Ice-core sulfate from three northern hemisphere sites: Source and temperature forcing implications

Comparison of ice-core nss sulfate records (two sites in Greenland and one in the North Pacific) with temperature change records for the regions including these core sites provides further confirmation that change in the concentration of anthropogenic sulfate has had a significant effect on regional temperature during at least the period ∼ad1940–1970 over at least the Atlantic portion of the Arctic. Using the ad1880–1985 portion of our ice-core records as an analog, we provide a test of the potential temperature depression caused by non-seasalt (nss) sulfate aerosols over Greenland during the period ∼ad700–1900 concluding that the anthropogenic era is unique by comparison. Statistical examination of this record allows a determination of the relative contributions of volcanic vs biogenic source nss sulfate during this period plus a characterization of the variability in these two sources.