1. University of Washington, Seattle WA
Decades long El Niño-like climate variations: the Pacific Decadal Oscillation and its impacts on marine and terrestrial systems
Nate Mantua
Climate Impacts Group
University of Washington, Seattle WA
October 21, 2003, UC Berkeley

2. Outline PDO signatures in Pacific/N. American climate
impacts on forests and marine ecosystems
paleoclimate evidence
mechanisms and predictability

3. 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
PDO fingerprints found in records of temperature, precipitation, snow pack, streamflow, and marine ecosystems
1998?
1947
1925
1977
Mantua et al. 1997: A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production, Bulletin of the American Meteorological Society, Vol 78, p

4. PDO research ...
Both climate and fisheries research are behind this story
Ebbesmeyer et al’s “1977 Regime Shift”
A step change in 40 environmental parameters in the Pacific (1991)
Nitta and Yamata 1989, Tanimoto et al 1993, Graham 1994, Trenberth and Hurrel 1994, Kawamura 1994, Latif and Barnett 1994, Miller et al 1994, Zhang 1996, Zhang et al 1997, Mantua et al 1997, Minobe and many more have followed

5. “1976 Step in Pacific Climate: 40 environmental changes …” (Ebbesmeyer et al. 1991, PACLIM proceedings)
Large and local scale climate indices, Canadian geese, NW salmon, dungeness crab, Pacific sea birds numbers, Washington Oyster growth … all folded into a 40-member composite variable.
(see Kerr, Science Vol 255, 1992)

6. PDO research at the University of Washington
A product of 3 semi-independent streams of research
Hare and Francis (1992), UW Fisheries Research Institute: North Pacific climate and year boom/bust cycles in Alaska salmon
Zhang and Wallace (1994), UW Atmospheric Sciences: Ocean/Atmos variability in Pacific climate, ENSO vs North Pacific Climate Variations
Mantua (1995), UW Climate Impacts Group: Pacific Northwest “climate history”, climate impacts on NW salmon

8. Oct-March Sea Level Pressure anomalies during
warm phases of PDO: an intensified Aleutian Low L H H
Contours every .5 mb

9. 500 mb height anomalies during warm phases
of PDO: the Pacific North America pattern H L H
Contours every 5 meters

10. October-March PDO Regression fields
Surface Air Temperature
Precipitation
Figures produced by Todd Mitchell, UW/JISAO

11. Regional Indicators for PDO variability (Mantua et al 1997, BAMS)
Gulf of Alaska winter air temperature
BC Coastal SST
Regional Indicators for PDO variability (Mantua et al 1997, BAMS)
Scripps Pier SST
1925
1947
1977
Kenai River Streamflow
BC/Washington Streamflow

12. PDO and North American Climate
Warm PDO: ; (?)
Cool PDO: ; ;
winter and spring time temperatures: relatively warm in northwest North America, and cool in the southeast
winter and spring time precipitation: wet in the southern US and northern Mexico, and dry in the Pacific Northwest and Great Lakes regions
winter and spring time temperatures: relatively cool in northwest North America, and warm in the southeast
winter and spring time precipitation: dry in the southern US and northern Mexico, and wet in the Pacific Northwest and Great Lakes regions

13. PDO impacts on western forests

14. Snowpack, PDO and tree growth
Mountain hemlock in the Cascade
and Olympic Mountains
high elevation OR/WA Mt Hemlock and snowpack
Deep snowpack
Low snowpack
low elevation OR/WA Mt Hemlock and pdo
warm/dry
warm/dry
Cool/wet
From Peterson and Peterson (2001)

15. Years with fires > 80,000 ha Fires in national forests, 1916-1997
From Mote et al. (1999)

16. PDO impacts on marine ecosystems

17. Alaska Commercial Salmon Catches 1878-2001
Alaska Department of Fish and Game

18. Bottom trawl surveys in Pavlov Bay, Alaska 1970’s
(source: Botsford et al. 1997, Science, 277: )
1970’s
1980’s

19. A history of change from a 50 year record of Gulf of Alaska bottom trawl surveys
The ecosystem impact of the much discussed North Pacific regime shift is perhaps best captured by a time series of small mesh bottom trawl surveys
From: Anderson and Piatt (2000) Mar. Ecol. Prog. Ser 189:

