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

NOAA/IPRC Workshop on Climatic Changes in the Last 1500 Years: Their Impacts on Pacific Islands , East-West Center, 13 th November 2007 A Shock to the System: Climatic Disruption of Pacific Island Societies around AD 1300. Patrick D. Nunn Professor of Oceanic Geoscience

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

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  1. NOAA/IPRC Workshop onClimatic Changes in the Last 1500 Years:Their Impacts on Pacific Islands, East-West Center, 13th November 2007A 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

  2. Climate, Environment and Society • Climatic change produces environmental change. Channelled scablands, NW USA

  3. 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]

  4. Climatic Influences on Environments:insights from high-resolution data series Solar irradiance (14C) and sea-level change at Farm River Marsh, NE USA Source: van de Plassche et al. (2003 [Geology]

  5. Climatic Influences on Environments:an empirical study from the Pacific Kurile Islands, Northwest Pacific Ocean Source: Razjigaeva et al., 2004 [Palaeo3]

  6. 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

  7. 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])

  8. Climatic Influences on Human Society:watershed studies from the Pacific Climate influence on society through environmental filter Source: William R. Dickinson

  9. 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

  10. The Pacific Basin

  11. Volcanic Pacific Islands

  12. Limestone Pacific Islands

  13. Pacific Island paleoclimate archives

  14. History of human settlement of the Pacific Islands

  15. Organization of this talk • Last-millennium climate change in the Pacific • Environmental changes on tropical Pacific Islands during the last millennium • Societal changes on tropical Pacific Islands during the last millennium • Possible climate forcing of last-millennium environmental and societal change in the tropical Pacific Islands: the AD 1300 Event

  16. Part 1Last-millennium climate change in the Pacific

  17. 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.

  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

  19. Compilation from Nunn (2007) book

  20. Westernmost USA, Nevada dendrochronology (Hughes and Graumlich, 1996 book chapter) and lake-level data Medieval Warm Period – comparatively dry Little Ice Age – comparatively wet

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

  22. El Niño frequency change • Laguna Pallcacocha, Ecuador • Laguna Aculeo, Chile • Sacramento River, USA • Historical records Compilation from Nunn (2007) book

  23. Pacific Islands compilation Compilation from Nunn (2007) book

  24. 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]

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

  26. 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)

  27. 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)

  28. Tikopia Island, eastern outer Solomon Islands Original research: Kirch and Yen (1982)

  29. Ravenga Tombolo 1833 lithograph by Louis Auguste de Sainson

  30. Part 3Societal changes on tropical Pacific Islands during the last millennium • settlement-pattern change and the emergence of conflict • end of cross-ocean interaction

  31. Easter Island (Rapanui) • Colonized about AD 690 (maybe AD 1200) • AD 1300, conflict begins, statue-making frenzy mata’a – obsidian spearheads

  32. Tatuba Cave Dates for the establishment of hillforts and fortified caves in the Sigatoka Valley, Viti Levu Island, Fiji (courtesy of Dr Julie Field) Korokune hillfort

  33. Tatuba Cave Korokune hillfort

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

  35. 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)

  36. Palau Islands, western tropical Pacific Babeldaob Island Rock Islands

  37. End of cross-ocean interaction

  38. Part 4Climatic forcing of last-millennium environmental and societal change in the tropical Pacific Islands

  39. Model of the “AD 1300 Event” • Climate change drives environmental change • Environmental change drives societal change • Climate change also directly drives societal change

  40. 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

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