The Exploration of the Coastal Zone in the Arctic seas: Siberian Shelf Studies

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1 The Exploration of the Coastal Zone in the Arctic seas: Siberian Shelf Studies V.I. Sergienko, FEBRAS NEESPI Summit Helsinki, Finland May 3-4, 2007

2 SCIENTIFIC MOTIVATION 1. Artic Ocean is small (~4% from total World Ocean), but it is unique because one is surrounded with onshore permafrost (upper 100m layer contains ~10,000Gt C) and underlain with offshore permafrost which contains a huge reservoir of organic matter and trapped methane, including methane in form of gas hydrates (up to 6,000Gt C); Arctic Ocean is the largest pool of organic carbon (including methane and oil) in the World Ocean 2. Area of permafrost (land and sub sea) of the adjacent Siberian Arctic seas (near 14 mln sq.km) is equal to the total area of Arctic Ocean; old carbon buried in permafrost is biodegradable. 3. Artic shelf is the broadest and shallowest shelf in the World Ocean and its coastal zone is the most strongly impacted by warming (possible consequences: degradation of permafrost, methane and carbon dioxide release into the atmosphere, seaward export of terrestrial organics).

4. It was supposed early that offshore permafrost is stable and may persist beneath any part of the Arctic shelves inshore from about the 90 m isobath T= 1.4 C T=0.

3 4. It was supposed early that offshore permafrost is stable and may persist beneath any part of the Arctic shelves inshore from about the 90 m isobath T= 1.4 C T=0.3 C But new data (ACIA, 2004) show that sub-sea permafrost completely (Barents Sea) or in part degraded in the Arctic shelf seas. Our initial data show island distribution of shallow sub sea permafrost: hollow circles indicate on existence of permafrost, while dark circles on lack of sub-sea permafrost (Iossoupov, Salomatin, Semiletov, DAN, 2005).

4 Basic scientific question are: 1. What is a role of changing offshore and onshore permafrost in carbon cycling in past, present, and future 2. How the Arctic ocean-land carbon hyper pool may react on global warming and vice versa? 3. How to detect changes (freshwater, terrestrial carbon, eroded material storages and etc) in the Arctic land-shelf system? 8-10% High Latitude Antarctic Arctic Mid Latitude Pole-to-Pole gradient of CH 4 in the atmosphere is existing in warm climate stages, while it is negligible during cold epochs. Latitudinal distribution of methane in the atmosphere in present

5 To respond for these basic questions our group established multi-year bi-national cooperative study in the East-Siberian Sea and adjacent seas which represents the broadest and shallowest shelf in the World Ocean which is strongly impacted by global change (highest rates of coastal erosion and sea level rise, and etc) Novosibirsky Arc 75 N Laptev Sea East-Siberian Sea Wrangel Is. Chukchi Sea 70 N Tiksi Yana Indigirka 65 N Lena Yakutsk Mech. Kulibin (1995, 1999) Alpha Helix (1996) Dunay (1997) Cap. Ponomarev (1998) Dunay (1999) Nikolay Kolomeitsev (2000) Prof. Khromov (2002) Ivan Kireev (2003) Ivan Kireev (2004) Kolyma Chukotka Serdtse Kamen C. Bering Sea Alaska Ocean Data View 140 E 160 E 180 E 160 W The study area explored by FEBRAS in cooperation with IARC UAF from 1995 to Major studies in the East-Siberian Sea were performed in the joint Russia-US cruises (2003, 2004, 2005, and 2006) co-funded by NSF and NOAA from the US side, and by FEBRAS from the Russian side.

6 75 Laptev Sea 6 80 N N 76 N Tiksi Kara Sea Laptev Sea 74 N N 70 N 60 E 80 E 100 E 120 E Ocean Data View The study area Helicopter survey area is captured by red squire. We are working on linking marine and terrestrial measurements of major greenhouse gases: CH 4 and CO 2 (and water vapor) to study their fluxes across the air-water interfaces (dissolved CH 4 and carbonate system parameters were also measured). Eddy correlation (EC) technique was utilized using the 3D sonic anemometer, LiCor-7500 and DLT-100 sensors.

