The fjords outside two of Greenland’s largest outlet glaciers - which shed ice from the ice sheet into the ocean - experience variations in heat content and other water properties every 3 to 10 days between September and May. These findings, reported online in Nature Geoscience, suggest that during the non-summer months, warm waters in the fjord are renewed regularly and effectively from the ocean, which may affect glacier melt rate.

Rebecca Jackson and colleagues analysed continuous September-to-May records of water properties and velocity from Sermilik and Kangerdlugssuaq fjords, which drain the fifth and third largest outlets of the Greenland ice sheet, respectively. They report velocity pulses associated with fluctuations in temperature and salinity that typically last a few days, similar to the timescale of passing weather systems. The authors suggest that these findings show that water from the surrounding ocean is regularly pumped into the fjords in the non-summer months.