOAA web pages in addition to being included in BAMS. AMS publication also ensures that each report will be archived in perpetuity as part of the scholarly record and easily recovered by future scholars.

With the assessment covering 2002, the report began being published under the title “State of the Climate” to better reflect the nature of the report to that point, which was thus described (Waple & Lawrimore, 2003):

It contains analyses of the global climate system for 2002 including significant events and their impacts, and atmospheric dynamics that have influenced weather and climate over the year. The report also seeks to place the climate of 2002 in historical perspective with analysis of trends and variability in temperature, precipitation, and climate forcing during the period of instrumental record. Proxy climate records are also included to aid in understanding the Earth's climate prior to the systematic collection of instrumental climate observations.

With continued and growing emphasis on the policy issues surrounding climate change, and especially humanity’s role in causing it, the value and importance of this report as a fact-based annual “health report” grew commensurately. The report has expanded its scope and the number of “essential climate variables” covered by it over the years, with the 2020 assessment coming in at 475 pages (Blunden & Boyer, 2021), compared to the early assessments that were typically a few dozen pages.

Explaining Extreme Events Reports

The annual State of the Climate reports provide extensive information on the global state of the climate and chronicle major weather and climate events, but they do not try to assess what role climate change may have had in producing those events. With policymakers and others increasingly looking to the scientific community to provide answers on whether extreme events were “caused” by climate change, the climate science community began working to develop tools to answer those attribution questions. With the release of “Explaining extreme events of 2011 from a climate perspective,” the American Meteorological Society (AMS) began publishing an annual series in the Bulletin of the American Meteorological Society (BAMS) analyzing specific extreme events from the prior year in an attempt to determine what role our changing climate may have played (Peterson et al., 2012). That first report chose six events and used those to highlight a variety of methodological approaches to attribution, recognizing the challenges of determining the role climate change may have played for any individual event but hoping to spur additional discussion and research on this topic.

The Explaining Extreme Events reports were quickly picked up as newsworthy by media outlets and their release is often accompanied by one or more media events. By the tenth report, covering events from 2020, the report had grown to include 18 articles and comprise 117 pages (Herring et al., 2022). Through this series, the AMS has helped push the boundaries of attribution science and solidify it as a legitimate subdiscipline within climate science.

Statements

The American Meteorological Society (AMS) began releasing “policy statements” presenting the position of the Society on scientific issues in 1957. AMS statements are adopted by the AMS Council on behalf of the entire membership and are considered the official position of the Society on an issue. As noted in the first explicit description of AMS statements (AMS, 1962a):

The Council of the American Meteorological Society recognizes and accepts an obligation to call to public attention issues of public policy which relate to meteorology and to provide to the general public factual information and, when appropriate, estimates of the likely effects of alternative courses of action so that an informed and knowledgeable citizenry can participate in policy decisions.

Statements quickly became an important component of the Society’s support for the scientific community and its influence on public policy related to environmental issues and that has continued through the subsequent decades. By the 1970s, the term “policy statement” was replaced with just “statement” to reflect the fact that many of the statements released were informational summaries of the current state of the science (on, e.g., hurricane or tornado forecasting) without explicit policy recommendations. Statements related to global environmental issues increased in frequency over time, becoming a major focus of attention as the human influence on global change became clearer.

The first AMS statement in 1957 dealt specifically with the emerging science of weather modification through cloud seeding. In 1962, the AMS released the “Statement on implications of the control of weather and climate” (AMS, 1962b). This statement was quite remarkable in seeing the role computer simulations would play in assessing the impact of human-caused changes in weather and climate. After summarizing early experimentation in cloud seeding (referencing the 1957 statement on weather modification), the 1962 statement noted the recent “demonstration that physical laws governing atmospheric motions can be cast in mathematical form suitable for processing on high speed electronic computers, to predict the future state of the atmosphere.” The statement goes on to say (AMS, 1962b):

The second development, application of numerical methods of forecasting by means of high speed computers, together with use of model experiments in studying atmospheric processes, gives promise that it will some day become possible to predict with accuracy the short and long term effects of artificial interference with normal atmospheric processes. This ability to predict accurately what would happen in the absence of modification attempts, and what would happen if they are applied, is an essential prerequisite to any rational attempt at weather control.

