Patrick D. Nunn Professor of Oceanic Geoscience The University of the South Pacific

NOAA/IPRC Workshop onClimatic Changes in the Last 1500 Years:

Their Impacts on Pacific Islands, East-West Center, 13th November 2007

A Shock to the System:Climatic Disruption of Pacific Island

Societies around AD 1300

Patrick D. Nunn

Professor of Oceanic Geoscience

The University of the South Pacific

Climate, Environment and Society

• Climatic change produces environmental change.

Channelled scablands, NW USA

Climate, Environment and Society

• Climatic change produces environmental change.

• Both climatic and environmental changes can profoundly affect human societies. Fiji floods, 2004 [courtesy Fiji Times]

Climatic Influences on Environments:insights from high-resolution data series

Source: van de Plassche et al. (2003 [Geology]Solar irradiance (14C) and sea-level change at Farm River Marsh, NE USA

Climatic Influences on Environments:an empirical study from the Pacific

Source: Razjigaeva et al., 2004 [Palaeo3]Kurile Islands, Northwest Pacific Ocean

Climatic Influences on Human Society: general considerations

• Environmental determinism versus cultural determinism.

• Emerging acceptance of the potential of climatic change to “force” changes in pre-modern human societies.

• Watershed studies

Climatic Influences on Human Society: watershed studies from the Pacific

Direct influence of climate on society

Source: Titanium (precipitation proxy), Cariaco Basin, Venezuela, and its effects on Maya civilization in central America (Haug et al., 2001 [Science])

Climatic Influences on Human Society:watershed studies from the Pacific

Source: William R. DickinsonClimate influence on society through environmental filter

Island societies are good case studies because their societies often register an

amplified response to climate forcing.

• Why?• Relative smallness.• Relative isolation.• Relative homogeneity

of environments and societies.

Necker Island, Hawaii Islands

The Pacific Basin

China

Japan

Russia

Philippines

Indonesia

Papua NewGuinea

Australia

NewZealand

Kiribati

MarshallIslands

CookIslands

Alaska

Hawaii

FrenchPolynesia

EasterIsland

GalapagosIslands

Canada

United States

EastAntarctica

WestAntarctica

Chile

Peru

Panama

IndianOcean

AtlanticOcean

TasmanRise

DrakePassage

180°

0°

Volcanic Pacific Islands

Limestone Pacific Islands

Pacific Island paleoclimate

archives

History of human settlement of the Pacific Islands

EQUATOR New Guinea

Solomon Islands

Marshall Islands

Vanuatu

NewCaledonia

FijiTonga

Tuvalu

?

?

Samoa CookIslands

Marquesas

Easter Islandcolonization AD 690

limit of colonization before 750 BC (2700 BP)

limit of pre-Lapita settlement

limit of colonization before AD 500 (1450 BP)

NewZealand - colonization ~AD 1275?

Panamacolonization byPacific Islanderspre-AD 1513?

Hawaiian Islandscolonization AD 650

FrenchPolynesia

?

Taiwan

Philippines

Japan

China

Australiahuman arrival 40.000 BC?

RussiaCanada

United States

human arrival 40,000 BC?

human arrival 30,000 BC?

human arrival 15,000 BC?

Monte Verdehuman arrival 33,000 BC?

Pikimachayhuman arrival 25,000 BC?

?

Organization of this talk

1. Last-millennium climate change in the Pacific

2. Environmental changes on tropical Pacific Islands during the last millennium

3. Societal changes on tropical Pacific Islands during the last millennium

4. Possible climate forcing of last-millennium environmental and societal change in the tropical Pacific Islands: the AD 1300 Event

Part 1

Last-millennium climate change in the Pacific

Last-millennium climate changes in the Pacific: summary

• Medieval Warm Period (ca. AD 750-1250), comparatively warm dry climate with high sea level.

• AD 1300 Event (ca. AD 1250-1350), rapid cooling, increased precipitation, falling sea level.

• Little Ice Age (ca. AD 1350-1800), comparatively cool climate, higher climate variability (increased El Niño frequency), low sea level.

• Recent Warming (ca. AD 1800-present), warming, reduced climate variability, rising sea level.

-20

-19

-18

-17

-16

-17

-18

-19

-20

-21

-18

-15

-12

1000 1200 1400 1600 1800 2000

Time (Years AD)

Huascarán

Quelccaya

Sajama

Little Ice AgeMedieval Warm Period AD 1300Event

Recentwarming

warmer

cooler

δ

O (

‰)

18

δ

O (

‰)

18

δ

O (

‰)

18

Ice coring – tropical Andes

Thompson et al., 2003 [Climatic Change]

Medieval Warm Period – comparative warmth

Little Ice Age – comparative coolness

Recent Warming - increasing warmth

(transition) AD 1300 Event – cooling

Medieval Warm Period Little Ice AgeAD 1300Event

Recentwarming

900 1100 1300 1500 1700 1900

Time (Years AD)

? ?Steller Lobe, Alaska

Prince William Sound, Alaska

Llewellyn Glacier, Alaska

??Colonel Foster Glacier, Vancouver Island

southern Canadian Rockies (general)

