# Presentation: 855510

## Is the Bering Sea Stuck in a Warm Phase?

**Jim Overland**
**NOAA/PMEL/FOCI**
- J. Boldt, A. Hollowed, P.Stabeno, G. Hunt Jr., Muyin Wang

## Bering SeaClimate Indices

** ****Grey - Lowest 1/3**** ****Pink  - Middle 1/3**** ****Red  - Highest 1/3**

- 1965                        1975                        1985                         1995

- Bering SeaClimate Indices

## Slide 3

## Slide 4

## Summer (July 15 – Sept 15) Ocean Heat Content

- Summer (July 15 – Sept 15) Ocean Heat Content
- at Mooring 2 (56.8N, 164W)

## Vertically Averaged Temperature (°C) at Site 2

## 
Minimum Summer Arctic Ice Extent

**Minimum Summer Arctic Ice Extent**

***Climate and Ecosystems***

## Percentage of ice cover during winter 2004 for 56-58oN, 163-165oW

## Ice, Bloom, and Copepods

**Late Ice Retreat****	****	****           ****Early Bloom, Cold Water – Small Copepod Biomass**

**Ice, Bloom, and Copepods**

## Dendogram of Bering Sea stocks based on hierarchical cluster analysis of pairwise Manhatten distances among standardized recruitment

- From  Franz Mueter & Bern Megrey

## Three different responses

**Three different responses**
**to the 1977 regime shift**

## Benthic Changes

**Benthic Changes**

## Long-term Observatory maintains sites south of St. Lawrence Island

-   overall decline late 1980’s to 1998, then level out in both sediment oxygen uptake (indicator of carbon flux to sediments) and overall benthic standing stock
-   retrospective study indicates changes in dominant bivalve from *Macoma calcarea* to *Nuculana radiata*

**Long-term Observatory maintains sites south of St. Lawrence Island**

- [Simpkins et al., Polar Biology, 2003]

## Walrus herd in the Chukchi Sea– June 2002

- [M. Webber-USFWS]

- Schematic of food web in the northern Bering and Chukchi Seas
- [Grebmeier and Dunton 2000]

- Clam food in walrus stomachs

- [photos courtesy G. Sheffield]

## Northern fur seal pups born on Pribilof Islands

- St. Paul

- St. George

- Error bars are 95% confidence intervals

- http://nmml.afsc.noaa.gov/alaskaecosystems/nfshome/survey2004pribpups.htm

## Bering Sea Pollock 

## Pollock and Bottom Temperature

- 0.0           0.25         0.50        0.75         1.0

- Relative CPUE

- 170oW                    170                        165                     160oW

- 60oN

- 58oN

- 60oN

- 58oN

- J Ianelli

*Hunt et al., 2002*

- Oscillating Control Hypothesis

## Surface Temperature:  1-January-1975

**Bering Climate**
**Cold/dry Arctic air mass-Warm/moist Pacific air mass**

## Bering Climate was

- Location of Surface Stations

- St. Paul -Barrow

- St. Paul - Nome

- Running Correlation of Winter Surface Air Temperature
- Between Stations With 25 yr Window Length

- Probability Distribution of the Difference Between Max and Min Running Correlations

- different before 1970

## Arctic Changes

- Permafrost degradation on the Tanana Flats
- Jorgenson et al., 2001, Climatic Change

- Sea Ice

- Sept 2003

## Bering Sea Summary

- Switched from long-term (170 yr) stable cold Arctic ecosystem to sub-Arctic ecosystem after 1976
- Last four years:  Continued warm ocean and atmosphere; little or no ice in south Bering
- Stuck in “warm phase” due to Arctic climate change? Favor pollock over Arctic species? Top-down?
- Ocean observing mooring(M2) important to confidence in result of recent change

## Depth-Averaged Temperature in the SE Bering Sea

## Slide 24

## Slide 25

## Mooring Sites

**Notes:**
How will NPCREP enhance societies ability to plan and respond to climate variability or change?  We will look at four strategies:
The first is observation.  Observing systems are part of the foundation for ecosystem approach to management and to determine how climate impacts that ecosystem..
In 2005, in conjunction with a state of Alaska research program, we plan to expand a series of biophysical moorings along the middle shelf of the Bering Sea.  In addition we will initiate a spring biophysical survey of the shelf. Show in the figure on the left.
 In collaboration with fisheries we will initiate a summer plankton survey.  The grid of the survey is shown on the right.
Long term observations are critical to understand how climate is changing and how it impact the ecosystem

## Pollock Recruitment with

**Pollock Recruitment**** ****with**
**Summer Wind Mixing**** ****&**** ****Winter Surface Temperature**

- 1978

- 1996

- 1982

- 1989