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G. Steinmetz, National Geographic 2002

Great Plains Droughts and Megadroughts in Prehistory

Sheri Fritz, Department of Earth and Atmospheric Sciences, Robert B. Daugherty Water for Food Institute University of Nebraska - Lincoln

What can we learn from studying the past?

§  Patterns of natural drought variation §  Magnitude §  Duration §  Spatial extent

§  Response of landscape and biota to droughts of differing character

Arthur Rothstein

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2012 Drought (“Pan-continental”) Synchronous drought in multiple regions

Epic North American Droughts

Cook  et  al.    

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Stahle 2003

Tree-ring Reconstructions

Climate of the late Holocene (last ~4000 yr) Climate system in ~ same configuration as today

Ruddiman    2008  

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Major and Prolonged Drought Medieval “Mega-droughts”

Moon Lake, south-central North Dakota Laird, Fritz et al. 1996

Dust Bowl

Medieval Period

Tree-ring Reconstructions Central Plains Palmer Drought Severity Index

Dry

Wet

Cook et al. 2014

Medieval

Date (AD)

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Tree-ring Reconstructions Medieval “Mega-droughts”

Pan-continental drought

Saeger et al. 2009

Moon Lake, south-central North Dakota

Laird, Fritz et al. 1996

Medieval Roman

16th c

Late-Holocene “Mega-droughts”

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Holocene Drought Variability

Medieval Roman

mid-Holocene

Hobbs, Fritz et al. 2011

Kettle Lake, northwestern North Dakota

The Nebraska Sand Hills

Map  from  J.  Swinehart  and  D.  Loope  

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Nebraska Sand Hills Dunes Record Medieval Drought

Photo  by  David  Loope  

Nicholson and Swinehart 2005

Jumbo Fen, Nebraska Sand Hills

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Dunes Advance over Valleys during Major Drought

Nicholson and Swinehart 2005

V Sridhar et al. Science 2006;313:345-347

Published by AAAS

Altered Mean Wind Direction in Medieval Times

Contemporary Wind Direction

Medieval Wind Direction

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Cook et al. 2014

Oceanic Forcing of North American Drought

Southern Oscillation (ENSO)

Pacific Decadal Oscillation

Atlantic Multi-Decadal Oscillation

Dust and Vegetation Loss Amplify Drought Persistence

Cook et al. 2013

Pacific SST only

SST plus veg loss

SST plus veg loss plus dust

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Aa

Episodes of aeolian activity,based on loess record

0 5000 10000 15000 20000 25000Years Ago

LoessAeolian Sand

Optical ages(with ± 2 σ errors)

Miao et al, 2007

Dune and Loess Record of Paleoclimate

mid-Holocene

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

Age

(cal

enda

r yea

rs B

P)

20 40 60 80

Charco

al co

ncen

tratio

n

20 40 60

Cheno

podia

ceae

/Amara

nthac

eae

20 40 60

Poace

ae

20

Artemisi

a

20

Ambrosia -ty

pe

Iva xa

nthifo

lia -type

20

Pinus

Isoëte

sMyri

ophy

llum

Potamog

eton

Sagitta

ria

Typha

latifo

lia

Beaver Lake, Cherry County, Nebraska

Enhanced Fire during Wet Intervals

Schmieder, Fritz, Grimm et al. 2013

Grasses

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Early 20th century “pluvial”

Laws regulating stream flow were established in early 1900s in many parts of western US

Cook et al. 2011

• Droughts equivalent in magnitude to the most severe 20th century droughts have been recurrent every century, including pan-continental drought

• In many regions of western North America, pre-20th century droughts have lasted a decade or more - thus drought has been more persistent than in the 20th century

• In many parts of western NA, the early 20th century was unusually wet (pluvial)

• Paleo data provide useful targets for model exploration of the conditions that produce severe and persistent drought

Insights from the Long-term Record

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G. Steinmetz, National Geographic 2002

1:30 – 3:00 PM Today: Drought: A Prehistoric Perspective: Paul Hanson, Rolfe Mandel, Connie Woodhouse