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In order to achieve our goal of improving long-term assessment and predictive capabilities based on knowledge of the integrated components of the Earth system, we plan to continue to address the uncertainties in today's models. In doing so, we expect to provide the nation with benefits in the form of improved understanding that will benefit agriculture, water resources, and other forms of economic activity just as we have seen the benefits of recent investments made in improved short-term weather as well as seasonal and interannual forecasting capabilities.

Thank you very much for this opportunity to participate in this hearing, and I would welcome questions from the subcommittee.


"Our Changing Planet," A report by the SGCR submitted as a supplement to the President's FY 1996 budget.

Statement on "U.S. Global Change Research Program Agency Programs in Global Climate Change Modeling" prepared by Michael MacCracken, April 1995.

Letter from Robert Corell to Peter Guerrero of GAO dated May 22, 1995, and attachment.

Statement on "Earth System Modeling Activities in the United States” prepared by Michael MacCracken, February 1995.

USGCRP Report on "Forum on Global Change Modeling" (USGCRP-95-02).

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U. S. Global Change Research Program
Agency Programs in Global Climate Change Modeling'

Prepared by
Michael C. MacCracken, Director
Coordination Office of the USGCRP
April 1995 (updated from Feb. 1995)


Use of models that represent the Earth system to make projections of future environmental conditions necessarily rests on the foundation of understanding how the Earth system functions now and has functioned in the past. Development of this understanding requires a broad-based research program that includes observations taken at the surface and from space, the assembly of global data sets for driving and testing of model simulations, analysis of results from focused studies designed to improve understanding of important processes and influences, scenarios of the future level and type of socio-economic activities, estimation of the interactions among system components, inventories and records of human-induced factors that force change, and more. These needs are all in addition to the modeling activity itself, which requires: development of quantitatative formulations (i.e., parameterizations) for representing physical, chemical, and biological processes that can be included in models, comparison and testing of the models with observations of current and past climatic behavior, analysis of


This brief note has been prepared at the request of the General Accounting
Office to describe agency modeling programs that focus on the issue of global
climate change. In particular, the GAO request is interested in activities
relating to global three-dimensional modeling in areas such as:
a. testing, verifying, and/or applying global models of the atmosphere,

oceans, and/or land surface (including global chemistry related to
greenhouse forcing and/or vegetation models) and whose focus is on
simulation of global climate, climate variability, and climate change on
time scales of decades to centuries relating to changes in the
concentrations and chemistry of greenhouse gases and aerosols and/or

land surface change due to human activities;
b. simulation of the baseline global climate system (including vegetation)

to which perturbation studies are being compared; c. global simulation of paleoclimates where the purpose is to understand

factors that can help in understanding and identifying climate change

due to human activities; and
d. global verification and model intercomparison studies, including

diagnosis of results from global models and associated comparison
with observations.

simulations and sensitivity studies, and actual application of the models to study of realistic scenarios for the future. The U. S. Global Change Research Program (USGCRP) encompasses this entire set of research activities and uses the understanding and predictive capabilities that have been developed in the investigation of climate change and greenhouse warming, ozone depletion and UV radiation, natural seasonal to interannual fluctuations in the climate, and analysis of the effects of changes in large scale land cover and land use.

The USGCRP combines the research efforts of twelve agencies. Overall, the focused USGCRP interagency budget was approximately $1.44B in FY-94. Of the total USGCRP FY-94 budget, approximately 61% ($883M) supported observing and data management activities, approximately 31% ($456M) supported focused studies of how processes amplify and influence global change, about 4% ($50M) supported integrated modeling and prediction, and about 4% ($55M) supported study of potential consequences and assessment of socio-economic effects. In addition to these focused USGCRP activities, the agencies conduct research activities that are undertaken for primary reasons beyond the impetus of the USGCRP, and are thus not included in these totals. For example, in the area of observations, activities are quite extensive (e.g., operation of U. S. weather satellites), whereas in other areas they are more modest (e.g., modeling of the global climate system).

Because there is considerable synergy with respect to research on the various global environmental issues, it is not possible to precisely allocate budget shares for research among the various global environmental issues; however, most of the research contributes strongly to the understanding of global climate change on decadal to centennial time scales in addition to its contributions to other areas. To be consistent with the GAO request for information, the focus here will be on describing those agency programs for which the primary purpose is to support three-dimensional modeling relating to human-induced perturbations of the climate on time scales of decades to centuries. Note that activities for which the primary purpose is the study of processes and numerical techniques and development of parameterizations to include in global models and programs focused on constructing models primarily to investigate atmospheric chemistry (e.g., stratospheric ozone) are not included in the set of programs considered here.

