Hjálmar Hátún

Hjálmar Hátún is a senior research scientist at the Faroe Marine Research Institute (FAMRI) and a lecturer at the University of the Faroe Islands. His research focuses on the large-scale oceanic circulation in the subpolar North Atlantic and its impact on marine ecosystems.

Hjálmar will deliver a plenary talk titled “The North Atlantic subpolar gyre regulates marine ecosystems”.

The subpolar North Atlantic Ocean is characterized by its rich ecosystems – rapid spring blooms, vast energy-rich zooplankton stocks, huge migratory pelagic fish stocks, large seabird colonies and highly productive demersal fish stocks on the shelves surrounding the oceanic basins. Upwelling of nutrients is the most crucial prerequisite for biological productivity, but while this fact is plainly evident at lower latitudes, its importance for the mid-latitudes has been somewhat overlooked in the literature.

The strong atmospheric jet stream, and its associated intense low pressure systems which traverse the subpolar waters, induces cooling and deep water formation and this fuels a huge volume of water with nutrients every winter. This established the oceanographic feature called the subpolar gyre – a large body of cold and low-saline subarctic water, which circulates counterclockwise south of Iceland and Greenland.

Much of Hjálmar’s work revolves around the subpolar gyre, with focus on the northeastern Atlantic. For example, he has illustrated how the size and circulation intensity of this gyre regulates temperature, salinities, nutrient concentrations, the abundance key zooplankton species, stock sizes spawning distribution and feeding migration routes of pelagic fish stocks (blue whiting and mackerel), the breeding success of seabirds and the annual number of pilot whales beached in the Faroe Islands back several centuries.

Hjálmar brings in large-scale indices like the gyre index to collectively discuss key trends in several components of this vast pelagic complex. In addition, he suggests that the adjacent shelf ecosystems should not be studied separately, but rather integrated in a bigger perspective which includes the oceanic waters connecting these shelves. The marked ecosystem variability reverberates in the national economies of small fishery-dependent societies like the Faroe Islands. Studies have furthermore revealed that the temperature of subpolar North Atlantic is one of the most predictable in the World Oceans, which underscores that improving our understanding of the clear bio-physical couplings in these waters might result in socio-economical benefits.

Hjálmar was born in Copenhagen in 1973, but apart from his first two years, was raised in Tórshavn, Faroe Islands. His higher degrees include a Maters study at NTNU in Trondheim, Norway, which included an inspiring year (1998-1999) as an exchange student in theoretical physics at University of Berkeley, California and later a PhD in Physical Oceanography 2001-2003, based at FAMRI, but formally enrolled at the University of Bergen. His thesis defense there became a stepping stone to a Post Doc position at the University of Washington (UW) Seattle in 2004-2005 where he also wrote his highly regarded 2005 Science paper about the North Atlantic subpolar gyre. He has worked as a visiting scholar at the Nansen Center in Bergen (2004) and at the Max Planck Institute in Hamburg (2014). For his work, Dr. Hátún has been honored as an ‘outstanding Faroese young scientist’ (2009) in addition to receiving an “Inspirational Award in Physical Oceanography” from the University of Oslo (NorMER) in 2012.

Currently Dr. Hátún continues his research on the impact of the subpolar gyre on the marine climate and ecosystems, and he is also involved in research on the Atlantic Inflows towards the Arctic and the overflow across the Greenland-Scotland Ridge – a key branch of the ThermoHaline Circulation system.