Late Quaternary environments in the Arctic region.

LateQuaternary

environments in the

Arctic region

Late Tertiary climatic decline in the Arctic

from: White et al. (1997) Palaeo3 30, 293-306.

The North Polar

region: dots are pollen

analysis sites

RSL - temperature - sea ice conditions in the Arctic

Ocean

North Atlantic - Arctic Ocean water exchange rates about 37% lower at LGM than at present

Iceworld: Wisconsinan glaciation

Bering Sea/Beringia

sill(-48m)

submerged

exposed

The most recent submergence: ~10 - 11 000 cal. yrs BP

exposed

submerged

Eustatic sea-level curve from: Lambeck & Chappell (2001) Science 292, 679-

Trans-Beringia mammal migrations during the

QuaternaryBeaverLynxSnow & mountain sheepMooseElkBearsWolverineWolfArctic foxArctic hareBisonMountain goatCoyoteKit fox

CamelsHorse

(and humans)

Multiple migrationsMa BP

0

0.3

0.6

0.9

1.2

1.5

1.8

2.0

M.columbi

M.meridionalis

M.trogontheri

M.primigenius

0

20

40

60

80

100

120

140

B.antiquus

ka BP

B. bison

B.priscus

land water ice

Mammoths Bison

Asia Beringia N America Asia Beringia N America

?

?

Beringia: glacial refuge

The “mammoth-steppe” controversy

www.photostar-usa.com/photography/destination/Beringia/beringia.htm

adapted from: Lister,A. and Bahn, P. (1994) “Mammoths”, Macmillan

Faunal composition of the “Mammoth steppe”

from: Lister,A. and Bahn, P. (1994) “Mammoths”, Macmillan

SIBERIA ALASKA

Why steppe?Dale Guthrie (U. Alaska) argued* that the diverse array of grazers that comprised the Late Pleistocene megafauna of Beringia, which included the mammoth, wooly rhinoceros, saiga antelope, steppe bison, and Chersky horse, could have been supported only by arid, grass- and forb-dominated ecosystems, not by tundra, which today supports only caribou and muskoxen.Bison and saiga antelope in particular were considered to indicators of the ‘steppe-like’ nature of the plant community.

See article by Guthrie in Hopkins et al., (1982) “Palaeoecology of Beringia”, Academic Press.*

Why not tundra?“The tundra and boreal landscape is not simply a product of average annual rainfall and degree days. Vegetation itself affects soil character. The largely toxic insulating plant mat, shielded from high evaporation, promotes permafrost, or at least very cool soils, and limits available nutrients.This, in turn favors the same plants that created those soil conditions. The cycle propels itself; conservative plants on low-nutrient soils must defend themselves against herbivory by large mammals. This largely toxic vegetation limits the species diversity and biomass of the large mammal community”.

Guthrie, R.D. (1990) "Frozen Fauna of the Mammoth Steppe:

The Story of Blue Babe”, Chicago University Press, p. 207

The pollen

evidence:percent abundan

ce of common

plants

Data from: Elias et al. (1997) Nature 386, 60-63.

Central Beringia palaeoenvironments

from: Elias et al. (1997) Nature 386, 60-63.

Late Glacial: birch-heath-graminoid tundra with small ponds; slightly warmer than PD at 11ka BP; mesic tundra.

LGM: birch-graminoid tundra with small ponds; arctic climate, drier than late glacial; no steppe-tundra elements.

>40 ka BP: birch-heath-graminoid tundra with no steppe elements, shrubs not important.

Full-glacial upland tundra*

*plants recorded from a buried [21.5 cal. yr BP] tundra surface blanketed by 1m of tephra in the Seward Peninsula. from: Goethchus and Birks (2001) Quat Sci. Rev., 20, 135-147.

Tundra types in northern Alaska

From: Walker et al., (2001) Quat. Sci. Rev., 20, 149-163

Moist acidic tundra Moist nonacidic tundra

~x2 plant diversity;10x extractable Ca;

higher soil pH;O layer 50% as thick;

30% deeper active layer

Iceworld: Wisconsinan glaciation

storm paths

H

H

Is moist non-acidic tundra the modern equivalent of tundra-steppe? Was it sustained by loess deposition?

