Late Quaternary environments in the Arctic region

1
LateQuaternary environments in the Arctic region
2
Late Tertiary climatic decline in the Arctic
from White et al. (1997) Palaeo3 30, 293-306.
3
The North Polar region dots are pollen analysis
sites
4
RSL - temperature - sea ice conditions in the
Arctic Ocean
North Atlantic - Arctic Ocean water exchange
rates about 37 lower at LGM than at present
5
Iceworld Wisconsinan glaciation
6
Bering Sea/Beringia
submerged
sill (-48m)
exposed
7
The most recent submergence 10 - 11 000 cal.
yrs BP
submerged
exposed
Eustatic sea-level curve from Lambeck Chappell
(2001) Science 292, 679-
8
Trans-Beringia mammal migrations during the
Quaternary
Beaver Lynx Snow mountain sheep Moose Elk Bears
Wolverine Wolf Arctic fox Arctic
hare Bison Mountain goat Coyote Kit fox
Camels Horse
(and humans)
9
Multiple migrations
Ma BP
ka BP
Mammoths
Bison
0 0.3 0.6 0.9 1.2 1.5 1.8 2.0
0 20 40 60 80 100 120 140
B. bison
M. primigenius
M. columbi
B. antiquus
?
M. trogontheri
M. meridionalis
B. priscus
?
Asia Beringia N America
Asia Beringia N America
land water ice
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Beringia glacial refuge
11
The mammoth-steppe controversy
www.photostar-usa.com/photography/destination/Beri
ngia/beringia.htm
12
adapted from Lister,A. and Bahn, P. (1994)
Mammoths, Macmillan
13
Faunal composition of the Mammoth steppe
SIBERIA
ALASKA
from Lister,A. and Bahn, P. (1994) Mammoths,
Macmillan
14
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.
15
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
16
The pollen evidencepercent abundance of common
plants
Data from Elias et al. (1997) Nature 386, 60-63.
17
Central Beringia palaeoenvironments
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. gt40 ka BP
birch-heath-graminoid tundra with no steppe
elements, shrubs not important.
from Elias et al. (1997) Nature 386, 60-63.
18
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.
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Tundra types in northern Alaska
Moist acidic tundra Moist nonacidic
tundra
x2 plant diversity 10x extractable Ca higher
soil pH O layer 50 as thick 30 deeper active
layer
From Walker et al., (2001) Quat. Sci. Rev., 20,
149-163
20
Iceworld Wisconsinan glaciation
Is moist non-acidic tundra the modern equivalent
of tundra-steppe? Was it sustained by loess
deposition?
storm paths
21
Climatic change in the Holocene the driving
forces at 60N
750 830
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Late Quaternary pollen record -Eastern Beringia
after Cwynar (1982)
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Holocene changes in vegetation eastern Beringia
C. Alaska Yukon
warmer cooler drier? moister summers
From Grimm et al. (2001)
24
from Short et al. (1985) in Andrews, JT
Quaternary Environments, Eastern Canadian
Arctic
25
Deglaciation of the Laurentide Ice Sheet
from Hughes (1989)
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Dated occurrences of bivalves Baffin Island
from Kelly (1985) in Andrews, JT Quaternary
Environments, Eastern Canadian Arctic
27
Location of core PS21880(green dot) and
RafflesO (red dot)
28
Relative abundance of sea-ice diatoms ( length
of sea-ice season?) at PS21880
Hypsithermal Neoglacial
From Koc et al. (1993) Quat. Sci. Rev., 12,
115-140.
29
The diatom record from Raffles So, East Greenland
Hypsithermal Neo-
glacial
from Cremer et al., (2001) J. Paleolimnology,
26, 67-87
30
Late Quaternary SST, Greenland-Iceland-Norway
Seas
from Koc et al. (1993) Quat. Sci. Rev., 12,
115-140.
31
Location of core GPC-2208
N Pole
2208
from Gard (1993) Geology, 21, 227-230.
32
Coccolithophores in core GPC-2208
early-mid Holocene?
from Gard (1993) Geology, 21, 227-230.
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The pollen record from N. Norway
from Alm (1993) Boreas 22171-188
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(No Transcript)
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Late Quaternary climate change in the Arctic from
pollen records
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from CAPE Project
37
from CAPE Project
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Late Holocene climate change, Alaska
Glacial advances and retreats Gulf of Alaska
Lake geochemistry Alaska Range
warm cool
no data
years BP
Wiles et al., (2001) Quat. Sci. Rev. 20,
449-461 Hu et al., (2001) Proc. Nat. Acad.
Sci.
39
Environmental change in the Arctic, AD1600-2000
from Overpeck et al., (1997) Science 278,
1251-1256
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from Overpeck et al., (1997) Science 278,
1251-1256
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LateQuaternary environments in Antarctica
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The Holocene climatic optimum in Antarctica
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Climatic change in the Holocene the driving
forces at 60S
S
830 750
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Holocene relative sea-level change in the
Vestfold Hills, Antarctica
12 8 4 0
RSL
Elevation (m, asl)
Climatic optimum
10 8 6 4
2 0
ka, BP
inner shelf and nearshore areas deglaciated
outer shelf deglaciated
from Zwartz et al., (1998) Earth and Planetary
Science Letters, 155, 131-145.
45
low penguin population
Environmental change in Antarctica (Ardley
Peninsula) based on penguin droppings
Inferred temperature
from Sun et al., (2000) Nature, 407, 858.
46
Recent (post-AD 1980) changes in Antarctic lakes
From Quayle et al., (2002) Science, 295, 645.
47
Responses to C20th climate change in Antarctica

• Ice shelf disintegration (e.g. N. Larsen Wordie
  Shelf)
• Summer sea-ice area has declined by gt25
• Rapid spread of flowering plants (e.g. Antarctic
  hairgrass has expanded its range 25-fold since
  1964)
• New lichen species colonizing recently
  deglaciated areas