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Freshwater Ecosystems and Climate Change: Impacts on
Lake Ice, Fishes, and Hydrology
John J. MagnusonCenter for Limnology
UW-Madison
Main Points of Confronting Climate Change in the
Great Lakes Region 1. Climate is changing globally and in our region.
2. Impacts have already occurred and will get worse.
3. Emissions of greenhouse gases especially CO2 contribute to these changes.
4. Actions taken now can reduce the most severe future impacts.
UCS & ESA 2003.
Three Water Examples
Lake Ice CoverFish Habitat
Water Levels and Flows
The Invisible PresentThe Invisible Place
Magnuson 2006
0
30
60
90
120
150
180
1850 1875 1900 1925 1950 1975 2000
142 Years (1856 - 1998)
Lake Mendota, WisconsinIc
e C
over
(Day
s)1
Year
Magnuson 2004
0
30
60
90
120
150
180
1850 1875 1900 1925 1950 1975 2000
142 Years (1856 - 1998)
Interannual VariabilityIc
e C
over
(Day
s)10
Years
Magnuson 2004
0
30
60
90
120
150
180
1850 1875 1900 1925 1950 1975 2000
142 Years (1856 - 1998)
Dynamics from the Central PacificIc
e C
over
(Day
s)50 Years
(1949 -1998)
El Niño Years
Magnuson 2004
0
30
60
90
120
150
180
1850 1875 1900 1925 1950 1975 2000
Dur
atio
n of
Ice
Cov
er (D
ays)
DurationLinear ModelBest ARMA Mo
Mon
ths
of I
ce C
over
1850 1900 1950 2000
5
4
3
2
1
0
Long-Term Changes in Ice Cover Duration
Lake Mendota, Wisconsin
35
37
39
41
43
45
47
49
1890 1910 1930 1950 1970 1990 2010
Annual
Air T
emper
ature
(F)
increase = 0.7F/decadeincrease = 0.04F/decade
Wisconsin Air Temperatures 1895-2005
Data from State Climatology Office
0
30
60
90
120
150
180
1850 1875 1900 1925 1950 1975 2000
Dur
atio
n of
Ice
Cov
er (D
ays)
DurationLinear ModelBest ARMA Mo
Mon
ths
of I
ce C
over
1850 1900 1950 2000
5
4
3
2
1
0
Press & Pulse - Change in Extreme Events
Lake Mendota, Wisconsin
Winter is a part of our “Sense of Place.”
We are losing winter as we knew it!
Magnuson 2006
The Invisible PresentThe Invisible Place
1850 1900 1950 2000
Jan 1
Dec 1
Feb 1
Mar 1
Apr 1
May 1
Freeze
Breakup
Lake / BayChequamegon Bay
ShellMendotaMonona
RockGeneva
Magnuson 2004
Changes in Ice Dates Around Wisconsin
Changes around theNorthernHemisphere
(36-37 of the 39 time seriesare in the directionof warming)
Source: IPCC 3rd Assessment 2001 Modified from Magnuson et al. 2000
1840 1880 1920 1960 2000
Nov 1
Dec 1
Jan 1
Feb 1
Mar 1
Apr 1
May 1
Ice
On
Ice
Off
MacKenzie River, NW Terr.
Kallavesi, Finland
Lake Mendota, WI
Lake Mendota, WI
Grand Traverse Bay, Lake Michigan
Baikal, Russia
Grand Traverse Bay, Lake Michigan
Kallavesi, Finland
Baikal, Russia
Changes around theNorthernHemisphere
(36-37 of the 39 time seriesare in the directionof warming)
Source: IPCC 3rd Assessment 2001 Modified from Magnuson et al. 2000
1840 1880 1920 1960 2000
Nov 1
Dec 1
Jan 1
Feb 1
Mar 1
Apr 1
May 1
Ice
On
Ice
Off
MacKenzie River, NW Terr.
Kallavesi, Finland
Lake Mendota, WI
Lake Mendota, WI
Grand Traverse Bay, Lake Michigan
Baikal, Russia
Grand Traverse Bay, Lake Michigan
Kallavesi, Finland
Baikal, Russia
Toronto Harbor
Toronto Harbor, Ontario
Changes around theNorthernHemisphere
(36-37 of the 39 time seriesare in the directionof warming)
Source: IPCC 3rd Assessment 2001 Modified from Magnuson et al. 2000
1840 1880 1920 1960 2000
Nov 1
Dec 1
Jan 1
Feb 1
Mar 1
Apr 1
May 1
Ice
On
Ice
Off
MacKenzie River, NW Terr.
