3.

4.

Changes in Ozone, Ultraviolet Radiation, and Atmospheric Chemistry, with the goal of understanding and characterizing the chemical changes in the global atmosphere and their consequences for human well-being.

Changes in Land Cover and in Terrestrial and Aquatic Ecosystems, with the goal of providing a stronger scientific basis for understanding, predicting, assessing, and responding to causes and consequences of changes in terrestrial and aquatic ecosystems resulting from human-induced and natural influences.

Details about progress over the past decade of US/GCRP funded research may be found in "Our Changing Planet" for FY 1997 and FY 1998 which can be provided upon request. These reports are also available on the Internet through http://www.usgcrp.gov/.

The status of the science of climate change is presented in the reports of Working Group 1 of the Intergovernmental Panel on Climate Change (IPCC). The most recent report, “Climate Change 1995, The Science of Climate Change" was published by Cambridge University Press in 1996. Over a thousand scientists from both the U.S. and abroad have been involved in the preparation and review of this important report. In my professional judgment, this report represents the most authoritative assessment of the science of climate change. I will summarize what I conclude from this report and other DOE studies as they pertain to the status of the General Circulation Models (GCMs), the models used to study and predict climate change:

Modeling groups, world-wide, are improving their models at a rapid pace to account for the wealth of new scientific knowledge that has resulted from recent research. Considerable progress has been made in developing a formalism to rigorously test the components of climate models (e.g., atmospheric GCMs, ocean GCMs, land surface models, sea ice models, etc.) that comprise the coupled modeling system. This formalism is being extended to coupled models as well as to the systematic identification of major sources of uncertainty.

For example, given the correct sea-surface temperature, atmospheric GCMs broadly simulate the observed climate. Similarly, ocean GCMs, when "forced" with observed atmospheric conditions, do a good job of reproducing the observed distributions of salinity and sea-surface temperature. The highest resolution, global ocean GCMs, known as "eddy-resolved" models, produce strikingly realistic simulations of the ocean circulation. Coupled climate models that employ this new generation of component models are now producing realistic simulations of the observed climate without the need for corrections, called flux-correction, which was required to overcome climate "drift."

On the other hand, there are large discrepancies between models in their ability to simulate land-surface processes, but these models have improved since 1990 and will continue to improve as data from observational programs become available. Reducing the uncertainties in land-surface modeling is especially important for the estimation of the effects of climate change on the local

and regional level.

Continued progress in model-based climate change prediction ultimately rests on our ability to test and validate the models' predictive skill. This requires the observing systems and data necessary to compare simulations against the real world. The major US/GCRP observational programs are focused on developing the very data sets required to reduce model uncertainties. Additionally, the Global Change Observing System will provide continuous information upon which predictions can be tested and revised.

Another authoritative source of information on the predictive capability of GCMs is the report of the Forum on Global Change Modeling which was published by the US/GCRP in July 1995 (USGCRP Report 95-02). The Forum was organized at the request of the Office of Science and Technology Policy and the General Accounting Office and was chaired by Professor Eric Barron of Pennsylvania State University. The scientific participants included advocates and skeptics on the usefulness of model results to predict and assess global climate change. The forum consensus divided modeling results in three categories: those with a high level of certainty, those that are very probable, and those that are uncertain. The Forum conclusions are in general agreement with the IPCC conclusions described above.

Both the Forum and IPCC agree that climate models are improving. However, both reports also agree that there are still significant uncertainties in GCM predictions and therefore model results can only be couched in probabilistic terms. These uncertainties include:

1.

2.

Incomplete representation of important physical processes in the present models, particularly cloud and aerosol feedback effects and oceanic heat transport;

insufficient computer power to conduct multiple, independent simulations of climate change to thoroughly test the models and produce a statistically significant number of predictions;

4.

theoretical limitations on the predictability of the climate system.

The US/GCRP continues to support major efforts to address and reduce all these uncertainties. In fact, the DOE contributions to the US/GCRP are primarily focused on improving the predictive capability of GCMs. Three such contributions include the CHAMMP program, the Program for Climate Model Diagnosis and Intercomparison (PCMDI), and the Atmospheric Radiation Measurement (ARM) program.

The CHAMMP program has made an important impact on climate modeling by entraining a new community of scientists, many with strong physics backgrounds, who have taken a critical look at many of the assumptions and practices of existing modeling groups and challenged them to make

necessary improvements. An example of this entrainment has been the technical oversight provided to CHAMMP by the JASON scientists. JASON is a prominent group of mostly academic scientists that advise the Federal Government on a variety of scientific problems.

The CHAMMP program has also helped bring advanced climate simulation to the leading edge of computational technology by forging strong collaborations with the high performance computing resources at the DOE weapons laboratories. One such example, at the Los Alamos National Laboratory, is the Parallel Ocean Program (POP), one of the best high resolution global oceans models in existence. We are currently seeking to develop and apply the next generation of scientific supercomputers based on Symmetric Multiprocessor (SMP) Technology to climate change prediction applications.

