1. What do we know about climate patterns during the MWP & LIA
What do we know about climate patterns during the MWP & LIA? How different are they from the 20th Century?
What do we know about socioeconomic changes during that time?
Can a better understanding of climate-society interactions during the MWP-to-LIA epochs help us plan for future (anthropogenic) climate change effects?
Welcome and Aloha!

2. There is a good deal of overlapping proxy and model data consistent with a La Niña like tropical Pacific in Medieval times (both in the tropics and the mid-latitudes).
As simulated by models or inferred from proxy records, changes in tropical SST would drive very large climate changes in the Pacific basin.
What would happen to ecosystems and cultures in this region if this pattern were to reoccur?
One goal is to examine the pro’s and cons for cool tropical Pacific during MWP. [Some of the cultural/ecologic changes associated with late Medieval (MWP-LIA transition) are described collectively in Patrick Nunn's papers.]
Welcome and Aloha!

3. PACIFIC MARINE PROXY RECORDS
Source: Graham et al. Clim. Change (2007)
CORRELATIONS
SST WITH NINO3 SST
L. Stott, K. Cobb, Burt Rein, D. J. Kennett

4. Two reference sources on these events yield very similar results: about 35% precip deficit for years
MONO LAKE
MODERN “NATURAL”
LEVEL
14C dates
LOW STANDS
FROM STINE (1994)
LOW STANDS
FROM STINE (1994)
Graham and Hughes (In press).

5. Source: Graham et al. (2007), Climatic Change

6. PDSI: MCA - POST-MCA DIFFERENCES
COVARIANCE PC #1 vs
PALMYRA CORAL δ18O
PDSI – Cook et al. (2004)
Palmyra – Cobb et al. (2003)

7. DEC. - MARCH MARCH - JUNE CCM3 MCA SIMULATION GCM FORCED WITH INFERRED
MCA TROPICAL PACIFIC
SST PATTERN
BASED ON THE
PALMYRA & MINDANAO
PROXY RECORDS
40+ ENSEMBLE MEMBERS
IDEALIZED ENSO VARIABILITY
DEC. - MARCH
Richard Seager Tuesday AM – Herweijer, Seager, Cook 2005
MARCH - JUNE
Simulations by T. Xi and M. Hoerling, NOAA CDC;
c.f. Herweijer, Seager, and Cook, 2005

8. Session 1 Paleoenvironmental studies: archives, proxy records, pre-history, and early history of Pacific Island societies
A Shock to the system: Climatic disruption of Pacific Island societies around AD Patrick Nunn
Environmental change and cultural response in the Pacific Islands over the last millennium Simon Haberle