Soot in the Arctic

Substantial concentrations of graphitic carbon and its associated large optical absorption coefficient are observed in the Arctic. The graphitic content shows a dramatic increase from late fall to early spring, reaching levels that are comparable to those found in urban environments (i.e., the peak values in February are only about a factor of 10 less than the average levels found in New York City and a factor of three less than those found in Berkeley, California, and Denver, Colorado). If one ignores the possible contribution of natural burning processes which are expected to be small during this time of the year in the northern hemisphere, this graphitic component can be attributed directly to anthropogenic activity.