1. Ocean Research Priorities Plan Near-Term Priority Abrupt Climate Change and the Atlantic Meridional Overturning Circulation (AMOC) Anticipated Outcomes Enhanced understanding of the MOC system Design a comprehensive MOC observation and monitoring program. New forecasting capabilities Improved ocean models, coupled models, and ocean analyses for their initialization. Characterize the impacts and feedbacks of changes in the MOC on ecosystems, carbon budgets, and regional climate. Abrupt Climate Change and the Atlantic Meridional Overturning Circulation (AMOC) Anticipated Outcomes Enhanced understanding of the MOC system Design a comprehensive MOC observation and monitoring program. New forecasting capabilities Improved ocean models, coupled models, and ocean analyses for their initialization. Characterize the impacts and feedbacks of changes in the MOC on ecosystems, carbon budgets, and regional climate. Linked to CCSP/CVC Abrupt Change Initiative

2. Outline What is it? Urgency Objectives Execution Outcomes

3. What is the Atlantic Meridional Overturning Circulation (AMOC)? The Atlantic Meridional Overturning Circulation (AMOC) is the dominant north- south ocean circulation feature in the Atlantic. The AMOC is the main route for the global ocean heat conveyor belt circulation in the Atlantic. About 80% of the heat from global warming over the past 50 years was absorbed by the ocean. The variability of the AMOC helps regulate the ocean’s heat capacity to slow down the warming of the atmosphere, as well as how the ocean sequesters and redistributes carbon. Large variations of the AMOC impact sea ice, ecosystems, ocean temperatures, and sea level. A major change of the AMOC would significantly alter global climate patterns, such as temperature and precipitation patterns over North America and Europe. AMOC

4. Examples of the Impacts of Decadal Climate Variability in Recent Times History of decade-long droughts and floods in Europe, Asia and North America Decade-long droughts in North American Great Plains in 1890s, 1930s, and 1950s. Societal problems in Brazil due to decade-long droughts. The Sahel droughts in the 1970 -1990s and consequent societal impacts. Decadal droughts in Pakistan and Afghanistan in the 1980s and 1990s and consequent socio-economic-political upheavals, with geopolitical consequences. Decadal-multidecadal variability in numbers of hurricanes and other tropical cyclones. Wetter Drier Normalized index from tree ring data

5. What is the urgency? The recent upswing in Atlantic hurricane activity is linked to changes in the Atlantic ocean resulting from natural and anthropogenic effects. Studies also indicate that such Atlantic changes contribute to drought conditions over the U.S. A firm basis for understanding whether or not this activity will persist or return to normal does not exist. Neither the enhanced hurricane activity nor recent persistent U.S. droughts was anticipated. Are they the forerunners of a rapid change to a new climate state? What would be other impacts such as to coastal and marine ecosystems? Climate science and our observing capability have progressed rapidly and are now ready to be applied towards answering these critical questions. Models indicate that a slowdown of the AMOC is imminent

6. Assessing AMOC Variability: Implications for Rapid Climate Change Objectives: –Understand the mechanisms behind fluctuations of the AMOC. –Develop monitoring and predictions of AMOC changes. –Identify impacts on the ocean, climate, and weather events. Components: –Fundamental Research –Observing and Monitoring the AMOC –Ocean Analyses –Developing Nowcasting Capabilities and Experimental Products –Assessment of Potential Impacts of Rapid AMOC Changes

7. Collaboration: Coordinate University, federal and international initiatives to understand, monitor, and forecast this large-scale ocean phenomena and its potential for global impacts. Leverage and support the broader CCSP priority on “Assessing Abrupt Changes in a Warming World”. Participate in international programs to develop long-term in situ and space-based monitoring systems for the MOC and relevant processes Support experimental decadal predictability studies and establish a national integrated modeling, observation, and prediction capability for the AMOC. Build upon collaboration with international partners [e.g. UK RAPID WATCH], as well as some developing South American partnerships. Assessing AMOC Variability: Implications for Rapid Climate Change

8. An Early Warning System for Abrupt Changes/Decadal Variability The early warning system needs the ARGO array, satellite observation such as altimeters,and specialized ocean arrays WAVE Array “Western Atlantic Variability Experiment” “RAPID WATCH”

9. An Early Warning System for Abrupt Changes/Decadal Variability Model simulations combined with observations are needed to monitor for AMOC changes AMOC collapse - modelObserved snapshot early 1990’s

10. An Early Warning System for Abrupt Changes/Decadal Variability Climate changes are globally synchronized in many paleo-climate proxy records. Models replicate these patterns. Suggestions of predictability…

11. AMOC Program Execution Players NASA Physical Oceanography Program: Satellite data analyses, modeling and observations. NOAA Climate Program Office (CPO) will implement the project through a grants program and direct research at GFDL and AOML. NSF Geosciences Programs: Process research, models and observations. Coordination US CLIVAR Interagency Working Group has been engaged to serve as the coordinating body for an AMOC research program, with NOAA, NSF, and NASA as the main participants. Coordinate with CCSP Research on Abrupt Climate Change Generally agreed to form a “Science Team” to focus on MOC objectives.

12. What will be accomplished? Building on investments agency already made in ocean observing systems and ocean and climate modeling capabilities the following advances are planned by 2012: A routine capability to assess changes to the AMOC will be implemented. A climate history of Atlantic and global ocean changes will be developed for the past 50 years to enable recent changes to be put into a historical context of changes to climate in general. A firmer understanding will be established of the origins and structure of AMOC variability and trends, the implications of these on regional and global climate, and their predictability will be assessed. Working with interagency and international partners an objectively based design will be established for the sustained ocean observing system required for such an early warning system and the economic and social benefits to be derived from this estimated. A prototype early warning system for some possible rapid climate changes will be implemented based on projections of likely future changes out to a decade or more (in partnership with the Administration’s CCSP).