7 ONGOING AND PROPOSED RESEARCH We assume that during the Holocene and previous warm stages, the degradation of sub-sea and coastal/bottom permafrost (enriched by organic carbon), and possible disturbance of gas hydrates are the best coastal candidates to explain the resulting regional increase in the atmospheric CH 4 and CO 2. Therefore it is important to conduct the complex studies required to evaluate in a timely fashion how and when the near-shore permafrost carbon/methane bomb may explode before such a catastrophic event should occur. DRIVEN HYPOTHESIS Hypothesis 1. The Arctic sub-sea permafrost represents the largest carbon pool that might be involved in current biogeochemical cycling due to thawing of the permafrost and restoration of the activity of viable methanogens preserved in permafrost. Hypothesis 2. The Arctic Siberian coastal zone plays a significant role in the regional budget of CH 4 and CO 2 because changes in the current carbon stock of sub-sea and coastal/onshore permafrost might significantly affect the increase of CH 4 and CO 2 over the Arctic. Changes (freshwater, terrestrial carbon, eroded material storages and etc) in the coastal zone indicate on general changes in the land-shelf system. Hypothesis 3. Warming enhances export of terrestrial organic material into the sea, because increase in river runoff (DOC) and coastal erosion (POC/PM). Extended scientific output. Understanding the role of thawing sub-sea and coastal permafrost (and possibly decaying gas hydrate) in controlling air-sea CH 4 and CO 2 exchange, essential to advancing our understanding of the mechanism for atmospheric CH 4 and CO 2 maximum formation above the Arctic in

8 1. Glacial-Interglacial temperature rise is ~ 16 C which is enough to initiate degradation of sub-sea permafrost and underlain methane hydrates. Annual mean air temperature -17 C Annual mean bottom water temperature -1 C This feedback is a trigger to enhance degradation of subsea permafrost and consequent CH4 release on unprecedented scale. Huge amount of buried old carbon may be involved in modern biogeochemical cycles

76N 74N 72N 70N 68N 44 37 38 42 3940 41 43 7 6 5 4 8 36 9 10 35 11 12 34 15 14 13 18 19 20 21 22 32 31 23 145E 150E 155E 160E 165E 170E 175E 33 30 24 a) b) Preliminary results obtained in the coastal

9 76N 74N 72N 70N 68N E 150E 155E 160E 165E 170E 175E a) b) Preliminary results obtained in the coastal zone of the East-Siberian Sea in the joint IARC-FEBRAS cruises confirm our driven hypothesis (Semiletov et al., 2007; Shakhova and Semiletov, 2007; Pipko et al., 2005) Latitude Depth, m 74N 72N 70N 68N Latitude D Laptev Str. Indigirka 1 Novosibirskiye ostrova 2 Kolyma 145E 150E 155E 160E 165E 170E 175E Novosibirskie ostrova Indigirka Longitude S e a i c e E a s t - S i b e r i a n S e a Geographical location of the transect Kolyma -40 Longitude Distance, km nm nm c) Latitude 74N 72N 70N D Laptev Str. Novosibirskiye ostrova E a s t - S i b e r i a n S e a 4 5 Indigirka S e a i c e 6 nm N Kolyma 145E 150E 155E 160E 165E 170E 175E Longitude

10 latitude latitude a) 76N 74N 72N 70N b) 76N 74N 72N 70N L a p t e v S e a Lena E 130E 135E 140E 145E 150E L a p t e v S e a Lena Yana longitude Yana 125E 130E 135E 140E 145E 150E longitude Novosibirskie ostrova B.Lyahovskii Is. Novosibirskie ostrova East-Siberian Sea B. Lyahovskii Is. Indigirka East - Siberian Sea Indigirka nm nm Distribution of dissolved methane in the surface layer (a), and bottom layer (b) shows the methane anomalies are associated with the location of fault ones where the sub sea permafrost would degrade (Romanovskii and Hubberten, 2001). That would cause destabilisation of hydrates and methane release into the water and air above (Shakhova et al, 2007ab; Semiletov et al., 2004): see the next slide.