20. Pacific salmon catch data analysis (Hare, Mantua and Francis 1999, Fisheries)
Combine commercial+sport+subsistence catch from
assume that catch reflects abundance
apply “regional normalization”
focus on critical period by shifting each record in time to reflect typical year of ocean entry (chinook & chum 3 years, sockeye 2 years, coho and pink 1 year)

21. An Inverse Production Pattern
34% variance
Hare, Mantua, and
Francis 1999, Fisheries Vol 24: 6-14
PC scores
r(pdo) = .73
r(niño34) = .53

22. Why an inverse production response to PDO/ENSO-related variability?
H1: “optimal stability window” and “bottom up” impacts on marine food-webs
Gargett 1997, Fisheries Oceanogr. 6:
Phytoplankton
production N S
Stratification or upwelling

23. Empirical Evidence for N. Pacific Regime Shifts in 1977 and 1989
Other coherent patterns in marine ecosystems?
Empirical Evidence for N. Pacific Regime Shifts in 1977 and 1989
Hare and Mantua, Progress in Oceanogr. 2000, 47:

24.
: PC1
: PC2
Hare and Mantua, Progress in Oceanogr. 2000, 47:

25. Paleoclimate reconstructions

26. Tree-ring based PDO index reconstructions: (ex: Gedalof and Smith 2001, Geophys. Res. Letts. 28: )
Plots courtesy of Torrence and Compo

27. Geoducks:
“gooey duck”,
Panopea abrupta
geoduck shells may have the tree-rings of the extratropical seas

28. Thin section of geoduck shell from Protection Islandx
warm PDO
cool PDO
1969
1998
1978
Are Strom, 2003 M.Sc., UW School of Fisheries

29. Ocean temperature reconstruction based on Protection Island geoduck growth rates
Growing season (March-October) temperatures x x x
The geoduck is found throughout the north Pacific, from San Francisco to Alaska and from eastern Russia to Japan. This reconstruction is based on clams dug near Protection Island, just outside of Discovery Bay in the eastern part of the Strait of Juan de Fuca. The longest-lived geoduck in the collection was 160 years old, and fossil clam shells offer the potential for reconstructing climate much deeper into the past.
Are Strom, 2003 M.Sc., UW School of Aquatic and Fishery Sciences

30. Paleo-salmon abundance estimates from lakebed sediment cores (Finney et al. 2000, Science 290: )
Figure 4. Comparison of 15N profiles from sockeye and control lakes from the Kodiak Island and Bristol Bay regions of Alaska over the past ~300 years (upper two panels). The sockeye lake profiles have many common trends in 15N, including lower values in the early 1700s, early 1800s, and the mid- to late 1900s. The two control lakes (Frazer and Tazimina) are similar to the sockeye lakes in morphometry and geography, but have waterfalls at their outlets impassable to sockeye. However, the construction of a fish ladder over the Frazer River waterfalls in the 1950s has allowed the migration of sockeye into this lake, and the associated SDN loading is faithfully tracked by the recent 15N enrichment in the Frazer Lake sediment profile. The lower panel compares 15N anomalies of the composite sockeye lake record with a reconstruction of Gulf of Alaska sea surface temperature (SST) (25) over this period. The composite sockeye lake record (calculated as the average deviation from the record mean of each of the five sockeye lake profiles) highlights the consistency of the variation in the sockeye lakes' 15N profiles. The SST reconstruction for the Gulf of Alaska (25-year smoothed) is based on coastal tree-ring data.
Impacts of Climatic Change and Fishing on Pacific Salmon Abundance Over the Past 300 Years. Bruce P. Finney, Irene Gregory-Eaves, Jon Sweetman, Marianne S. V. Douglas, John P. Smol, 2000.
1700
1800
1900
2000

