1. Exploring the spatial patterns of changing surface ocean conditions in the Tropical Atlantic and Pacific Kilbourne, K.H., D. E. Black, J. Nyberg, T. M. Quinn, R. S. Webb, A. Winter

2. Main Points Don’t forget the rest of the tropics. Interactions between the ocean basins can be important Atlantic Perspective on the LIA

3. Questions What is the state of knowledge of Caribbean climate history? How do the spatial patterns tie into the Pacific climate history Are the patterns consistent with known inter-basin connection mechanisms?

4. Earlier work in Tropical Atlantic SST –Centennial resolution –Short records –Indicated cooler conditions during the Maunder Minimum –Some hint of changes in seasonal range Examples: –Keigwin et al., 1996 (Bermuda) –Winter et al., 2000 (Puerto Rico) –Watanabe et al., 2001 (Puerto Rico) –Nyberg et al., 2002 (Puerto Rico)

5. World Ocean Atlas 2001 Annual SST x x

6. Example of Resolution Nyberg et al., 2002 - Artificial Neural Network

7. Hasse-Schramm et al., 2003 Black et al., 2007 Kilbourne et al in process 2007 TemperatureTemperature Higher Lower New SST data: High resolution

8. Centennial-scale Puerto Rico Coral  18 O driven by SST SST proxy SST and SSS proxy

9. Hasse-Schramm et al., 2003 Black et al., 2007 Kilbourne et al in process 2007 TemperatureTemperature Higher Lower Pacific MCA New SST data: High resolution Galapagos P>E All agree 2˚C cooler

10. Local and Regional Surface Temperature Anomalies Track Hemispheric Anomalies

12. World Ocean Atlas 2001 Annual SST x x x x

13. Hasse-Schramm et al., 2003 Black et al., 2007 Kilbourne et al in process 2007 TemperatureTemperature Higher Lower Pacific MCA Seasonal Perspective

14. LPTA 2004 - 1751E1P ~1673 - 1446 Monthly Coral Data

15. Seasonal Range in  18 O No large changes in seasonality evident from the  18 O Coral  18 O = f( SST and  18 Ow) so a seasonally resolved independent temperature proxy is needed to confirm.

16. Atlantic -Pacific Linkages

17. Atmospheric Link Zhang and Delworth (2005) –Modeled a shut down of THC –Resulted in Anomalous Hadley Circulation –Cooling in tropical Atlantic => SLP –Across the Isthmus, SLP too

18. Atmospheric Link Chunzai Wang (2006) “An overlooked feature of tropical climate: Inter-Pacific-Atlantic variability” –Examined the effects of SST gradient between Pacific and Atlantic equatorial regions –Resulted in anomalous Walker Circulation –Positive feedback –Far field effects in Pacific South America ColdWarm Wind Anomalies Colder Convergence Amplification of Pacific Walker Anomalies

19. Coral Data from NCDC

20. Difference ~1750-1800 from ~1900-1950 Coral data available from NCDC

21. Summary of Tropical LIA Spatial Pattern Cooler Caribbean and Gulf of Mexico Warmer and Drier in Southwestern Pacific Potentially warmer/wetter in cold Tongue Enhanced SST Gradient between Atlantic and Pacific

22. Could This Mechanism Be Working During the LIA? What other processes could be at work? South America ColdWarm Wind Anomalies Colder Convergence Amplification of Pacific Walker Anomalies

23. Suggestion The way to really get at processes and mechanisms is data assimilation Despite best efforts, data are often chosen because they fit a story Need an objective way to handle the errors in proxies and dating - cost functions

24. Selected Previous work in the Caribbean Keigwin et al., 1996 (Bermuda) – ~1˚C cooler during the Little Ice Age Winter et al., 2000 (Puerto Rico) –Coral  18 O in 5-year segments –2-3˚C cooler during Maunder Minimum –The  18 O is a combined signal of SST and  18 Ow Watanabe et al., 2001 (Puerto Rico) –Paired Mg/Ca and  18 O –Found 2-3˚cooler during 1699-1705 (really ~1499-1505) –Hiatus visible in core x-ray - dating off by ~200 years Nyberg et al., 2002 (Puerto Rico) –Foraminiferal abundances - artificial neural network –Increased seasonal SST range ~1600-1400