While cast in the context of deliberate control of weather or climate in this statement, the essence of the role of numerical simulation in understanding the impacts of human intervention mirrors the approach used in climate science today to assess human impacts on climate.

The prospect of direct human influence on climate was introduced in the 1967 “Statement on weather and climate modification” (AMS, 1968). Despite the inclusion of climate in the title, the statement primarily focused on weather modification, covering the state of the art at that time (discussing the potential of precipitation enhancement through cloud seeding, hail suppression, fog dispersal, and even hurricane suppression). While localized impacts on climate variables by manmade structures were discussed, deliberate human intervention to change a region’s climate was treated as “still in the realm of scientific speculation.” It is noteworthy that the statement urged caution, recognizing that there are risks of unintended consequences for any program aimed at modifying the weather or climate, and it also encouraged international collaboration in any large-scale program.

The first AMS statement that addressed a global climate issue directly was the “Policy statement of the American Meteorological Society on potential atmospheric impact of chlorofluorocarbons emissions” released in September 1976 (AMS, 1976). The statement provides an excellent summary of the issues associated with chlorofluorocarbons (CFCs), especially Freons F-11 and F-12, and their possible role in the destruction of stratospheric ozone (it also mentions the potential impacts on stratospheric ozone from other human activities, such as supersonic transports and the space shuttle). Given that the potential for stratospheric ozone depletion due to CFCs was, at this time, completely theoretical, the statement included an unusually clear discussion on the uncertainties in the risks that were outlined and the possibility of taking unneeded action in error. The statement called for increased scientific research on several fronts, including enacting legislation to ensure federal authority to regulate CFCs, the creation of international frameworks to address this as a global issue, and actions to prepare to rapidly enact restrictions on CFCs as possibly indicated by further research. Interestingly, the statement also called for explicit labeling requirements on products that used CFCs as propellants to allow consumers to make informed choices.

In 1983, the AMS released a statement in the wake of climate science research on “nuclear winter” with “Consequences of nuclear war on global environment” (AMS, 1984). This brief statement read (in its entirety):

Recognizing the inevitable widespread, devastating consequences of nuclear war by direct explosive effects, and effects propagated through the atmosphere to the entire globe that could cause the destruction of the biological base that sustains human life, the Council of American Meteorological Society calls on the nations of the world to take whatever steps are necessary, such as the adoption of appropriate treaties, to prevent the use of nuclear weapons and avoid nuclear war.

Beginning in 1988, the AMS, often in concert with other organizations, began producing “transition documents” aimed at the new administration following the U.S. presidential election. These documents, which were often approved as formal AMS statements to carry the weight of the Society, provided recommendations for government priorities in the areas of weather and climate. The first such document, created in partnership with the University Corporation for Atmospheric Research, was “The changing atmosphere—Challenges and opportunities” and it was the first AMS statement that explicitly addressed the growing body of evidence that humans were responsible for global warming (AMS, 1988). This extensive document summarized research results projecting human-caused warming of 3°F–10°F over the subsequent 50 years, and outlined the expected impacts (sea-level rise, higher frequency and intensity of hurricanes, more floods and droughts, changes in weather patterns, and the associated impacts on agriculture and other activities). The reduction of stratospheric ozone due to CFCs was also a prominent concern in the statement. The statement called for increased emphasis on research in weather and climate in general but also laid out a framework for a coordinated federal climate change research program. The U.S. Global Change Research Program, established by Presidential Initiative in 1989 and mandated by Congress in 1990, closely followed the framework provided in this statement.

The AMS addressed climate change as a singular issue in 1990 with the release of “Policy statement of the American Meteorological Society on global climate change” (AMS, 1991a). This statement mostly provided a “state of the science” summary of climate change research and expected impacts—setting the stage for a series of AMS information statements on climate change over the following decades. It highlighted a number of areas where much more research was needed on physical processes and where improvements in the then-current generation of climate models were most needed. In that sense, it was nearly equally important in its roles as a document for the public on the current state of knowledge, a call for policymakers to invest more in key areas of atmospheric and related sciences research, and a roadmap for those in the community on where emphasis is most needed.