31. Using PDO information in Climate Predictions

32. ENSO/PDO combined influences on North American
Climate (JFM precipitation)
warm PDO/La Niña
cool PDO/La Niña
Gershunov, Barnett
and Cayan 1999 Eos Transactions

33. Columbia River summer (April-September) streamflow
} ~ 20%
change
Alan Hamlet and Dennis Lettenmaier, UW Civil Engineering

34. PDO Predictability PDO mechanisms will define its predictability
best case scenario:
slow ocean adjustment+air/sea coupling (like El Niño)
Worst case scenario:
ocean adjustment to surface fluxes is purely via mixed-layer heat storage -- this would limit predictability to ~ 1 year
atmosphere
ocean
Re-emergence in entraining mixed layers
Deser et al. 2003, J. Climate 16:57-72

35. PDOforecastn = *PDOobservedn-1 +*ENSOn + oisen
ENSO-forced variability of the PDO Newman et al. J. Climate Letters (in press)
PDO variability reflects a “reddened” response to atmospheric “white noise” and ENSO forcing (at all time scales)
The basic model:
“the PDO is simply due to reemergence + ENSO forcing + random atmospheric forcing”
PDOforecastn = *PDOobservedn-1 +*ENSOn + oisen

36. Simple model performance Newman, Compo and Alexander (in press) J
Simple model performance Newman, Compo and Alexander (in press) J. Climate Letters
Forecast vs. Observed
Annual PDO (July-June)
1 year lead time hindcasts vs Observed correlations
Modeled time series power spectra not as “red” as observed PDO
Prediction for July-June 2004? ~ to +1
Full model
R = .74
Ignore ENSO
R = .53
ENSO only
R = .54
1900
1950
2000
Power Spectra
RMS forecast Errors are ~ 20% lower for full model compared to other models
Observed
forecast
Period

37. Now-casting assessing the current status of the PDO is difficult:
what should we be tracking????
El Niño experience tells us that improved understanding will come with improved measurements, diagnostics and modeling

38. Keeping track of El Niño/Southern Oscillation: the TAO/TRITON array
The backbone of today’s ENSO Observing Network
initiated in 1985, completed in 1994
70 moored buoys provide real-time in-situ surface and subsurface conditions (winds, temperatures, currents)

39. ARGO: the latest addition to a global ocean observing system

40. Summary
over the past few centuries PDO has been an important pattern of climate variability at periods comparable to a human’s life time
provides insights into the history of water and fishery resources: can we learn from this history?
offers another avenue for improving climate predictions at the seasonal and (potentially) multi-year time scales
fisheries and climate research communities putting lots of effort into learning more about PDO and its impacts

41. upwelling food webs in our coastal ocean: the California Current
Cool water, weak stratification
high nutrients, a productive “subarctic” food-chain with abundant forage fish and few warm water predators
Warm stratified ocean, few
nutrients, low productivity “subtropical” food web, a lack of forage fish and abundant predators
For the California Current, the broad upwelling ecosystem off the coast of southern British Columbia south to the US/Mexico border, climate variations appear to influence the entire food web. The left panel of this schematic depicts a cool, weakly stratified upper ocean. Nutrients are easily upwelling into the surface layer, and these conditions coincide with a highly productive subarctic food web. Predation pressure on juvenile salmon (smolts) is slight, in part because of an abundance of other smolt-sized forage fish (herring and anchovies) and a relative lack of migratory predators like hake and jack mackerel. The net result is high smolt survival and excellent feeding conditions for maturing salmon.
In contrast, warm periods bring a sharply stratified coastal ocean which inhibits the upwelling of deep nutrient rich water, thereby limiting phytoplankton productivity. The warm water eras also see a dominance of “subtropical” zooplankton species, a relative lack of forage fish, and an influx of warmwater predators like hake and jack mackerel that are typically found to the south or in offshore waters. The net result is poor smolt survival due to intense predation pressure (by fish and diving birds), as well as poor growth for maturing salmon.
Abundant Krill!
Krill are in short supply