Norsk-amerikansk forskningsekspedisjon på innlandsisen i Antarktis. Kirsty Langley Norsk Polarinstitutt

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1 Norsk-amerikansk forskningsekspedisjon på innlandsisen i Antarktis Kirsty Langley Norsk Polarinstitutt

2 The Antarctic ice sheet Area: ca km 2 90 % of Earth s s ice Complete melting: 60 m sea-level rise! => Mass balance Steig et al. 2009

3 Background: Antarctica s role Antarctica s mass balance in climate change still not clear today Davis et al., 2005: increase of elevation ( ) 2003) Monaghan et al., 2006: no change of snow-accumulation rates ( ) Question: Mass balance of the (East) Antarctic ice sheet?

4 Background: Field data from Antarctica Vaughan, 1999 Lythe, 2000 Uncertainties from remote sensing signatures Few ice cores from East Antarctic interior Traverse route Large areas of bed still unmapped Filling in large data gaps across East Antarctica

5 Overarching science questions: (1) Understand climate variability in Dronning Maud Land of East Antarctica on time scales of years to one millennium. (2) Determine the mass balance of the ice sheet in this sector to understand its impact on sea level change. (3) Investigate the impact of atmospheric and oceanic variability on the chemical composition of firn and ice in this region. (4) Revisit areas and sites first explored by traverses in the 1960s, for detection of possible changes, and to establish benchmark datasets for future research efforts.

6 Planning and Preparations Practical and safety issues whilst maintaining flexibility Oct Troll 16. Nov leave Troll 14. Jan arrive C. Winter 20. Jan arrive S. Pole 23. Jan arrive McMurdo 26. Jan arrive NZ Nov McMurdo 12. Dec S.Pole 23. Dec leave S.Pole 21. Feb arrive Troll 26. Feb arrive CapeTown

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8 Photo s: Stein Tronstad

9 Helgard Anshuetz, Elisabeth Issaksson, Joe McConnel, Ross Edwards, Zoe Courville, Mary Albert, Tom Neumann What is the accumulation rate in East Antarctica, and has it changed in recent decades? Measurements: snow & firn physical and electrical properties, and chemical dating 80 m 30 m Total ice core: 30 m 25 m 90 m 30 m 13 m 2x30 m 90 m 19 m 25 m 22 m 90 m 20 m 90 m 2007/08 ~ 700 m 2008/09 ~ 500 m Stein Tronstad Atsu Muto What regional climate patterns are evident over the last 1000 years? Measurements: chemical & isotopic composition of ice cores

10 Post processing of cores at NP, Tromsø and DRI, Nevada Chemical analysis Electric and conductive properties Photos s: Helgard Anshuetz

11 Anna Sinisalo, UiO Hubra, GHz Karsten Muller, Anna Sinisalo, Gordan Hamilton, Tom Neumann What is the accumulation rate in East Antarctica, and has it changed in recent decades? Continuous measurement of layers, calibrated with cores gives average accumulation MET + GPS + GPR => how temperature, elevation and topography effect snow accumulation and distribution in East Antarctica. Stein Tronstad Karsten Müller, UiO C-band, 5.3 GHz

12 Kirsty Langley, Jack Kohler, Ted Scambos What is the ice thickness and structure of the bed? Is there any water present? Continuous measurement of ice thickness and internal layers, point gravity readings Stein Tronstad

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14 Atsu Muto, Ted Scambos What is the thermal response of East Antarctica to global warming? Past (30~50 years): Firn temperature profiling 0.15 m 0.65 m 1.65 m 2.65 m 3.15 m The most recent ~15 years on average is warmer by ºC However, difficult to say whether it is from 50 years ago or 100 years ago Reconstructed surface temperature indicates warming trend near the divide of East Antarctica for the Infer 2 m past multi-decadal several decades scale surface temperature trend in Need additional data to further inverse method constrain the trend (reanalysis data, ice cores 5??) m 10 m 16 m 23 m 32 m 40 m 55 m 70 m 90 m temperature deviation from 99 years ago (ºC) Objective Make firn temperature profile measurements with a simple system suited for traverse set-up Inverted Surface temperature histories in East Antarctica 90 the inland of East Antarctica, using the geophysical time (years BP)

15 Results so far Revisiting sites of the South Pole Queen Maud Land Traverses (SPQMLT) in East Antarctica: accumulation data from shallow firn cores H. Anschuetz et al. In Press: JGR Tambora/1809 as time marker Influenced mainly by elevation and continentality 3 cores: : > 20% decrease in 19th+20th century An 860-km accumulation rate profile on the East Antarctic Plateau derived by GPR Karsten Muller et al. Under review: Ann. Glac. Mean accumulation rate over last 200 years using Tambora (1815) marker. Either recent increase in accumulation rate Or Overestimation by up to 50 % by previous studies

16 Norwegian Polar Institute Research Council of Norway Acknowledgements US National Science Foundation Crews at Troll, Amundsen-Scott and McMurdo Stations Traverse teams 2007/08 and 2008/09