Agency Areas of Emphasis in Climate Change Modeling

Five agencies support research activities in which full global climate models are being improved, tested, and, in some cases, used, to make projections of the future climate and how it may change. Their efforts are highly synergistic and complementary, with research programs that span modeling needs ranging from integration of parameterizations into full global models to development of more efficient computing methodologies, and from verification of models against current climates to simulation of past and future climates and climatic variability. Given the complexity of the climate system, the importance of the issue being addressed, and the necessary dependence on models because the Earth system cannot be dissected in the laboratory, it is essential that there be a multi-pronged research effort that pursues the range of viable approaches and the range of types of inquiry into Earth system behavior.

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The agencies and their areas of emphasis in climate change modeling are:

1. NOAA, which focuses primarily on seasonal to interannual prediction

and on improving understanding of long-term variability and change.
NOAA's activities include: (a) developing and improving models of
the atmosphere-ocean system, (b) comparing model simulations to
observations and analyses of the processes that are most influential, (c)
simulating the potential climatic effects of increases in greenhouse gas
concentrations, and (d) understanding the confounding effects of
natural climate variations on the detection and attribution of the
effects of human activities on the climate. In addition to modeling
long-term climate change, NOAA has emphasized development of
models capable of predicting the seasonal to interannual fluctuations
that cause rainfall extremes and other similar disruptions to regional
climates; such variations need to be understood in order to provide the
foundation for projecting how climate variability will change in the
future. In addition to its USGCRP research component, which funds
research in the universities, the NOAA Environmental Research
Laboratories provide in-house support for its efforts.

2. NASA, which focuses its modeling effort primarily on enhancing four

dimensional data assimilation in order to enable optimal use of
satellite data and places special emphasis on the role of data from
satellites and other sensors in providing useful information to
improve predictions. In support of climate change modeling, NASA
efforts emphasize: (a) improving understanding of the relative roles of
the various factors that are forcing climate change in the present and
have changed climate in the past, (b) analyzing the global scale effects of
feedback mechanisms that can amplify or moderate climate change,
and (c) developing tools that help integrate together data from satellites
and other sensors into a coherent record of atmospheric behavior.
Research is both in-house at its laboratories and external at universities
and research centers.

3. NSF, which focuses on the seasonal to centennial period (in partnership

with NOAA and DOE) and provision of computer resources for the
research community. Its USGCRP climate change modeling program
emphasizes research on coupling models of the atmosphere, oceans,
and land surface into a single integrated model capable of making long-

term simulations of the dynamics, thermodynamics, biogeochemistry, and hydrology of the global climate system. In addition to this development of the knowledge base for climate change studies, NSF also provides major computer resources for modeling activities. NSF also supports a wide ranging fundamental science research program that underpins the focused climate change modeling program, including especially simulations of climates of the distant past, of natural variations in the present climate, and of the interactions of the various processes and influences in determining the climate. Research is sponsored both in universities and at the National Center for Atmospheric Research.

4. DOE, which focuses on decadal to centennial climate change and

variability, especially as affected by human activities, and on
computational techniques. Its climate change modeling program
emphasizes: (a) assessing the performance of climate models through
an international intercomparison of the ability of models to represent
the recent climate, (b) simulating the effects of carbon dioxide
emissions on the climate, and (c) developing improved global models
by taking advantage of the new generations of highly parallel
computers. These activities are intended to develop the coupled ocean-
atmosphere-land surface models that are needed to make more
accurate climate projections over decades to hundreds of years while
incorporating high resolution and advanced process parameterizations.
The objective is to provide the advanced predictive tools essential to
reducing uncertainties about global climate change. Research is
sponsored in universities, in the laboratories and centers of DOE and
other agencies.

5. EPA, which focuses its modeling research on the chemical and

biospheric interactions that are of very direct concern to EPA's mission. Their research activities emphasize particularly improving the representation of ecosystems and biogeochemistry in global models so that the effects of climate change on the biosphere and of biospheric change on the climate can be projected. The research programs that they sponsor are conducted primarily by scientists at research centers of the other agencies where major modeling activities are carried out.

In addition to the efforts of these five agencies, the USDA supports research focusing on the regional application and interpretation of results from global climate models and the USGS supports research to use global model results in the interpretation of the record of the Earth's climate, which has important implications also for geological resources.

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