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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