Climatic change in the Holocene: the driving forces at 60°N

750 830

Late

Quate

rnary

polle

n

reco

rd -

East

ern

Beri

ngia

after: Cwynar (1982)

Holocene changes in vegetation; eastern

Beringia

C. Alaska Yukon

warm

er

co

ole

rd

rier?

m

ois

ter

su

mm

ers

From: Grimm et al. (2001)

from: Short et al. (1985) in Andrews, JT “Quaternary Environments, Eastern Canadian Arctic…”

Deglaciation of the Laurentide Ice Sheet

from: Hughes (1989)

Date

d o

ccurr

ence

s of

biv

alv

es:

Baffi

n Isl

and

from: Kelly (1985) in Andrews, JT “Quaternary Environments, Eastern Canadian Arctic…”

Location of core

PS21880(green dot)

and Raffles

O (red dot)

Relative abundance of

sea-ice diatoms

(= length of sea-ice season?) at PS21880

“H

yp

sit

herm

al”

“

Neog

lacia

l”

From: Koc et al. (1993) Quat. Sci. Rev., 12, 115-140.

The diatom record from

Raffles So, East

Greenland

from: Cremer et al., (2001) J. Paleolimnology, 26, 67-87

“H

yp

sit

herm

al”

“

Neo-

g

lacia

l”

Late

Qu

ate

rnary

SS

T,

Gre

enla

nd

-Ice

lan

d-N

orw

ay S

eas

from: Koc et al. (1993) Quat. Sci. Rev., 12, 115-140.

Location of core

GPC-22082208

N Pole

from: Gard (1993) Geology, 21, 227-230.

Coccolithophores in core GPC-2208

early-mid Holocene? from: Gard (1993) Geology, 21, 227-

230.

The pollen record from N. Norway

from: Alm (1993) Boreas 22:171-188

Late Quaternary climate change in the Arctic from pollen records

from: CAPE Project

from: CAPE Project

Late Holocene climate change, Alaska

2500 2000 1500 1000 500 0

no data

Glacial advances and retreats; Gulf of Alaska*

Lake geochemistry; Alaska Range**

*Wiles et al., (2001) Quat. Sci. Rev. 20, 449-461; ** Hu et al., (2001) Proc. Nat. Acad. Sci.

years BP

warm cool

Environmental change in the Arctic,

AD1600-2000

from: Overpeck et al., (1997) Science 278, 1251-1256

from: Overpeck et al., (1997) Science 278, 1251-1256

LateQuaternary

environments in

Antarctica

The Holocene climatic optimum in Antarctica

Climatic change in the Holocene: the driving forces at 60°S

830 750S

Holocene relative sea-level change in the Vestfold Hills,

Antarctica*

*from: Zwartz et al., (1998) Earth and Planetary Science Letters, 155, 131-145.

Ele

vati

on

(m

, asl

)

ka, BP10 8 6 4 2 0

+12

+8

+4

0Climatic optimum

RSL

outer shelfdeglaciated

inner shelf and nearshore

areas deglaciated

En

vir

on

menta

l ch

an

ge in

Anta

rcti

ca (

Ard

ley P

enin

sula

) base

d o

n p

eng

uin

dro

pp

ings

Inferred temperature

from: Sun et al., (2000) Nature, 407, 858.lo

w p

enguin

popula

tion

Recent (post-AD 1980) changes in Antarctic lakes

From: Quayle et al., (2002) Science, 295, 645.

Responses to C20th climate change in

Antarctica• Ice shelf disintegration (e.g. N. Larsen &

Wordie Shelf); • Summer sea-ice area has declined by

>25% • Rapid spread of flowering plants (e.g.

Antarctic hairgrass has expanded its range 25-fold since 1964)

• New lichen species colonizing recently deglaciated areas