Nitrate concentrations in Greenland ice have almost doubled since the onset of the Industrial Revolution

Nature Reports Climate Change, published online 11 June 2009; doi: 10.1038/climate.2009.55

Abnormal nitrogen

by Alicia Newton, Science 324, 5932 (2009)

MEREDITH HASTINGS

Nitrate concentrations in Greenland ice have almost doubled since the onset of the Industrial Revolution, according to scientists. The rise in nitrate is accompanied by a sharp drop in the isotopic signature of the nitrogen, beginning just as humans started pumping nitrogen oxides into the atmosphere.

Meredith Hastings of Brown University and colleagues used a 100-metre-long ice core from Summit, Greenland, to track changes in nitrogen composition over the past three centuries. Beginning in 1850, the isotopic ratio of the nitrogen, which in part reflects the source of the nitrate, began to decline, just as greenhouse gas concentrations were starting to rise in response to the widespread burning of fossil fuels. The sharpest jump in the isotopic ratio came between 1950 and 1980, when emissions also soared. This overall trend would be difficult to explain through changing chemical processes in the snow or atmosphere alone, leaving fossil fuel combustion as the most likely driver.

Nitrogen oxides are among the six greenhouse gases regulated under the Kyoto Protocol. The team hopes that further work will allow them to determine how changes in climate influence natural nitrogen oxide sources.

Link:  http://www.nature.com/climate/2009/0907/full/climate.2009.55.html