Freshwater from Siberia revealed in the hotspot for climate change

Sequestration of 10 percent of the total carbon delivered to the Arctic by rivers

The researchers used high-resolution, in situ observations of dissolved organic matter (DOM) fluorescence to trace the pathway of freshwater and carbon from Arctic rivers.

Similar to how tea leaves color tea, DOM gives seawater a distinct hue. Different Arctic freshwater sources carry slightly different DOM fingerprints, allowing scientists to trace the water back to its origin and determine the source of Arctic freshwater.

The researchers estimate that the pathway from Siberian Arctic rivers to the deep waters of the Labrador Sea, southwest of Greenland sequesters approximately 2 teragrams (Tg) of carbon annually – this equals about 10 percent of the total carbon delivered to the Arctic by rivers making it a non-negligible carbon sink.

New method with promising prospects

By using an in-situ DOM fluorometer, the team was able to measure the DOM signal directly in the water, providing a simple yet effective way to obtain high-resolution data for tracking the pathway and fate of Arctic freshwater and carbon. 

Using this new approach, the researchers traced freshwater and carbon from Siberian Arctic rivers into the deep ocean waters of the Labrador Sea., southeast of Geenland.

These deep waters are a part of the Atlantic Meridional Overturning Circulation, AMOC, a large-scale system of ocean currents that plays a key role in regulating Earth’s climate. 

Understanding the impact of Arctic freshwater on the AMOC is a priority, as there is growing concern that increased freshwater input could destabilize crucial ocean currents in the North Atlantic.

The study highlights the potential of this new method for tracking Arctic freshwater and carbon, which could prove essential for monitoring future climate change. 

Losing the Polar characteristics

The researchers suggest that incorporating the method onto other observation platforms, such as moorings, gliders, and floats, could help clarify the fate of Arctic freshwater - essentially where does the freshwater go? - and further our understanding of Arctic freshwater impacts on the AMOC.

The scientific paper is part of a new PhD thesis by Caroline Gjelstrup from DTU Aqua with the title Changing oceanographic conditions in East Greenland.

According to Caroline’s publications the waters east of Greenland are experiencing a phenomenon referred to as Atlantification, which means they are losing their Polar characteristics. 

East Greenland is a looking glass for climate change

The PhD thesis investigates changing oceanographic conditions in the ocean waters east of Greenland, which can be considered a transition zone between Arctic and Atlantic conditions characterized by largescale connectivity as demonstrated in the science paper.

There is an expansion of Atlantic-type conditions at the expense of typical Arctic waters with temperatures close to freezing, lower salinities, and conditions favorable for sea ice.

The hydrographic changes that Caroline Gjelstrup has been studying suggest that East Greenland has become a looking glass for climate change, acting both as a recipient and a source of globally relevant change.

Please contact us to see the PhD Changing oceanographic conditions in East Greenland.