Kallavesi, Finland
Lake Mendota, WI
Lake Mendota, WI
Grand Traverse Bay, Lake Michigan
Baikal, Russia
Grand Traverse Bay, Lake Michigan
Kallavesi, Finland
Baikal, Russia
Suwa Ko, Japan
Omiwatari on Suwa Ko on January 12, 2003
Takayuki Hanazato
y = 0.0115x - 40.579
R2 = 0.0086
y = 0.1921x - 365.31
R2 = 0.4728-60
-30
0
30
1400 1500 1600 1700 1800 1900 2000
regression 1443-1825
regression 1800-1993
Lake Suwa, Japan, Ice-on Time Series from 1443 - 1993(30 days subtracted from years before 1880)
Ice-
On
Dat
e (0
= D
ec. 3
1)
What is Happening?
IPCC 2001
Suwa KoLake Ice Science Paper
Lake Ice
since1975
Lake Ice Data Extent versus Thermometer Measurements
ThermometerReadings
IPCC 2007
Simulated Annual Mean Surface Air Temperatures
Observed
Natural ForcingAlone
Natural and Anthropogenic
Forcing
IPCC 2007
Temperature Change in IPCC Scenarios
7.2°F
3.2°F
Confronting Climate Change in the
Great Lakes Region
Past, Current, and Future Climate Change
http://www.ucsusa.org/greatlakes
2003 updated 2005
PennsylvaniaEnd of this century scenarios
Temperatures Summer 7-9°F WarmerWinter 6-8°F Warmer
PrecipitationSummer Decrease 10-15%
Winter Increase 15-20%
Extreme heat more common.Frequency of extreme rain events more common
Pennsylvania Migrates Too!
http://www.ucsusa.org/greatlakes/
2030
2095
2003
20302095
Summer
Winter
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
Migrating ClimatesChanging Summers in Great Lakes Region
Current By 2095
http://www.ucsusa.org/greatlakes/
Do Fishes Care about Climate Change?
Cool WaterFishes
Cold Water Fishes
Warm WaterFishes
Magnuson May 2003
Lake trout > Coho salmon >
Chinook salmon > rainbow trout >
Brown trout > Whitefish >
Lake herring >Burbot >
Rainbow smelt > Alewife >
Walleye >
Yellow perch > Northern pike >
Sauger > Gizzard shad >
Freshwater drum > Carp sucker >
Black crappie > White crappie >
Emerald shiner >
Rock bass > Brown bullhead > Channel catfish >
Goldfish >
White sucker > Golden shiner >
Carp > Smallmouth bass >
White bass > Whiteperch >
Yellow bullhead > Longnose gar >
Pumpkinseed >
Bluegill >
0 5 10 15 20 25 30 35
Preferred Temperature ( oC)
cold cool warm
Corrected Figure 23: Temperature Groupings of Common Great Lakes FishThermal Guilds
of Freshwater FishesCold Cool Warm
UCS/ESA
White Sucker Coolwater Fish
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Other Coolwater Game Fishes
Where White Sucker Could Persist
DoubledGreenhouse GasesBase Climate
NO
YES
John Eaton and others
Minnesota Inland Lakes: Simulated Change in Thermal Habitat with CO2 Doubling
Warm Water Fishes
Cold Water Fishes
Cool Water Fishes
-100
+100
0
Stefanet al.
Clear LakesGreen Lakes
Cha
nge
in T
herm
al H
abita
t (%
)
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Northern Pike Smallmouth Bass
July/August Water Temperature (°C)
25 252323 21Rel
ativ
e Y
ear-
Cla
ss S
treng
th (%
)
21
Relation between Year-Class Strength and Summer Water Temperatures in the Bay of Quinte
Casselman 2002
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Shuter and Post 1990
SmallmouthBass
Smallmouth Bass dispersalMove north 120 km per 1°C warming Shuter et al. 2002
Extirpation of native species25,000 cyprinid populations extirpated to date from spread of smallmouth bass in Ontario Jackson & Mandrak 2002
Change inDistributionwith +4°CTemperature
What will Happen to the Fishes?
• Extinctions and extirpations at southern boundaries
• Northward movement of northern boundaries by 500km with CO2 doubling, again leading to extinctions and extirpations
• Greater losses of fishes in streams and shallow ponds than in deep lakes
• The Great Lakes refugia for cold water species• Invaders will cause extinction of some resident
species and changes in water quality.
