the impacts of large scale climate variability on northwest climate and salmon nate mantua, ph.d....

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