PROGRAM TITLE:  	Earth System History (ESH)
ACTIVITY STREAM:  	Process, Model, Data
SCIENCE ELEMENT:	Earth System History

 NATIONAL SCIENCE FOUNDATION

SCIENTIFIC MERIT:   The goal of ESH research is to understand the natural 
long-term variability of the climate system preserved in the geologic record.  
To assess future climate change we must understand the full range of the 
Earth's variability and how the interlinked systems of ice, ocean, atmosphere, 
continents and biosphere respond to different conditions.  Data observations 
and process studies of past conditions provide two unique elements not 
attainable by other methods: (1) Verification and sensitivity testing of climate 
models.  Models intended to predict future change must be capable of 
reproducing accurately conditions known to have occurred in the past; if not, 
policymakers cannot rely on their predictions.  Researchers are testing models 
by applying them to periods when the Earth's climate was warmer or colder 
than the modern world, with greenhouse gases different from present levels. 
Key questions include: Can extreme warm climates occur without increase of 
greenhouse gases?  Conversely, does increase in these gases always produce 
global warming and if so can the amount be quantified?  Can models 
accurately reproduce rapid changes known to have occurred?  (2) Data from 
geologic time-series reveal previously unknown relationships and processes.  
Examples include the finding that atmospheric concentrations of greenhouse 
gases can change by 30% in less than one thousand years, and evidence that 
unstable oscillations in ice sheets and ocean circulation can occur in less than 
one hundred years.  Current studies are directed toward addressing such 
questions as: Which places on the planet are most sensitive, and which are 
likely to respond first to any change?  Where is carbon stored during times of 
low atmospheric concentrations and how is it transferred back to the 
atmosphere?

All of these topics and many others are actively being investigated by 
individuals and groups of researchers.  Tools and techniques are well 
developed; the principal constraint is the acquisition of appropriate material 
such as cores from ice sheets and sediments of lakes and oceans.  Some of 
these questions will be answered within the next five years; others will take 
longer.

STAKEHOLDERS:   Findings from ESH studies contribute to science elements 
of Biogeochemical Dynamics and Ecological Systems.  ESH is closely linked to 
NOAA's Climate and Global Change Program, especially programs on 
Paleoclimatology and on Atlantic Climate Change; it is also linked to the 
USGS PRISM project. Internationally ESH is the major U.S. contribution to 
PAGES, a core project of the IGBP.

POLICY RELEVANCE:    ESH research contributes principally to the 
commitment on Climate Change and Natural Variability, with implications 
for Biodiversity, Forests and Deforestation, and Desertification.  A central 
policy topic is the relative impact of human-induced change compared with 
the degree of natural change. Results of the model verification will help 
policymakers to determine reliability of model predictions; findings on 
ecosystem responses, such as the potential to re-populate an environment, 
also have policy implications.

PROGRAM CONTACTS:	
Herman Zimmerman,  Climate Dynamics Program Director 
Bilal Haq, Geophysics Program Director
John Maccini, Geology and Paleontology Program Director