Another promising new development of our climate change prediction research is the Parallel Climate Model (PCM), among the first of the next generation of high resolution, high performance coupled ocean-atmosphere models. The PCM model employs the atmospheric component of the National Center for Atmospheric Research (NCAR) Community Climate Model, the POP model, and the sea ice model of the Naval Postgraduate School. The PCM effort is led by Dr. Warren Washington at NCAR and is among the few current models that do not use a flux-corrected method and that have nearly eliminated the climate drift problem. Simulations of PCM will be 5-10 times faster than other models at comparable spatial resolution.

Our confidence in the ability of climate models to simulate the current climate and predict climate change from increasing greenhouse gas concentrations has been bolstered by the PCMDI efforts at Lawrence Livermore National Laboratory. Led by Dr. Larry Gates, this program has established atmospheric and coupled ocean-atmosphere model intercomparison projects that produce reference simulations of climate models for comparisons with climate data. Applying rigorous standards of quality assurance and quality control, PCMDI has been universally accepted as the testbed for climate models. PCMDI-led intercomparisons have helped identify the principal areas of modeling uncertainties and defined the process studies needed to reduce these uncertainties.

The ARM program is one process study that was launched as a result of an intercomparison project that demonstrated the need to improve the ways models represent the atmospheric radiative balance, including the role of clouds. With experimental sites in Oklahoma, the North Slope of Alaska, and the Tropical Western Pacific, the ARM program is collecting the data that are critical to how GCMs address the most important uncertainty in climate change prediction, clouds. The ARM program utilizes a variety of ground based remote sensing instrumentation as well as manned and unmanned airborne research platforms. We are also fostering a strong collaboration between the ARM program and the current and future satellites of NASA's Mission to Planet Earth.

The investments in climate modeling research made by DOE and other US/GCRP agencies such as NSF, NOAA, and NASA, as well as by other countries, e.g., the United Kingdom and

Germany, are improving our ability to predict global climate change. More importantly however, the new generation of climate models will start providing reasonably reliable information at regional levels. It is this improved confidence in our future ability to provide regional climate change forecasts that has prompted the US/GCRP to undertake a comprehensive assessment of the regional impacts of climate change in the U.S., and thus fulfill a mandate of the Global Change Act of 1990.

In this testimony I have focused on the science of climate modeling. However, I need to emphasize that our success in deciphering the mysteries of the Earth system relies on the pursuit of many other scientific areas, including the global carbon cycle and ecological processes. The US/GCRP nurtures the strong interdisciplinary research that is necessary and seeks a careful balance between observations, modeling, and process studies.

I am confident that the new generation of climate change prediction models that will be employed for the next round of IPCC scientific assessments will provide more definitive predictions of climate change at both the global and the regional level. In the meantime, I believe that the research results to date do not contradict any of the conclusions of IPCC 1995.

I will be happy to respond to questions.

Ari Patrinos

Dr. Patrinos received a diploma in mechanical and electrical engineering from the National Technical University of Athens and a PhD in mechanical engineering and astronautical sciences from Northwestern University. His research included atmospheric turbulence, computational fluid dynamics, and hydrodynamic stability. After a year on the faculty of the University of Rochester he joined Oak Ridge National Laboratory in 1976 to conduct research on energy-related weather and climate modification and to develop numerical codes for loss-of-coolant (LOC) nuclear accident simulations as well as for river flows and lake circulations.

In 1980, he joined Brookhaven National Laboratory to develop atmospheric chemistry models and to lead field programs on wetfall chemistry. In 1984, he was detailed to EPA and to the National Acid Deposition Assessment Program (NAPAP) staff in Washington, DC. He joined DOE in 1986, restructuring the Department's atmospheric sciences program, and in 1988 led the expansion of DOE's research effort in global environmental change. He was the director of the Atmospheric and Climate Research Division (ACRD) of DOE's Office of Health and Environmental Research (OHER) until 1990. When ACRD was merged with OHER's Ecological Research Division, he became director of the combined Environmental Sciences Division.

From August 1993 until March 1995, Dr. Patrinos was acting as the Associate Director for Health and Environmental Research in the Office of Energy Research; since March 1995 he has been the Associate Director, who oversees the research activities including the DOE human and microbial genome programs, structural biology, nuclear medicine and health effects, global environmental change, and basic research underpinning DOE's environmental restoration effort. Dr. Patrinos represents DOE on several subcommittees of the Committee on Environment and Natural Resources of the National Science and Technology Council. He is a member of the American Society of Mechanical Engineers, the American Geophysical Union, the American Meteorological Society, and the Greek Technical Society.