11 Methane in the air 2 m above the sea water along the ship route (September 2005) (Shakhova et al., 2007b)

An effect from destruction of old eroded terrestrial carbon in the near-shore zone of East-Siberian seas

3): up to 2,000-3,000 µatm (the riverine signal is usually ranged by upper limit about 1,000 µatm). A Fig.

12 2. Coastal erosion (Figs.1,2) plays a major role in biogeochemical cycling and sedimentation in the East-Siberian seas. An effect from destruction of old eroded terrestrial carbon in the near-shore zone of East-Siberian seas is significant increase of pco 2 value through the water column (Fig.3): up to 2,000-3,000 µatm (the riverine signal is usually ranged by upper limit about 1,000 µatm). A Fig.1. Rate of coastal erosion may be up to m per summer pco surface bottom Fig.2. The East-Siberian Sea is strongly affected by coastal erosion: CTOM (contribution of terrestrial organic matter) is the largest in the World Ocean (up to 100%) Stations number Fig.3. Oxidation of eroded carbon cause a sharp increase in pco 2 value, ppm pco2 value Semiletov et al., 2007; 2005

13 3. Values of pco 2 decrease from the west (Dm Laptev Strait, ррm) to the east (Long Strait, ррm). Change in flux (F) direction is roughly agreed with position of the frontal Zone (FZ). Then the East-Siberian Sea west of FZ is a source of CO 2, while it is a sink-east of FZ. FZ 2003 Similar changes in CO 2 and F distribution were found in 2004, while mean value of F-emission was one order higher in 2004 in comparison with 2003 (Pipko et al,, TRS, 2005; Semiletov et al., JMS, 2006)

14 An example of quantitative detection of environmental changes in the land-shelf system Table 1. Measured (T, S in the surface layer, wind speed) and calculated values of рсо 2, and СО 2 fluxes between atmosphere and surface of the East-Siberian Sea in September of 2003 and Year, paramete r 2003 г. (n = 41) 2004 г. (n = 54) Т, о С S, U, m s -1 рсо, µatm 2.31 ± ± ± ± ± ± ± ± 130 F СО2, mmol m -2 day ± ± 12.6 During one year (September 2003-September 2004) storage of dissolved CO 2 increased about 30%, which in relation with increase of PM storage (~ 3 х10 6 t ), and decrease in S- storage and DIC-storage, may indicate on increase in transport of eroded carbon and its oxidation. Same time the water became warmer, and fresh water was accumulated in the area of comparison. That environmental changes caused increase in рсо 2, which (+ wind speed increase ~29%) enhanced rate of FСО 2 about 10 times (Pipko et al., 2005). Table 2. Integral values (storage) of dissolved CO 2, DIC, salinity (S), and PM YEARS СО 2, g DIC, g S, g Particulate material, g х х х х х х х х10 12 (Semiletov, Shakhova, Panteleev,GRL, in preparation).

15 CONCLUSIONS 1. Coastal zone acts as an controlling area for production of greenhouse gases and processing of organic matter before the material is transported into the Arctic Ocean. 2. Coastal zone can be source or sink of atmospheric carbon dioxide and methane depending from geological history and water mass dynamics. 3. Coastal erosion plays a major role in biogeochemical cycling and sedimentation in the East-Siberian seas. 4. Offshore permafrost can react to global change and contribute to the climate system energy balance through CH 4 release. The FEBRAS/IARC bi-national research team extends the Arctic Coastal Studies in the International Polar Year (IPY Project #942) by doing the 1 st wintertime expedition on the fast ice in the Laptev Sea (March-April 2007) and along/across the Arctic Eurasian Margin (August-September 2007).

Impact of changing Siberian land-shelf-basin on the Arctic Ocean biogeochemical dynamics

Impact of changing Siberian land-shelf-basin on the Arctic Ocean biogeochemical dynamics PI: Shigeto Nishino (JAMSTEC) Co-PI: Igor Semiletov (IARC/UAF) Other Investigators: Natalia Shakhova (IARC/UAF),