As climate science progressed rapidly in the 1990s, there were calls for the AMS to issue an updated statement on climate change to replace the statement published in 1991. This period also saw, however, an increasing level of diversity of opinions on how best to address climate change, which became more politically influenced with each passing year, and often translated into challenges to various aspects of the science and a focus on areas of uncertainty. It was, therefore, very difficult to reach levels of consensus that allowed for an AMS statement that truly represented the community (McPherson & Hallgren, 2003). Continued effort toward a statement that focused on the large areas of agreement within the climate science community and that also acknowledged where further research was required to reduce uncertainties resulted in the statement entitled “Climate change research: Issues for the atmospheric and related sciences” (AMS, 2003).

By the 2000s, AMS statements routinely had their time “in force” set by the AMS Council at the time of adoption, ranging from three to six years, but averaging five years. Given the difficulty in reaching closure on the 2003 climate statement, updates to the statement were often begun well before the current statement was set to expire. Through the diligence of volunteers on drafting committees and AMS Council members, subsequent statements titled simply “Climate change” were adopted and released in 2007, 2012, and 2019 (AMS, 2007, 2012, 2019). Throughout, the AMS climate change statement has often been held up as an exemplar for a concise summary that was grounded in the best available peer-reviewed literature.

In response to increasing concerns within the scientific community on possible unintended consequences from trying to deliberately manipulate the climate system to ameliorate the impacts of climate (referred to as geoengineering), the AMS released in 2009 the statement on “Geoengineering the climate system” (AMS, 2009). This policy statement summarized a number of geoengineering approaches and potential risks and concluded with recommendations for more research along with efforts to create effective and transparent international policy approaches for moving forward if viable candidates are found. The statement was updated in 2013 (AMS, 2013) with relatively minor changes. A more significant replacement was release in 2022 under the new title “Climate intervention” (AMS, 2022).

Many other statements on issues related to climate science have been (and continue to be) produced through the AMS process, covering scientific topics such as drought, atmospheric ozone, atmospheric chemistry, and others, but also addressing climate services, the role of climate science in our educational system, and more (see “Statements of the AMS in force”).

This brief and very selective history of AMS statements gives a sense of how the AMS played an essential role in bringing together consensus positions of the community for a number of purposes. AMS statements provide trustworthy information to the public on the state of the science, highlight issues needing attention by policymakers and/or members of the scientific community, and often provide a roadmap for the most effective actions to make progress on them. The statement creation process itself complements other activities within the community that bring the science toward consensus positions (such as scientific meetings and journals).

Scientific Challenges to the Consensus View of Human Impact on Climate

As concerns increased about the possibility that humans were causing the Earth to warm following landmark papers such as Manabe and Wetherald (1967), more researchers turned their attention to the issue. While consensus was emerging on some level of warming, the magnitude of that warming was open for debate, with some being convinced that human influence was not likely to be large enough to have consequential impacts. Through the 1970s, large numbers of studies were published by the American Meteorological Society (AMS), and other scientific publishers, with independent estimates of the temperature rise accompanying a doubling of CO2. The peer-reviewed literature of the time has many examples of articles or comment/reply sequences with one research team criticizing the estimates of other research groups and exposing errors in the other’s analysis as the community argued its way toward some level of consensus understanding (see, as just one example, Crane [1981] and references therein).

By 1990 there was consensus within the climate science community on the role of humans in warming the Earth, and policymakers were beginning to debate possible actions to limit future warming. In its role of fostering useful discussion on these issues, the AMS helped expose the scientific community to the policy debate. This was done through articles and essays published in the Bulletin of the American Meteorological Society (BAMS), such as the extensive analysis and perspective piece by Schneider (1990), and through featured presentations at AMS meetings, with two notable examples being major talks by Congressman George Brown at the 1990 AMS Annual Meeting (AMS, 1990) and then-Senator Al Gore at the 1991 Annual Meeting (AMS, 1991b), both of which were reproduced in their entirety in BAMS to make them available for the entire community.

As the discussion of policy solutions to human-caused climate change began to be more common, those seeking to oppose specific policies often challenged the scientific consensus. These so-called climate skeptics mostly focused on existing areas of uncertainty in the science to argue that policy solutions should not be implemented until and unless the science is on a much firmer foundation. A summary of the status of the scientific consensus as of 1991, with rebuttals to common climate skeptic arguments (some of which are still raised over 30 years later), is provided by Kellogg (1991). Even as the consensus on the human impacts on climate became stronger through the 1990s and early 2000s, as reflected in Intergovernmental Panel on Climate Change (IPCC) reports through the period (IPCC, 1995, 2001, 2007), there were still challenges to that consensus from members of the scientific community. While the official position of the AMS, as provided by AMS statements on climate change, was consistent with the IPCC summaries, the AMS viewed its role as continuing to provide a platform for challenges and debate—as long as they met an adequate threshold of scientific rigor. Thus, the AMS journals and BAMS played a central role in allowing these issues to be raised, discussed, and largely resolved. A few key examples illustrate this.

