Carbon concentration and sinking velocity of particles measured during the James Cook cruise JC087, March 2013

Sinking organic particles were collected from the Porcupine Abyssal Plain in 2013. Collection was done using a marine snow catcher (MSC), which is essentially a large (95 L) settling column. The marine snow catcher is deployed to one depth, the water trapped inside and then brought to the surface and left to stand on deck for 2 hours during which time the particles settle down (or up) the MSC depending on their settling rate. The particles are then collected and due to position of collection from the snow catcher are determined as fast or slow sinking particles. Some fluxes are negative as they were positively buoyant and not sinking.

Total organic carbon, delta13C, biomarker, diatom distributions in sediment core JM11-FI-19PC

In the light of rapidly diminishing sea ice cover in the Arctic during the present atmospheric warming, it is imperative to study the distribution of sea ice in the past in relation to rapid climate change. Here we focus on glacial millennial scale climatic events (Dansgaard/Oeschger events) using the new sea ice proxy IP25 in combination with phytoplankton proxy data and quantification of diatom species in a record from the SE Norwegian Sea. We demonstrate that expansion and retreat of sea ice varied consistently in pace with the rapid climate changes 90 ka to present, and with this present the first IP25 sea ice proxy record resolving the D/O cyclicity going back in time into Marine Isotope Stage 5a. Sea ice retreated abruptly at the start of warm interstadials, but spread rapidly during the cooling phase of the interstadials and became near-perennial and perennial during cold stadials and Heinrich events, respectively. Low salinity surface water and the sea ice edge spread to the Greenland-Scotland Ridge, and during the largest Heinrich events, probably far into the Atlantic Ocean.