Medieval Climate Anomaly

Climate in Medieval TimeBradley, R. et al

Cultural Responses to Climate Change During the Late Holocene

deMenocal, P.

Medieval Warm Epoch → Medieval Climatic Anomaly

Bradley’s hypothesisProlonged droughts in some areas and exceptional rains in others suggest that changes in frequency or persistence of circulation regimes may account for the climate in this period.

“Persistent positive North Atlantic Oscillation mode dominated the medieval climate anomaly”, Science

Trouet, 2009

Cultural Responses to Climate Change

James Hutton, 1785: The present is the key to understanding the past.Peter deMenocal, 2001: The past must be used to understand the present.

Hypothesis: Water availability, rather than temperature, is the key climatic determinant for life in semiarid expanses across the planet.

Relevance: Further study of past cultural adaptations to persistent climate change may provide valuable perspective on

possible responses of modern societies to future climate change.

4 Case studies

• Akkadian collapse (4200 years ago)• Mayan collapse (1200 years ago)• Mochica collapse (1500 years ago)• Tiwanaku collapse (1000 years ago)

Archeological and paleoclimate histories that illustrate past cultural responses to late Holocene climate change.

Akkadian empire (4300 to 4200 B.P.)

Gulf of Oman sediment core M5-422: A detailed record of variations in regional dust export based on mineralogical and geochemical tracers of wind-borne sediments from Mesopotamian sources (Fig. 4)

Roy, 2003

Cullen, 2000

Excavated residence from Tell Leilan

Esther

Fig. 4

Classic Maya empire (1200 to 1000 B.P.)

Sediment cores from Lake Punta Laguna and Lake Chichancanab document an abrupt onset of more arid conditions spanning ~200 years between 1200 and 1000 years B.P.

Fishleigh, 2012

Fig. 6 Sediment data from the lakes

Moche IV-V Transformation (1400 B.P.) and Tiwanaku collapse (900 to 300 B.P.)

Fig. 7 Quelccaya, Peru

deMenocal’s Take Home message

Further study of past cultural adaptations to persistent climate change may provide valuable perspective on possible responses of modern societies to future climate change.

Tuesday: Little Ice Age (1350 – 1850 A.D.)

Formerly the earth produced all sortsof fruit, plants and roots.But now almost nothing grows…Then the floods, the lakes and the blue wavesbrought abundant fish.But now hardly one can be seen.The misery increases more.The same applies to other goods…Frost and cold torment peopleThe good years are rare.If everything should be put in a verseOnly a few take care of the miserables…Olafur Einarson (1573-1659)Icelandic priest