Climate-Cryosphere-Carbon cruise 2014

Climate-Cryosphere-Carbon cruise 2014

Top image: Oden in Barrow, Alaska where the rotation of crew and science party took place. Photo: Riko Noormets/UNIS.

On 4 July, a large international expedition of scientists including UNIS students and staff set sail from Tromsø towards the East Siberian Arctic Ocean. The expedition, expected back in Tromsø this coming weekend, is part of a Swedish-Russian-US collaborative research program to study the linkages between Climate, Cryosphere and Carbon cycle.

2 October 2014
Text and photos: Riko Noormets and SWERUS-C3 Programme

The three months long expedition on the Swedish icebreaker ODEN is part of Swedish-Russian-US collaborative research program SWERUS-C3 to study the linkages between Climate, Cryosphere and Carbon cycle.

The objectives of the SWERUS-C3 research program is to quantitatively study the key climate change processes in the Arctic Ocean, such as methane release from subsea permafrost and gas hydrates, fate of carbon released from the thawing submerged and coastal permafrost, and the recent (postglacial) history of sea ice and its role in the in the carbon fluxes.

The East Siberian Arctic Ocean (ESAO) is the target area because it is experiencing the fastest rates of climate warming and because it stores vast amount of vulnerable carbon. The ESAO is sparingly explored despite hosting 80% of the world’s subsea permafrost with large amounts of carbon currently stored in the shelf and slope sediments and in its coastal Yedoma permafrost.

From permafrost thawing to the venting of greenhouse gases
Expedition to the East Siberian Arctic Seas on the I/B ODEN is divided into two 1.5 months legs with the rotation of crew and scientists in Barrow, Alaska.

Cruise track of SWERUS-C3 expedition

Cruise track of SWERUS-C3 expedition (http://oden.geo.su.se/map/).

The first leg had the main theme “From permafrost thawing to the venting of greenhouse gases”. The target area was the vast, poorly explored yet critical region for marine permafrost-carbon-climate interactions on the outer ESAO shelf and upper slope.

Riko Noormets from UNIS was leading the Work Package (WP) H: “Geophysical seafloor mapping” and Pete Hill (Stockholm University/UNIS master student) was involved in WP E: “Sediment collection and Processing”. Pete’s videos taken with a GoPro camera attached to the multicorer leg featuring the water column filled with gas bubbles have already received abundant attention worldwide.

Methane bubbles rising from the seafloor in the Laptev Sea.

Methane bubbles rising from the seafloor to the surface in the Laptev Sea. Photo: SWERUS-C3, Pete Hill

Geophysical seafloor mapping was done using ODEN’s hull-mounted echosounders and also from RV Skidbladner – a 6.4 m boat equipped with a mobile multibeam echosounder system and subbottom profiler. Using a small boat in the Arctic Ocean required, of course, calm weather and sea ice-free conditions but doubled our capacity for seafloor mapping.

Methane flares
The second leg, currently on its way back from the Arctic Ocean to arrive in Tromsø 4. October, is coordinated by Martin Jakobsson (Stockholm University/UNIS) and has the main theme “From warming seawater and shrinking sea ice to venting of greenhouse gases”.

This leg involves coring of high-resolution post-glacial sediment archives in Herald Canyon, mapping of gas hydrates, oceanographic investigations and sea water sampling along the continental slope of the East Siberian Sea. Several participants of this leg are involved as guest lecturers at UNIS marine geology courses and will bring the new exciting knowledge to UNIS students in the coming years.

Screenshot of EK60 ‘fish finder’ echosounder shows extremely high gas bubble concentration

Screenshot of EK60 ‘fish finder’ echosounder showing extremely high gas bubble concentration in the water column (red areas).

The unique geological, geophysical, sediment and water column biogeochemical, atmospheric and oceanographic data collected during the expedition includes the evidence of most spectacular methane flares in the water column reaching from the seafloor to the surface.

We also found morphological evidence of the former sea- and glacier ice traces on the seafloor, atmospheric and seawater chemistry measurements and sediment cores that will be analysed for a number of parameters in order to study the modern as well as paleo-processes related to climate-cryosphere-carbon interactions in the Arctic.

3D image of a methane seep site (blue-purple colours).

3D image of a methane seep site imaged with the EM122 multibeam echosounder (blue-purple colours denoting the gas in the water column. Seabed is imaged in copper colours). Visualization: Denis Chernykh/SWERUS-C3

A frequently updated cruise track, blogs and many more images and videos can be seen on the SWERUS-C3 website: http://swerus-c3.geo.su.se/

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