Cordillera Blanca, Peru

Cordillera Central, Chile

Soler Glacier, Patagonia

Kiwa Glacier, Canadian Rockies

Robson Glacier, Canadian Rockies

Cathedral, Pagoda and Siva glaciers, Canada

Sredniaya Avacha, Kamchatka

??Glaciar Lengua, southernmost Andes

Glaciar Frias, Patagonia

Compilation from Nunn (2007) book

22

20

18

16

Pre

cip

itatio

n (

cm)

1 500 1000 1500 2000

Time (Years AD)

extreme low standof Mono Lake

extreme low standof Mono Lake

Owens Lakelow stand

extreme low standof Lake Tenaya

low standof Lake Tenaya

Medieval Warm Period Little Ice Age

AD 1300Event

wetter

drier

RecentWarming

Medieval Warm Period – comparatively dry

Little Ice Age – comparatively wet

Westernmost USA, Nevada dendrochronology (Hughes and Graumlich, 1996 book chapter)

and lake-level data

Stalagmite, Buddha Cave, east China (Paulsen et al., 2003 [Quaternary Science Reviews].

El Niño frequency change

A. Laguna Pallcacocha, Ecuador

B. Laguna Aculeo, Chile

C. Sacramento River, USA

D. Historical records

Compilation from Nunn (2007) book

Pacific Islands compilation

Compilation from Nunn (2007) book

Last-millennium climate changes in the Pacific: the AD 1300 Event

• Too much emphasis hitherto on discrete periods rather than transitions as the causes of environmental and societal change.

• The AD 1300 Event was the most rapid period of climatic change within the past few thousand years.

Source: Dahl-Jensen et al., 1998 [Science]

Part 2

Environmental changes on tropical Pacific Islands during the last

millennium

Qaranilaca (Sail Cave), Vanuabalavu Island, Fiji

Anthropogenic cave fill

Storm-wave deposit

-No sign of cave occupation during Medieval Warm Period (cave flooded?)

-Fill begins accumulating about AD 1400 (sea level has fallen?)

-Transient cave occupation begins about AD 1450 during Little Ice Age (sea level low)

-Cave fill now being eroded (sea level rising)

Kawai Nui wetland, O’ahu Island, Hawaii

-During Medieval Warm Period, Kawai Nui was an ocean bay (sea level high)

-During Little Ice Age, Kawai Nui became a brackish-water swamp (sea level low)

Tikopia Island, eastern outer Solomon Islands

Original research:

Kirch and Yen (1982)

1833 lithograph by Louis Auguste de Sainson

Ravenga Tombolo

Part 3

Societal changes on tropical Pacific Islands during the last millennium

(a) settlement-pattern change and the emergence of conflict

(b) end of cross-ocean interaction

Easter Island (Rapanui)

-Colonized about AD 690 (maybe AD 1200)

-AD 1300, conflict begins, statue-making frenzy

mata’a – obsidian spearheads

Tatuba Cave

Korokune hillfort

Dates for the establishment of hillforts and fortified caves in the Sigatoka Valley, Viti Levu Island, Fiji (courtesy of Dr Julie Field)

Tatuba Cave

Korokune hillfort

Changing settlement pattern, Kaua’I Island, Hawaii during the last millennium

New Zealand (not tropical!)

Beginning around AD 1300, coastal settlements were abandoned in favor of fortified hilltop settlements named pa. Conflict ensued.

The pa at Tolaga about 1780 (Herman Spöring)

Palau Islands, western tropical Pacific

Babeldaob Island Rock Islands

End of cross-ocean interaction

Part 4

Climatic forcing of last-millennium environmental and societal change

in the tropical Pacific Islands

Model of the “AD 1300 Event”

-Climate change drives environmental change

-Environmental change drives societal change

-Climate change also directly drives societal change

One example of societal response to climate forcing is settlement-pattern change

Warm, moist climate: sea level rising

Warm, dry climate: sea

level high

Cool, variable climate: sea

level low

Solar forcing (sunspot numbers) and Pacific climate change

Summer temperatures, Canadian Rockies

Precipitation and temperature, eastern China (98-year lag)

Solar forcing and sea-level change in the Pacific

Solar irradiance (∆14C) and sea-level change, Pacific Islands composite (90-year lag) from Nunn (2007) book.

Conclusion

• Climate change, both directly and through environmental filters, caused profound societal changes in the tropical Pacific Islands during the last millennium.

Nunn, P.D. 2007. Climate, Environment and Society in the Pacific during the Last Millennium. Amsterdam: Elsevier, 316 p.

Nunn, P.D. 2007. The AD 1300 Event in the Pacific Basin: overview and teleconnections. The Geographical Review, 97, 1-23.

Nunn, P.D. 2007. Holocene sea-level change and human response in Pacific Islands. Earth and Environmental Science, 98, 117-125.

Nunn, P.D., Hunter-Anderson, R., Carson, M.T., Thomas, F., Ulm, S. and Rowland, M. 2007. Times of plenty, times of less: chronologies of last-millennium societal disruption in the Pacific Basin. Human Ecology: An Interdisciplinary Journal, 35, 385-402.

Thank you for your attention.