The “Iris” Hypothesis

Lindzen et al. (2001) suggested that changes in increasing sea surface temperatures in the tropics would result in less cirrus generation, which would allow more infrared radiation to be emitted to space. In their calculations, this negative feedback was significant and would be sufficient to cancel the positive feedbacks that dominated the results of climate models and led to the range of projected warming reported in the IPCC reports. Lindzen et al. likened this feedback mechanism to an adaptive iris that “opened or closed” to control outgoing longwave radiation in response to changes in surface temperature (similar to the eye’s iris opening or closing in response to light levels). If correct, the climate sensitivity shown in the climate models of the time was significantly exaggerated.

The Lindzen et al. paper in BAMS quickly generated a flurry of new research by climate scientists and those new results were presented at AMS meetings and in AMS (and some other) publications. A number of papers indicated that additional analysis showed there was not a negative feedback iris effect as hypothesized by Lindzen et al., and in fact, these studies indicated that the effect, to the extent it existed, represented a weak positive feedback on climate rather than a strong negative one (Chambers et al., 2002; Fu et al., 2002; Hartmann & Michelsen, 2002; Lin et al., 2002a). Some aspects of the analysis techniques used by Lindzen et al. were also questioned (Harrison, 2002) and responded to by Lindzen and colleagues (Bell et al., 2002).

The scientific debate continued between those who felt the observations and modeling data did not support the negative feedback of the iris hypothesis and Lindzen and colleagues (Chou & Lindzen, 2005; Chou et al., 2002; Lin et al., 2002b, 2004, 2005). Many additional, and useful, studies of climate sensitivity, and especially the role of clouds in the radiative balance, were conducted to look at the possible iris hypothesis as a feedback mechanism. Even 20 years later, studies on the radiative effects of cirrus in the tropical atmosphere were explicitly addressing the iris hypothesis and its potential role in the earth’s energy balance (Sokol & Hartmann, 2022).

This example illustrates well the role of the AMS (and other scientific publishers like it) in advancing climate science. The original paper by Lindzen et al. (2001) presented a provocative idea that directly challenged established consensus on climate sensitivity. By publishing this paper in BAMS, which has a very broad audience across the weather and climate community, the AMS opened up the potential controversy for all to see and quickly spurred additional research meant to address it. The debate followed the rigorous protocols established in peer-reviewed literature. While the hypothesis did not unseat the consensus view of climate sensitivity, it has illuminated connections between tropical cirrus cloud cover and surface temperature that are still being investigated and there is little doubt that the resulting controversies improved both climate models and our understanding of the climate system.

Global Warming “Hiatus”

There was an exceptionally strong El Niño in 1998 that contributed to anomalously high global temperatures that year. With that data point and the natural variability of global temperatures over the subsequent decade, the global mean temperature curve appeared to have plateaued, leading those that did not accept the science of human-caused global warming to declare that global warming had stopped. By 2013, the 15-year trend of surface temperatures was significantly smaller than the decades prior to 1998, and many felt it could no longer be attributed solely to natural variability. A special thematic box was devoted to the hiatus in the IPCC AR5 report (IPCC, 2013). (There were some in the community who lamented the adoption of the term “hiatus” or “pause” for this period of slower warming, feeling that it played into the hands of those seeking to downplay the impacts of climate change and/or its human causes [Lewandosky et al., 2016]).

As the hiatus progressed beyond about 2010, the climate science community began devoting increasing energy toward understanding the reason for this prolonged decrease in the rate of warming. By the time the 2013 IPCC AR5 report was released, many research teams were actively trying to model the half century leading up to and including the hiatus period to better understand its causes (see, e.g., Kay et al. [2015] and Meehl et al. [2014] and references therein). AMS journals and BAMS had their share of the output of this research, but papers were appearing across the many journals that serve the atmospheric sciences.