Global Warming(temperature increase)
Speeds up GlobalWater Cycle
Effects of Global Warming on Water Cycle
More Extreme Weather Events• Droughts• Storms• Floods
Changes in the Hydrologic Cycle
Expectations
UCS/ESA 2003Magnuson April 2001
Winter
Summer
1900 2000 2100
+80
+40
0
-40
+80
+40
0
-40
Observed and projected change inaverage daily precipitation
(%)
Observed
Observed
High Emission
Low Emission
Low Emission
High Emission
Winter Summer Winter
Projected 2090-2099
Projected 2025-2034
Modeled 1961-1990
Wetter Dryer WetterUCS/ES
Seasonal Precipitation CycleD
aily
Ave
rage
Pre
cipi
tatio
n (m
m/d
ay)
5
4
3
2
A 2003
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24-Hour Events
7-Day Events
Increased Frequency of Heavy Rainfall
1900 2000 2100
x3
x2
1
x3
x2
1
0
Observed
Observed
Low Emission
Low Emission
High Emission
High EmissionR
elat
ive
to a
n A
vera
ge fr
om 1
961-
2000
UCS/ESA 2003
Water Levels and FlowsLast 50 Years
Magnuson 2003
Devils Lake
Anvil LakeShell Lake
Lake Stage Gages Shell Lake (WI) June 2002
Krohelski 2003
Shell Lake Annual Average Stage
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Shell Lake Annual Average Stage (feet)
25
20
15
10 1940 1970 2000Krohelski 2003
Fish Lake July 2000
Long-Term Water Level of Wisconsin Lakes and two Great Lakes
Magnuson et al. 2006
Great Lakes are BOLD.
Buffalo is in northern Wisconsin.
Mendota, Monona, and Fish are in southern Wisconsin.
Fish Lake isa seepage lake.
Stream Flows
Krohelski 2003
Grant River near Burton, Wisconsin (Baseflow)300
200
100
01930 1970 2000
Krohelski 2003USGS Station
!(
!(
!(
!(
!
!(
!(!(
!(
!( !(
!!(
!(
!(!(
!(
!
!( !(
Step Increase in Lake Stage, Stream Flow, and Groundwater Levels after 1970
Groundwater WellLake StageStream Flow
Gray = step increaseRed = no step increase
Magnuson et al. 2003
Shell Lake
Devils LakeUSGS Data
Baseflow
15
25
35
45
1940 1950 1960 1970 1980 1990 2000
Ann
ual P
reci
pita
tion
(Inch
es)
mean = 30.8inmedian = 30.0in
mean = 32.6inmedian = 32.8in
What happened to precipitation in Wisconsin?
Fall 50%Summer 30%Winter 17%Spring 3%
Stream-flow Sites with Significant Increasesin Minimum Daily Flow
between Two Periods (1941-70 and 1971-99)
IncreasesDecreasesNo Change
McCabe and Wolock
Another Cause of Increasein Water Levels and Flows
The Water Cycle Freshens Up
“Rivers are delivering increasing amounts of fresh water to the oceans.
The cause seems to be that higher concentrations of atmospheric carbon dioxide are having on water use by plants.water to the ocean.”
(Don Matthews Nature Feb 2006, see also Gedney et al.Nature Feb. 2006))
Water Levels and Flows Conclusions
• Lake stage (seepage lakes), baseflow in streams, and groundwater table have gone up in Wisconsin except for north central area.
• Reasons for the increases are varied and include change in precipitation, CO2 changes in plant physiology, land use, and perhaps the shorter winters.
• Scenarios for the future.
Overview of Main Points 1. Climate is changing globallyand in our region.
2. Impacts have already occurredand will get worse.
3. Emissions of greenhouse gasesespecially CO2 contribute to these changes.
4. Actions taken now can reduce the most severe future impacts
Ways to Think about UncertaintyUncertainties will continue to change.
Do and apply science.
Risk averse versus risk prone behavior.
Do right thing regardless.
Preserve future options.
All decisions are long term.
Reflect on other Issues for wisdom.
How Do Natural and Social Scientists Deal with Uncertainty
Kai Lee 1993. Compass and Gyroscope
Compass = Science and its Idealistic Application in Adaptive Management.
Gyroscope = Bounded Conflict as a Pragmatic Application of Politics Disciplines the Discord of Unavoidable Error.
Magnuson 2003
What to do?Relevant Time Scales
are Long Term.• Include Climate Change and Variability in planning and making decisions concerning natural resources, agriculture, energy production, cities, and other activities.
• Reduce greenhouse gas emissions in all sectors.
Preferences about OutcomesAgree Disagree
Beliefsabout
Causation
Agree
Computationin
BureaucraticStructure
Bargainingin
RepresentativeStructure
Judgment in
CollegialStructure
Settling
Consensus Building
Disagree Conflict
Kai Lee (modified from Thompson and Tuden 1959)