Deuterium excess record from a small Arctic ice cap

n this paper we present a deuterium excess (d) record from an ice core drilled on a

small ice cap in Svalbard in 1997. The core site is located at Lomonosovfonna at 1255 m

asl, and the analyzed time series spans the period 1400–1990 A.D. The record shows

pronounced multidecadal to centennial-scale variations coherent with sea surface

temperature changes registered in the subtropical to southern middle-latitude North

Atlantic during the instrumental period. We interpret the negative trend in the deuterium

excess during the 1400s and 1500s as an indication of cooling in the North Atlantic

associated with the onset of the Little Ice Age. Consistently positive anomalies of d after

1900, peaking at about 1950, correspond with well-documented contemporary warming.

Yet the maximum values of deuterium excess during 1900–1990 are not as high as in

the early part of the record (pre-1550). This suggests that the sea surface temperatures

during this earlier period of time in the North Atlantic to the south of approximately

45°N were at least comparable with those registered in the 20th century before the end of

the 1980s. We examine the potential for a cold bias to exist in the deuterium excess

record due to increased evaporation from the local colder sources of moisture having

isotopically cold signature. It is argued that despite a recent oceanic warming, the

contribution from this local moisture to the Lomonosovfonna precipitation budget is still

insufficient to interfere with the isotopic signal from the primary moisture region in the

midlatitude North Atlantic