PROGRAM TITLE: 	 	Early Detection of the Greenhouse Signature 
ACTIVITY STREAMS: 	Observations/Data Mgmt., Assessments 
SCIENCE ELEMENTS: 	Climate and Hydrologic Systems; Biogeochemical 
			Dynamics; Ecological Systems and Dynamics; Earth 
			System History 
BUDGET LINE ITEM: 	EPA, ORD, Stratospheric Modification, 
Global Climate

U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT

SCIENTIFIC MERIT: Model predictions from general circulation models 
(GCMs) provide the principal means of anticipating the magnitude and 
timing of global climate change from increasing greenhouse gases (GHGs). 
The problem remains to complement efforts to improve modeling with 
methods to experimentally confirm the greenhouse effect. 

The increase in annual average global surface temperature over the 
past century is consistent both with GCM predictions of GHG warming and 
natural climate fluctuations. GHG concentrations may force additional 
warming in the next decade. Increased understanding of the role of aerosols 
in offsetting GHG warming, and better modeling of portions of the dynamic 
climate system should permit more precise delineation of the greenhouse 
signature. Observations would markedly alter the policy debate from the 
likelihood of change, to the questions of how much and when. 

This new project initiates an effort to foster design of observational 
programs targeted specifically at early detection of the greenhouse signature.
The design would consider existing and planned monitoring programs, and examine
possible modifications to maximize signal-to-noise ratios. The planned work 
would also estimate the time required after monitoring implementation 
to answer whether human-induced global climate change is occurring. 

The approach is focused on each of the four major earth systems which 
can rapidly respond to climate change: atmosphere, cryosphere, oceans, 
and terrestrial biosphere. Modeling and indicator sensitivity studies would 
be used to identify unique GHG warming responses. Observational programs 
capable of detecting the predicted signals will be designed and evaluated. 
Full interaction among the four research groups will be stimulated, and 
results will be vetted among international groups including IGBP and WMO.

STAKEHOLDERS: Interagency linkages are being developed. Discussions 
with research institutes are underway, as are discussions with the IGBP and 
WMO. This project requires close interactions across all CEES work groups.

POLICY RELEVANCE: Contributes to the 1995 and subsequent IPCC 
Assessments as well as the following major milestones in the U.S. GCRP:

OBSERVING SYSTEMS AND DATA MANAGEMENT; Ecological Systems, 
1996-2000 Mile- stone: Data sharing coordinated among long-term networks; 
Global Systems, 1996-2000 Milestone: Operational system for global climate 
information products implemented;

ASSESSMENT; 1991-1995 Milestone: First IPCC and WMO/UNEP 
assessments of global changes completed; 1996-2000 Milestone: Integrated 
international assessmentsÊof global change continued.

PROGRAM CONTACT: Lee Mulkey, U.S. EPA, 960 College Station Road, 
Athens, GA 30605-2720, 706/546-3129