Methane release related to retreat of the Svalbard-Barents Sea Ice Sheet

Transcription

1 Methane release related to retreat of the Svalbard-Barents Sea Ice Sheet Karin Andreassen*, Alun Hubbard, Henry Patton, Pavel Serov, Sunil Vadakkepuliyambatta, Andreia Plaza-Faverola, Monica Winsborrow *Director of CAGE CAGE Centre for Arctic Gas Hydrate, Environment and Climate, Department of Geoscience, UiT- The Arctic University of Norway, Tromsø, Norway Presentation at Svalbard Science Conference 7. November 2017 cage.uit.no

2 Message Evidence for two modes of methane emissions from the Barents Sea area Andreassen et al Science Slow and steady release of gas bubbles (gas flares in the water) Eurasian Ice Sheet Complex ca 20 ka Massive, large-scale abrupt methane ejections related to retreat of the Svalbard Barents Sea Ice Sheet, evidenced by giant craters Image: Plaza Faverola Patton et al Reviews of Geophys, 2016, 2017 QSR

3 Outline of talk ❶ Motivation for the study ❷ Methods / work in CAGE ❸ Results ❹ Summary ❺ Why is this important Image: Plaza Faverola

4 1. Motivation Arctic continental shelves and land areas host vast amounts of methane trapped within permafrost and hydrates Gas hydrate: ice-like solid mixture of gas and water Water molecule forming a cage Gas molecule (e.g. methane)

5 Sustained warming in the Arctic has increased the awareness that future thawing of these shallow methane reservoirs could affect the climate and environment Gas hydrate: ice-like solid mixture of gas and water Water molecule forming a cage Gas molecule (e.g. methane)

6 Gas hydrates form under high pressure and low temperature Polar areas, e.g., permafrost (low temperature) Continental margins (high pressure)

7 CAGE - Centre for Arctic Gas Hydrate, Environment and Climate : 4 ~ 60 scientists How much carbon is stored in methane hydrate and free gas reservoirs in the Arctic, and how much of it is susceptible to climate change Processes and rates of methane expulsion from sub-seabed reservoirs to the ocean and atmosphere

8 We use cross-disciplinary methods and technologies to investigate Arctic methane hydrate systems through time ATMOSPHERE Methane emissions from the Arctic Ocean - MOCA (NILU) WATER COLUMN Mapping and quantification of released gas SEABED Bentic faunal response to methane release SUB SEABED RESERVOIRS Methane hydrate and free gas reservoirs PALEO-METHANE HISTORY Dating and investigating previous gas releases (NGU) Paleoceanography, Past methane, ocean acidification and CO2 The role of ICE AGES Interaction between ice sheets and gas releases

9 Use state-of-the-art technology in data acquisition System for acquisition of 3D seismic data from the subsurface P-Cable 3D seismic system Norwegian national infrastructue 9

10 Seafloor observatories K-Lander 30 observatory 10

11 National and international cooperations Seabed campaigns Gas hydrate pingos south of Svalbard investigated

12 National and international cooperations Sea - atmosphere campaigns

13 International cooperations Vestnesa Ridge gas hydrate drilling reached 70mbsf

14 RV Kronprins Haakon RV Helmer Hanssen

15 Gas hydrate pingos: among the hydrate systems most vulnerable to climate warming CAGE Centre for Arctic Gas Hydrate, Environment and Climate Serov et al PNAS 15

16 Over 100 giant craters and over 20 mounds in an area of 440 km2 Andreassen et al Science 2

17 2. Methods Cross-disciplinary investigations Geophys/geol/geochem data from the subsurface, seafloor and water column Numerical modelling of the hydrate stability zone, over the past 30,000 years

18 The Barents was covered by a 2 thick grounded ice sheet at the Last Glacial Maximum Patton et al Reviews of Geophys, 2016, 2017 QSR 18

19 Glacial and isostatic constraints are necessary for understanding hydrate evolution today subglacial Patton et al Reviews of Geophys, 2016, 2017 QSR

20 Conceptual model for formation of giant gas hydrate mounds and craters Andreassen et al Science Explosive gas ejections after the ice sheet retreated

21 4. Summary Two modes of gas emissions from the seafloor Slow and steady release of gas bubbles Massive and abrupt expulsions of pressurized gas form massive blow-out craters as gas hydrate decompose after ice sheet retreat

22 5. Why is this important? Abrupt methane expulsion from giant gas-leaking gas hydrate mounds Gas hydrate pingos in the Barents Sea will collapse in a warming future

23 5. Why is this important? Abrupt methane expulsion from giant gas-leaking gas hydrate mounds likely widespread across past glaciated petroleum provinces analog for future gas hydrate destabilization beneath and in front of contemporary retreating ice sheets Andreassen et al Science

24 CAGE Centre for Arctic Gas Hydrate, Environment and Climate is supported by the Research Council of Norway through its Centres of Excellence funding scheme grant 287 no Thank you for your attention! Visit us at: cage.uit.no