Transcript AGU_PressConference/agu_press_overview - Arctic

Climate Change in the Arctic and the
Intensifying Hydrologic Cycle
Ongoing research is documenting pronounced changes
in the storage and transport of water in the Arctic’s
atmosphere, rivers, lakes, ice and seas
The Arctic’s hydrologic cycle seems to be intensifying,
most likely in response to global climate change
Our best climate models project that the
Arctic will become warmer. And the
Arctic is indeed warming
http://zubov.atmos.uiuc.edu/ACIA/
http://zubov.atmos.uiuc.edu/ARCTIC/
As well as wetter. And
Arctic precipitation has
indeed increased.
http://zubov.atmos.uiuc.edu/ACIA/
The North Atlantic Oscillation
The North Atlantic Oscillation
(NAO) (very similar to the
Arctic Oscillation, or AO) is a
big player in high latitude
climate variability. Its “rise”
From about 1970-1995
contributed strongly to
winter/spring warming and
changes in precipitation. Some
evidence suggests that
anthropogenic forcing may
favor the “warm” positive mode
of the NAO/AO.
Courtesy Martin Visbeck, LDEO
http://www.ldeo.columbia.edu/
Change in combined discharge from
the 6 largest Eurasian arctic rivers
4000
Average discharge anomaly for 5 year increments
Cumulative volume anomaly from river inputs
150
3000
100
2000
50
1000
0
0
2005
2000
1995
1990
1985
1980
1975
1970
1965
1960
1955
-2000
1950
-100
1945
-1000
1940
-50
1935
Discharge anomaly (km3/y)
200
Cumulative volume anomaly (km3)
Yenisey, Ob', Lena, Kolyma, Severnaya Dvina, Pechora
Years
*Anomalies are relative to average discharge from 1936 to 1955
http://ecosystems.mbl.
edu/partners/
Change in the seasonality of combined discharge
from the 6 largest Eurasian arctic rivers
Yenisey, Ob', Lena, Kolyma, Severnaya Dvina, Pechora
50
50
0
0
-50
-50
100
Freshet (May-June)
Summer (July-September)
100
Freeze-up (October)
100
50
50
0
0
-50
-50
1935
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
Winter (November-April)
1935
1940
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
Discharge anomaly (km3)
100
Average discharge anomaly for 5 year increments
*Anomalies are relative to average discharge from 1936 to 1955
http://ecosystems.mbl.
edu/partners/
Ocean
trends on the
1930 – 1965
1965 – 1995
N/AO
Russia
Wind forces
fresh water
rapidly off-shelf
.
N/AO
Eastward wind
traps freshwater
on the shelf
Russia
Steele & Ermold, 2004
http://psc.apl.
washington.edu/
1.6
saltier
0.4
0
salinity trend
(decade-1)
-0.4
Shelves get
saltier
Jet Stream
Shelves get
river
discharge fresher
is lower
Jet
Stream
river
-1.6
discharge
is higher
fresher
But why??
Salinity anomaly
(in negative freshwater volume, 103 km3)
trends in the
adapted from Häkkinen &
4
.
Proshutinsky, 2004
 Data: no obvious trends
2
0
 Model: trends are unreliable
-2
-4
data
1950
1960
model
(de-trended)
1970
1980
1990
2000
http:/www.psc.
apl.washington.edu/
However! Working with the same data as H & P,
 Nechaev et al. (2004) found a slight (~5%) freshening trend, while
 Swift et al. (2004) found a shift to higher salinities in the 1970’s.
Bottom line: The jury is still out.
Sept. 2002
Starting about 1960, the Arctic
sea ice cover began to shrink,
especially in summer and early
autumn. The past three
Septembers have seen extreme
sea ice losses - 2002 probably
had the least sea ice of the past
100 years.
Sept. 2004
http://www.nsidc.org/
http://zubov.atmos.uiuc.edu/
Age and Thickness of Sea Ice
has decreased.
September 1987
September 2001
Open
Water
Younger,
thinner
Ice
Open
Water
Younger,
thinner
Ice
Older,
thicker
Ice
Older,
thicker
Ice
http://psc.apl.
washington.edu/
Age:
OW 0 1
2 3 4 5 6
8
10+
• Area of old ice has decreased dramatically during the last 15 years.
• Recirculation of younger, thinner sea ice back to the Alaskan coast may
explain recent minima in summer sea ice extent.
• These changes are related to the Arctic Oscillation.
Courtesy K. Steffen, NSIDC
The Greenland ice sheet now
seems to be losing mass - as
are many of the glaciers in the
Arctic. This is contributing
to sea level rise. In the
summer of 2002, the area of
the Greenland ice sheet
undergoing surface melt was
the greatest observed since
1979, when monitoring by
satellites began.
http://cires.colorado.edu/steffen/
Permafrost
Permafrost – perenially frozen
ground - covers much of the
northern land area. In some
areas of the Arctic, it may be
greater than 1500 m in
thickness. Permafrost seems
to be warming and melting,
with impacts on ecology,
wildlife habitat and
infrastructure.
http://www.nsidc.org/
http://www.uaf.
edu/water/
Much of the Arctic is a desert, where freshwater is
scarce and often frozen. The snowpack is critical to
residents who access subsistence resources in winter
http://www.uaf.edu/water/
In many areas of the Arctic, humans rely on
snow and ice for drinking water.
http://www.uaf.edu/water/
Photo: Melinda Reynolds
Arctic residents rely on subsistence foods, such as these
waterfowl. The birds depend on freshwater perched atop
continuous permafrost in summer.
http://www.uaf.edu/water/
Photo:Bill West AK/RO/00946
We must engage arctic residents as meaningful
participants in the freshwater cycle, and the first to
face the impacts of a changing climate.
http://www.uaf.edu/water/