Home ->  About the U.S. Climate Change Science Program -> Overview of U.S. Research on Climate and Global Change -> From "Discovery" to "Comparative Analysis" -> Scientific Inquiry

Search

US Climate Change Science Program
Updated 11 October, 2003

Scientific Inquiry
 

 

Over the past decade, the United States has supported long-term studies, research into basic environmental processes, the development of models, and cooperative international field campaigns and assessments. With these resources, the agencies participating  in the U.S. Global Change Research Program (USGCRP) have assembled a comprehensive and interdisciplinary collaboration that has facilitated scientific discovery. The program has sponsored research that has revealed and addressed many of the complex interactions and consequences of climate and other environmental systems.

Scientists have started to assemble information on the complex relationships between natural variability and human activities that could contribute to change. U.S. researchers are pursuing fundamental insights about how the climate and Earth system function, insights that are incorporated into advanced models throughout the world. Among the returns from our Nation's investment are the following:  

Ocean WavesIn and over the oceans, USGCRP missions and programs have:

  • Developed observing systems and models that enabled the successful prediction of the onset of the 1997-1998 El Niño event and the subsequent La Niña, and that identified several other large-scale patterns of natural climate variability (e.g., the Pacific Decadal Oscillation).  

  • Reduced the uncertainty in estimates of rainfall over the tropics by one half, thereby helping to improve short-term weather prediction and management of fresh water globally.  
  • Measured winds at the ocean surface to improve short-term weather prediction and global tracking of major hurricanes and tropical storms.  
  • Produced ocean color maps that document the daily uptake of carbon by ocean biomass, thereby helping to improve estimates of the amount of carbon dioxide removed from the atmosphere.  

In the atmosphere, USGCRP programs have:

  • Continued measurements of concentrations of both ozone and ozone-depleting substances and led international assessments of the estimated recovery time of the Antarctic ozone hole.  

  • Provided quantitative estimates of how much changes in atmospheric concentrations of carbon dioxide, methane, nitrous oxide, and other greenhouse gases are altering the Earth's natural greenhouse effect, and have demonstrated the significant impact of anthropogenically-derived aerosols on the radiative budget of the Earth-atmosphere system.  
  • Yielded new insights into interactions of how changes in aerosol concentrations can affect cloud processes, supporting continuing improvements in the climate models.  

Aerial view of forest and lakes

On and over the land surface, USGCRP-supported researchers have:

  •  Produced the first ever satellite-derived assessments of global forest cover, documenting large-scale changes in land cover and land use that are important to carbon storage, climate change, biodiversity, regional water resources, food supply, and human health.    

  • Conducted field experiments to help understand the role of vegetation on Earth in removing carbon dioxide from the atmosphere and in regulating the hydrological cycle.  

  • Studied the interactions of increased CO2 concentrations with other environmental processes such as nitrogen deposition.  

In investigations of the Earth's long-term climate history, USGCRP supported researchers have:

  • Contributed to significant progress in reconstructing the history of the Earth's climate using surrogate (or proxy) records derived from ice cores, tree rings, pollen, coastal coral samples, and ocean and lake sediment analysis, among other paleoclimatic data.

   The Alps

This information is vital to accurately placing 20th and 21st century climate in historical context, evaluating the significance of future changes in climate, and analyzing uncertainties in projections of climate change in order to focus future research.  

Over the ice caps, USGCRP-supported researchers have:

  • Determined the thinning and thickening rates for the Greenland ice sheet.  

  • Provided the first detailed radar mosaic of Antarctica (in conjunction with the Canadian Space Agency and RADARSAT International).  
  • Provided daily observations of the polar regions from space.  

Satellite view of Greenland

All of this information will be crucial to reducing uncertainties regarding the ice-albedo feedback and the future rate and magnitude of changes to these important systems.  

As the USGCRP and Climate Change Research Initiative (CCRI) look to the future, improving projections of climate variability and change and reducing other significant global change uncertainties will require significant advances in knowledge of the physical, biological, and chemical processes that influence the Earth system. A number of key uncertainties will need to be resolved.

In a report commissioned by the Bush Administration, Climate Change Science: An Analysis of Some Key Questions, the National Research Council (NRC, 2001) reviewed and evaluated the comprehensive climate change assessment produced by the Intergovernmental Panel on Climate Change (IPCC, 2001) and made a number of recommendations about research needs. At the most fundamental level, the NRC report indicated the need to better understand the causes of warming. The report stated, "The changes observed over the last several decades are likely mostly due to human activities, but we cannot rule out that some significant part of these changes are also a reflection of natural variability."  

The NRC report identified the highest priority areas where additional research is needed to advance understanding of climate change:  

Making progress in reducing the large uncertainties in projections of future climate will require addressing a number of fundamental scientific questions relating to the buildup of greenhouse gases in the atmosphere and the behavior of the climate system. Issues that need to be addressed include 

  1. the future usage of fossil fuels,

  2. the future emissions of methane,

  3. the fraction of the future fossil-fuel carbon that will remain in the atmosphere and provide radiative forcing versus exchange with the oceans or net exchange with the land biosphere,

  4. the feedbacks in the climate system that determine both the magnitude of the change and the rate of energy uptake by the oceans, which together determine the magnitude and time history of the temperature increases for a given radiative forcing,

  5. details of the regional and local climate change consequent to an overall level of global climate change,

  6. the nature and causes of the natural variability of climate and its interactions with forced changes, and

  7. the direct and indirect effects of the changing distributions of aerosols.

Maintaining a vigorous, ongoing program of basic research, funded and managed independently of the climate assessment activity, will be crucial for narrowing these uncertainties. 

In addition, the research enterprise dealing with environmental change and the interactions of human society with the environment must be enhanced. This includes support of

  1. interdisciplinary research that couples physical, chemical, biological, and human systems,

  2. an improved capability of integrating scientific knowledge, including its uncertainty, into effective decision support systems, and

  3. an ability to conduct research at the regional or sectoral level that promotes analysis of the the response of human and natural systems to multiple stresses. 

An effective strategy for advancing the goal of understanding climate change also will require

  1. a global observing system in support of long-term climate monitoring and prediction;

  2. concentration on large-scale modeling through increased, dedicated supercomputing and human resources, and

  3. efforts to ensure that climate research is supported and managed to ensure innovation, effectiveness, and efficiency.

The USGCRP and CCRI will focus resources on resolving these and additional uncertainties that need to be addressed to improve understanding of the causes and trajectory of global environmental change.  


 

US Climate Change Science Program, Suite 250, 1717 Pennsylvania Ave, NW, Washington, DC 20006. Tel: +1 202 223 6262. Fax: +1 202 223 3065. Email: . Web: www.climatescience.gov. Webmaster:
US Climate Change Science Program Home Page