Glacier acceleration through subsurface ocean warming

The sudden acceleration in 1997 of Jakobshavn Isbræ, one of Greenland’s largest outlet glaciers, was caused by subsurface ocean warming, according to research. The study suggests that ocean temperatures may be more important for glacier flow than previously thought. The prediction of future rapid dynamic responses of other outlet glaciers to climate change may therefore require detailed knowledge of regional ocean dynamics.

David Holland and colleagues present hydrographic data that show a sudden increase in subsurface ocean temperature in 1997 along the entire west coast of Greenland. The arrival of relatively warm water that originated from the Irminger Sea near Iceland could therefore have triggered the increase in the glacier speed. The authors trace these oceanic changes back to changes in the atmospheric circulation in the North Atlantic region.

Author contact:
David Holland (New York University, NY, USA)
Tel: +1 212 998 3245; E-mail: holland@cims.nyu.edu

Coastal pollution could produce an unhealthy chemical cocktail

The reaction of chemical compounds in the pollution from cities and ships with sea salt aerosols from the ocean could affect air quality in coastal areas where the two meet, according to a research. A team measured high levels of nitryl chloride, an active halogen implicated in ground-level ozone production, in industrially polluted air along the southeast coast of the US, implying that ozone pollution could be particularly high where industrial combustion products meet the ocean, as in many megacities around the world.

James Roberts and colleagues measured unexpectedly high levels of nitryl chloride in ship exhaust plumes along the southeast coast of the US. They show that this chemical compound is produced during the night by the reaction of the nitrogen oxides in polluted air from ships or cities with the chlorine from sea salt. With the help of the morning sunlight, nitryl oxide is rapidly split into a reactive radical that can produce ozone in combination with suitable atmospheric compounds, and nitrogen oxides. (researchsea)
Author contact:

James Roberts (National Oceanic and Atmospheric Administration, Boulder, CO, USA)
Tel: +1 303 497 3982, E-mail: James.M.Roberts@noaa.gov