• 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!

• 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?

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.]

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?

Welcome and Aloha!

PACIFIC MARINE PROXY RECORDS

CORRELATIONSSST WITH NINO3 SST

Source: Graham et al. Clim. Change (2007)

Two reference sources on these events yield very similar results: about 35% precip deficit

for 50-100 years

LOW STANDSFROM STINE (1994)

14C dates

MONO LAKE MODERN “NATURAL”

LEVEL

LOW STANDSFROM STINE (1994)

Graham and Hughes (In press).

Source: Graham et al. (2007), Climatic Change< -1.5˚C

PDSI: MCA - POST-MCA DIFFERENCES

PDSI – Cook et al. (2004)Palmyra – Cobb et al. (2003)

COVARIANCE PC #1vs

PALMYRA CORAL δ18O

CCM3 MCA SIMULATION

GCM FORCED WITH INFERREDMCA TROPICAL PACIFIC

SST PATTERN

BASED ON THE PALMYRA & MINDANAO

PROXY RECORDS

40+ ENSEMBLE MEMBERS

IDEALIZED ENSO VARIABILITY

DEC. - MARCH MARCH - JUNE

Simulations by T. Xi and M. Hoerling, NOAA CDC;c.f. Herweijer, Seager, and Cook, 2005

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 1300

Patrick Nunn

Environmental change and cultural response in the Pacific Islands over the last millennium

Simon Haberle