AMS scientific meetings played an important role in this case. The 27th Conference on Climate Variability and Change, held as part of the 95th AMS Annual Meeting in January 2015 in Phoenix, Arizona, included three oral sessions and one poster session titled “Global warming hiatus” over a two-day period. The papers presented and intense discussions over the course of this meeting and subsequent AMS conferences have been instrumental in helping the community to debate this issue. How to characterize this period of slower warming, as well as possible causes for it, continues to be an area of controversy. A good summary of the understanding of the hiatus is provided by Wei et al. (2022). After 2017, the global mean surface temperature returned to warming rates comparable to those preceding the hiatus years.

Climate Change Becomes More Politicized

From the first evidence of human influence causing a warming climate, it was clear that solutions would involve significant changes to the way we generate and use energy, with potential disruption to major economic sectors. Those facing these potential disruptions, especially those in the fossil fuel industry and the many others in related arenas, began working to avoid or delay policy solutions to climate change and maintain the status quo. This was most easily accomplished by questioning or denying the scientific evidence of human causes of climate change. Thus, climate scientists increasingly found themselves in the unfamiliar territory of political rather than scientific debate.

The American Meteorological Society (AMS) began taking on a role of actively defending the integrity of science and the scientific process while also striving to retain its apolitical and strictly nonpartisan position as an organization of science. The situation was nuanced because even as the climate science community reached a strong consensus that the Earth was warming and that humans were the primary cause of that warming, there were large uncertainties in several aspects of the argument and a lack of clarity in some potential feedback mechanisms that could only be resolved if subjected to the normal level of scientific debate (such as the “iris” hypothesis). But now, given high levels of politicization, that scientific debate was not confined to a room full of scientists at a conference or the pages of the technical journal read only by those immersed in the subdiscipline (though both of those happened, as well, in the meetings and journals of the AMS and other organizations). Now, these scientific disagreements became much more public, and often legitimate scientific challenges were coopted and distorted toward political ends. Websites and blogs emerged that all purported to present the science of climate change, but many presented misinformation on long-debunked contrarian views wrapped in the veil of being legitimate science, while others tried to combat that misinformation with legitimate science. Climate scientists found themselves dealing with media attention and many found themselves in the uncomfortable position of being the subject of personal attacks by the media and public simply because some did not want to accept their research (Schneider, 2009).

With the increased levels of media attention coming from the high stakes associated with climate change impacts, every major climate science research result ran the risk of being given outsized attention, especially if it supported a political policy position or provided counter evidence to one. Rather than the normal process of publication in a peer-reviewed journal leading to additional research by the community to either validate or challenge the original result over time, there was an increased risk that the original publication would receive media attention and be held high by whatever group had a position it supported, only to see any subsequent study that challenged or refuted it being championed in the media by groups on another side of the issue. This media amplification of what is normally healthy and necessary scientific debate toward consensus on the science is not helpful for policymakers or the public.

While actively providing venues for healthy scientific debate, the AMS has also tried to address the unhealthy politicization and premature media attention on these issues. Through the Bulletin of the American Meteorological Society (BAMS), in addition to at scientific meetings, the AMS has provided venues for uncomfortable conversations around the politicization of science. An example of this is a paper by Curry et al. (2006) that discusses the impacts of media and online attention on the intense scientific debate over the impact of global warming on hurricane frequency and intensity. Building on a theme of how to deal with uncertainty, Curry and Webster (2011a) later challenged aspects of the conclusions reached in the fourth Intergovernmental Panel on Climate Change Assessment Report (IPCC, 2007). Given the potential impact of this challenge, the AMS published the original paper, a rebuttal (Hegerl et al., 2011), and the reply to the rebuttal (Curry & Webster, 2011b), all in the same issue of BAMS as a set. The AMS has been consistent in providing opportunities for serious questions to be raised and addressed, but its editorial boards have done their best to ensure fair and unbiased peer review that did not accept for publication arguments that lacked scientific rigor.

Supporting the climate science community includes gaining an understanding of why there are so many who do not accept the evidence of human-caused climate change. The AMS contributes to this discussion through its publications, covering how climate change skepticism is influenced by cross-cultural components (Rudiak-Gould, 2013a), the visibility or experience of climate change impacts (Borick & Rabe, 2014; Brugger et al., 2021; Rudiak-Gould, 2013b), and ideological narratives (Lejano, 2019), including skepticism in countries other than the United States (Ceglarz et al., 2018; Wang & Lin, 2018).

