Connections Between West Antarctic Ice Core Sulfate and Climate Over

the Last 200 Years

Daniel A. Dixon, Paul A. Mayewski, Susan Kaspari, Karl Kreutz, Gordon Hamilton, Kirk Maasch, Sharon B. Sneed and Michael J. Handley

Climate Change Institute, Department of Earth Sciences, University of Maine, USA

ACKNOWLEDGEMENTS: Office of Polar Programs, National Science Foundation, 109th Air National Guard, Ice Core Drilling Services, Raytheon Polar Services.

RESEARCH QUESTIONS

● Has sulfate deposition remained stable across West Antarctica for the last 200 years?

● Have anthropogenic emissions affected West Antarctic sulfate concentrations in recent decades?

● Do sea ice extent fluctuations affect sulfate concentrations across West Antarctica?

ICE CORE LOCATIONS

Map created using the RAMP DEM (Liu and others, 2001).

MAJOR ION SOURCE CHEMISTRY

(modified from Oeschger, 1982)

(Na + NH4 + K + Mg + Ca) + (Cl + NO3 + SO4) = 95% of Dissolved Ions(Also test for MS - Biological Signal)

CATIONS (+) ANIONS (-)

ICE SHEET

(Na + K + Mg + Ca) + (Cl + NO3 + SO4) = 95% of Dissolved Ions(Also test for MS – Biological Signal)

(Separated into xs and ss SO4)

MAJOR ION SOURCE CHEMISTRY

sea salt

?

RESEARCH QUESTIONS

● Has sulfate deposition remained stable across West Antarctica for the last 200 years?

RAW xsSO4 (RED) AND ssSO4 (GREEN)CONCENTRATIONS FROM 1800-2002 AD

RAW xsSO4 (RED) AND ssSO4 (GREEN)CONCENTRATIONS FROM 1800-2002 AD

ROBUST SPLINE SMOOTHED ANNUAL xsSO4 CONCENTRATIONS (in ppb)

ICE CORE LOCATIONS

Map created using the RAMP DEM (Liu and others, 2001).

RESEARCH QUESTIONS

● Have anthropogenic emissions affected West Antarctic sulfate concentrations in recent decades?

NORTHERN HEMISPHERE (GISP2) SULFATE RECORD

(Data for this figure provided by Dr. Paul A. Mayewski)

ROBUST SPLINE SMOOTHED ANNUAL xsSO4 CONCENTRATIONS (in ppb)

RESEARCH QUESTIONS

● Do sea ice extent fluctuations affect sulfate concentrations across West Antarctica?

SDM-94 xsSO4 and Sea Ice Extent

Sea Ice Data From SIMMONDS AND JACKA (1995)

SDM-94 xsSO4 and Sea Ice Extent

LINEAR CORRELATIONS BETWEEN ANNUALLY AVERAGEDSEA ICE EXTENT AND xsSO4 CONCENTRATIONS

High xsSO4 ConcentrationsAssociated with DecreasedSea Ice Extent.

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+

-- -

+

++

+

All Values Above95% Significant

(r ≥ 0.414)

Latitudinal positionof labels has no

significance

+

-

-

-

-

+

-

-

-High ssSO4 ConcentrationsAssociated with IncreasedSea Ice Extent.

All Values Above95% Significant

(r ≥ 0.405)

LINEAR CORRELATIONS BETWEEN ANNUALLY AVERAGEDSEA ICE EXTENT AND ssSO4 CONCENTRATIONS

Latitudinal positionof labels has no significance

CONCLUSIONS

● A climate transition affects Central West Antarctic sulfate concentrations around 1940.

● There is no compelling evidence for anthropogenic impact on Antarctic SO4 concentrations.

● When sea ice extent is increased (decreased), ssSO4 (xsSO4) concentrations are higher.

Thank You For Listening…