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The Impacts of large scale climate variability on Northwest climate
and salmon
Nate Mantua, Ph.D.
Climate Impacts Group
University of WashingtonPortland, OR September 21, 2004
Warm and cool (or “wet” and “dry”) halves of the year: oct-mar versus apr-september
NW climate varies over multiple time frames:• year-to-year• decade-to-decade• century long trends
El NiñoEl Niño
La NiñaLa Niña
Equatorial Ocean Temperature deviations from the long-term average: 1982-September 2004
82/83
86/87/88 91/92
97/98
02/03
ENEN93
94/95
LNLN
Coastally trapped internal ocean waves from the tropics
El Niño/La Niña and NW salmon habitat
El Niño winters:• intense Aleutian Low
low streamflows• weak trade winds,
coastally trapped warm water currents
• warmed, strongly stratified upper ocean
La Niña winters:• weak Aleutian Low
high streamflows• intense trade winds,
coastally trapped cold water currents
• cooled, weakly stratified upper ocean
The Pacific Decadal Oscillation
• an El Niño-like pattern of climate variability
• 20 to 30 year periods of persistence in North American and Pacific Basin climate
• warm extremes prevailed from 1925-46, and again from 1977-98; a prologed cold era spanned 1947-76
• mechanisms and mechanisms and predictability arepredictability are unknownunknown
19991925 1947 1977
Annual Temperature Trends, (°C / century) 1901-1999
Source: P. Jones, et. al. 2000.
PNW average PNW average temperatures temperatures have risen have risen +1.5F/century+1.5F/century
decrease increase Trends in April 1 Snowpack
(“snow-water-equivalent) 1950-2000
Relative to 1950 value
73% – trends Large – trends PNWSome + trends SW
Image courtesy of Phil Mote, UW Climate Impacts Group
As the West warms,winter flows rise and summer flows drop
Figure by Iris Stewart, Scripps Inst. of Oceanog. (UC San Diego)
NE Pacific Salmon Fishery Production (millions)
0
100
200
300
1910 1920 1930 1940 1950 1960 1970 1980 1990
Pink
Sockeye
Chum
Coho
Chinook
Total Salmon Fishery Production by Region (millions)
0
100
200
300
1910 1920 1930 1940 1950 1960 1970 1980 1990
Year
Alaska
BC
WOC
A North-South Inverse Production Pattern
PC scores
34% variance
Mantua et al 1997
Hare, Mantua, and Francis 1999 Gargett 1997“Optimal Stability Window”
r(pdo) = .73r(niño34) = .53
OPI (hatchery) coho marine survival
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 19901992 1994 1996 1998
Return Year
Survival
Why? Leading hypothesis: changes in ocean conditions impact the entire marine food-web
upwelling food webs in our coastal ocean: the California Current
Cool water, weak stratificationhigh nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators
Warm stratified ocean, fewnutrients, low productivity “subtropical” food web, a lack of forage fish and abundant predators
Upwelling impacts: August 2000
temperature Chlorophyll
For the NW coastal ocean, spring/summer upwelling is a key and highly variable process that structures the coastal ocean food web
ColumbiaColumbia RiverRivermouthmouth
Sept 1997 El NiñoSept 1997 El NiñoSept 1998 La NiñaSept 1998 La Niña
Environmental variability can be large
“Newport Line” (central Oregon coast)upper ocean temperatures
Dep
th in
met
ers
A thick layer of warm (low density) water at the surface can cut off the nutrient supply…
Upwelling without nutrients yields no benefits to phytoplankton!
April 1983April avg1962-71
Newport Line temperatures at depth: from hot to cold
April1998
April1999
April1983
April1962-71
Figure obtained from:http://ltop.coas.oregonstate.edu/~ctd/
1000 smolts 10’s to 100’s post-smolts early summer
A few to ~100 adults in 2nd summer
key factors? •Stratification •spring transition date•spring winds, upwelling and transport
?
1st s
prin
g at
sea
1st w
inte
r at
sea
key factors? •Stratification •winter winds, downwelling and transport
?
coastal ocean impacts on coho marine survival (Logerwell et al. 2003, Fish. Oceanogr.)
4 index Ocean Conditions Model “hindcasts” for OPI coho marine survival, 1969-1998
Logerwell et al. 2003, Fish. Oc.
R2= .75
“Ocean Conditions Model” hindcasts for 1948-1968
Washington-Oregon-CaliforniaWashington-Oregon-Californiacoho landingscoho landings
Cat
ch in
mil
lion
s of
coh
oC
atch
in m
illi
ons
of c
oho
2
4
6
OP
I survival rate (%)
2
4
6
8
10
Ocean conditions appear to be an important piece of the OPI hatchery coho story; they may or may not explain an important part of 48-68 coho landings.
Life Cycle Modeling for NW coho(Lawson et al. 2004, CJFAS)
• Link climate impacts on life cycle survival rates in both freshwater and marine environments– For Oregon coast coho “good”
stream conditions are correlated with “good” ocean conditions
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
summary• NW climate varies in part due to the influences of
El Nino/La Nina, PDO, and global warming– Other causes remain unnamed, some of which are not
likely predictable
• NW salmon are clearly sensitive to climate induced changes in stream and ocean conditions– changes in NW climate can cause simultaneous
negative or positive impacts in stream and ocean conditions
• warmer temperatures are typically bad news in both environments, cooler temperatures are typically good news
• Future climate isn’t likely to be like past climate– we are developing tools to examine the hydrologic
impacts of climate warming
Recent climate events
A North-South see-saw in salmon production
Warm PDO Cool PDO Warm PDO ???Cool PDO
spri
ng
chin
ook
ret
urn
s to
th
e C
olu
mb
ia R
iver
mou
th
(100
0s)
Alask
a pin
k an
d sock
eye catch
(million
s)
Wintertime SST anomaly patterns:
• from 1990-97, a warm north Pacific did not match the PDO pattern of the past
• cooler period from 1999-2002 also differed from PDO pattern
1990-97
1999-02
2003
Ocean temperature anomaliesAugust 15-September 11, 2004
August 2004 ocean
temperatures
OPI coho GAM data for 2004 smoltsC
oho
SA
RC
oho
SA
R
JFM 2004 JFM 2004 SST =10.5CSST =10.5C
SpTr 2004SpTr 2004Day 109Day 109
Neah Bay Neah Bay SL=-117mmSL=-117mm
JFM 2005 JFM 2005 ~ 10-11 C?~ 10-11 C?
Looking to the future…
• “global climate system models” now used to assess the impacts of human activities on Earth’s climate– Similar to the computer models used to predict
the weather, but much more sophisticated– simulate interactions between the atmosphere,
its constituents (C02, O2, O3, N2 …), the ocean, sea ice, vegetation, and clouds
Northwest warming
7
8
9
10
11
12
13
1900s1910s1920s1930s1940s1950s1960s1970s1980s1990s2000s2010s2020s2030s2040s
Degrees C
warmest scenarioaverage coolest scenarioobserved
~1.5 to 3°Cor~ 3 to 6 °Fwarmer in the 2040’s
Most models also simulate slightly wetter winters
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