High Resolution Ice Core Records of Late Holocene Volcanism: Current and Future Contributions from the Greenland PARCA Cores

A suite of spatially distributed, multi-century cores collected since 1995 under NASA's Program for Arctic Regional Climate Assessment (PARCA) provides an excellent archive of volcanic emissions reaching Greenland. As records of equiv­ alent quality from higher accumulation sites in Antarctica become available, their integration will produce a richer, better temporally constrained and more climatologically valuable history of global volcanism. The Greenland PARCA cores have been accurately dated using multiple seasonally varying indicators ( 8 1 8 0 , insoluble dust, H 2 0 2 , nitrate, calcium) and the ongoing chemical analyses are pro­ viding new volcanic histories that complement the limited records that exist. The first results confirm that the sulfate aerosols from an unidentified pre-Tambora eruption called Unknown: (1) were widely dispersed across the Greenland ice sheet; (2) first arrived in the 1810 A.D. snow fall; and, (3) in 1810 A.D. , the first year after the eruption (1809 A.D.) , produced concentrations of excess S 0 4 2 " (EXS) comparable to those deposited in 1816 A.D. , the first year after the erup­ tion of Tambora in 1815 A.D. The EXS originating from the eruption of Laki craters or Lakagigar (1783 A.D.) is confined to a single year (1783 A.D.) and varies considerably across the ice sheet, primarily as a function of the local accu­ mulation rate. Future chemical analyses of the PARCA cores promise richly detailed histories of EXS emissions from both known and yet to be identified vol­ canic eruptions. The high temporal resolution of these ice core records will help resolve timing issues and their broad spatial distribution will provide a more rep­ resentative estimate of the EXS flux associated with a specific eruption.