A special case of the AMS working to both understand and reduce the levels of skepticism on human-caused climate change is with the community of broadcast meteorologists. By the late 1990s, it was becoming clear that broadcast meteorologists were far more likely to reject the consensus on climate change than the broader meteorological community (Wilson, 2002). The AMS partnered with climate communication researchers to better understand this issue and collaborated on programs specifically targeting broadcast meteorologists to increase their understanding and acceptance of climate science as well as provide them the tools needed to present more on climate change to their public audience (Perkins et al., 2017; Stenhouse et al., 2014; Woods Placky et al., 2016). The result of these efforts was rapidly evolving views among broadcast meteorologists on climate change toward the accepted science (Maibach et al., 2017) and this, in turn, has led to more reporting on climate change to the public by the broadcast meteorology community (Feygina et al., 2020; Timm et al., 2020).

As the politicization of climate science expanded in the 1990s and beyond, the AMS maintained a clear focus on the science and its implications for policy decisions. In 1999, the AMS established a policy program (AMS, 1999) to carry out policy studies, help train scientists to better engage in the policy process, and to provide apolitical and nonpartisan policy-relevant information to policymakers. While the AMS Policy Program scope includes all of the atmospheric and related sciences, global change science and related policy issues have made up a large fraction of its efforts.

The AMS has always maintained a strong position on the integrity of science and with the politicization of the climate change issue, it has been called upon frequently to express that position forcefully. A particularly good example is when the AMS supported climate scientist Ben Santer, who had been publicly attacked by Frederick Seitz in the pages of the Wall Street Journal (AMS, 1996). In the early 2000s, U.S. government scientists, and those working in areas of climate science, in particular, were facing increasing political interference in their attempts to present the results of their research. In 2006, the AMS released the AMS statement on the freedom of scientific expression (AMS, 2006). This statement expressed the AMS position that the “ability of scientists to present their findings to the scientific community, policy makers, the media, and the public without censorship, intimidation, or political interference is imperative.” The statement has been readopted essentially without change every five years since its original release to maintain this as the official position of the Society.

The statement on the freedom of scientific expression has been cited in numerous ways over the years to reinforce the AMS position on scientific integrity and support the scientific process and academic freedom. The AMS has used it to support the freedom of expression of scientists who challenge the consensus on climate change just as forcefully as it has for those who support the consensus view (see, e.g., letters to Congressional committee chairs [AMS, 2015a, 2015b]). There are many other examples of the AMS supporting scientific integrity and defending the scientific process with politicians and other policymakers, especially in the context of climate change, while taking care to also provide scientific information that is policy relevant but not policy prescriptive.

Over a Century of Support for Climate Science

This article has provided an overview of how the American Meteorological Society (AMS) has supported the development and evolution of climate science since the Society’s creation in 1919. In some ways, this article has only managed to scratch the surface and given the truly extensive levels of support that the AMS has provided to the community advancing the science of climate and the effective use of those scientific results for societal benefit over the past century, this article should be viewed as providing representative examples of the forms that support took over the years, rather than as an exhaustive chronicle of all aspects of it.

In celebration of its 100th anniversary, the AMS created the monograph A century of progress in atmospheric and related sciences: Celebrating the American Meteorological Society centennial. Its 27 chapters cover all the major disciplines considered to fall under the AMS umbrella “to review 100 years of progress in fundamental areas of research and to present a vision of the grand challenges in these areas of research in the coming decades” (McFarquar & Rauber, 2019). There are chapters in this monograph specific to climate science, but given the importance of nearly all aspects of the atmospheric and related sciences to developing a more complete understanding of how our climate system operates (from numerical simulation to cloud physics to so many others), virtually every chapter is relevant to the climate science story. This monograph complements this article by providing a sense of what was being covered scientifically in AMS (and other) journals throughout this period and discussed and debated in all those AMS (and other) scientific meetings.

Implicit in this entire discussion is that the AMS is a member society made up of those working in the atmospheric and related sciences. So, the support the AMS has provided over the years for climate science is a reflection of this community collectively deciding how best such an organization can support the members of that community. It reflects the leadership of many hundreds of scientists and practitioners who volunteered their time and energy to help guide the AMS over these many decades and who continue to do so as the AMS looks to the future.

Further Reading

References