“Prairies need to brace for global-warming havoc”

National Post, Nov. 1, 1987

According to Environment Canada, over the next 50-100 years: * Mean annual temperatures will rise by 5°C; * Drought frequency will increase 13-fold ; * Crop yields are expected to tumble 10-30%, leading to major losses of export revenue; e.g. the 1988 drought caused losses of $4billion to the Prairie agricultural sector.

The geography of drought in the Canadian Prairies: an example

Devil’s Lake, NDat 1000-yr high

Summer rainfall, 2001

zonal flow:no drought

(~30%)

drought in

west(~30%)

drought ineast(~30%)

droughtthroughout(~10%)

The geography of drought in the Canadian Prairies: II. Synoptic patterns

(percentages based on frequency in summers of 1960’s)

Mega-Droughts in the Great

Plains (A.D. 1800-

1960):

spatial extent based on historical records and tree-

ring reconstructions

Prairie palaeo-

ecological sites

discussed in the lecture

1. Elk Lake, MN2. Moon Lake, ND3. Chappice Lake, Alta.4. Como Lake, CO

LGM vegetatio

n(18 ka 14C yrs BP):North

America

Elk Lake, Minn

From: PAGES News

Elk Lake, Minn:

Precipitation patterns

from: Donovan et al., (2002) Quat. Sci Rev. 21, 605-624.

Elk Lake, Minn.Palmer Drought Indices*

measured soil H20 normal soil H20

= x100* from: Donovan et al., (2002) Quat. Sci Rev. 21, 605-624.

Elk Lake: MinnStrandlines from drought of

1930’s

Photo: 1938

from: Donovan et al., (2002) Quat. Sci Rev. 21, 605-624.

Holocene climate: Elk Lake

From PAGES newsletter

Holo

cen

e c

limate

: E

lk L

ake

, M

inn

from: Wilson et al., (2002) Quat. Sci Rev. 21, 625-646.

wet

dry

Moon Lake, ND: Drought frequency pre- and post-A.D. 1250

Dia

tom

-infe

r red

From: Laird et al., 1998. J. Paleolimnology, 19, 161-179.

Moon Lake, ND:

pollen record

Chappice Lake, Alberta:pollen and macrofossils

From: Vance et al., (1992) Geology 879-882.

MWPLIA

Neo-glacial

Hypsithermal

Como Lake, CO:

pollen record

Deserts of the the US

southwest

Packrat midden evidence

www.geo.arizona.edu/palynology/geos462/28packrats.html

Altitudinal displacement of common plant species (modern - LGM)

from: Davis and Shaw (2001) Science 292, 673-679.

Altitudinal shifts in vegetation and inffered temperature changes in the

American SW

~1000 m = ~ 6°C

~550 m = ~ 3.5°C

From

: B

rake

nri

dge (

197

8)

Quate

rnary

Rese

arc

h,

9,

22-4

0.

Packrat middens:palaeotemperature record

www.geo.arizona.edu/palynology/geos462/28packrats.html

LGM vegetationand storm

paths:North

America

LGM

winter

summer

modern

Plu

via

l la

kes

of

the

Am

eri

can

SW

Estancia

Relict lake shorelines, Death Valley and pluvial Lake

Bonneville

Changes in the

level of pluvial Lake

Lahontan, 0- 26 ka

BP

Data from: Benson (1978) Quaternary Research 9, 300-318.

dessication of Walker lake basin

Changes in the lake

level inEstancia Basin,

NM (cold-adapted)

Lake Bonneville basin and palaeosites (Homestead

Cave)

Homestead cave midden

Late Glacial ~1000 BP

Duck bones in midden strata from raptor feeding

From Madsen et al., (2001), Palaeo3, 167, 243-271

dess

icati

on

?

LGM

- H

olo

cene d

iato

m

ass

em

bla

ges,

Ow

ens

Lake

, C

A

Bradbury, in press

Holocene palaeoclimates: Great Salt Lake and

environs

data from Madsen et al., (2001), Palaeo3, 167, 243-271

Montezuma Well, NM:

pollen record

Palaeohydrologic proxies:desert varnish chemistry

Alternation between Fe and Mn-rich oxide layers

is a wet-dry indicator

Stalagmite geochemistryst

ala

gm

ite

Annual ringA dark band of calcite rich with microbes is laid down at the beginning of the rainy season; clearer layers follow as water continues to flow. In wet years the calcite layers are thick; in the dry years aragonite forms, indicating strongly evaporative conditions. Under hyperarid conditions (such as at present) no water flows and no minerals are deposited.

Stalagmite records of palaeoclimate in the US

SW

From: Polyak and Asmerom (2001) Science, 294, 148-151

PuebloCulture

area

Devil’sHole,

NV

Anasazi

MH

Guadalupe Mountains record

Late Holocene palaeoclimate

and Pueblo cultures of

the American SW

3000 2000 1000 0yrs BP

Mogollon

AnasaziClassic Hohokam

wetter drier

Photo: James Kay

Cave geochemistry:the Devil’s Hole, NV record

in process

Devil’s Hole: challenging the orbital model or tracking local palaeoclimate?

from: Karner and Muller (2000) Science, 288, 2143-2144.

Eurasian vegetation and selected palaeosites

1. Loess Plateau2. Issyk-Kul3. Ozerki4. Aral Sea

Loess Plateau: North China

Loess Plateau: last 100

ka of palaeo-climate record

from: Xiao (1998) Pages News, Vol. 6, No.1, p.5

Holocene palaeoclimate:Lake Issyk-Kul, Kyrgyzstan

from: Rasmussen et al., (2001) Pages News, 9, No. 2

Holocene palaeo-climate, Ozerki

Swamp, Kazakhsta

n

from: Tarasov et al., (1997) Palaeo3, 136, 281-292

January July Annual

Aral Sea (1960-1990):World’s fourth largest lake suffered

40% reduction in area;60% reduction in volume

increase in salinity from 9 - 30 g/L

cause: irrigation demand in Uzbekistan

Hol o

cene c

l imate

: A

ral B

asi

n

from: Boomer et al., (2000) Quat. Sci. Rev., 19, 1259-1278.