A medium-length ice core was drilled at the ice divide on the Lomonosovfonna plateau (1230 m a.s.l.), Svalbard, in May 1997. As part of this project, temperature measurements were performed in the 120m deep borehole. At this site the ice thickness based on radar measurements is 126.5 m and the mean annual accumulation rate is 380 kg m–3. the measurements over the 15–120m depth interval show a nearly isothermal profile with a mean value of –2.8˚C and a standard deviation of 0.2˚C. the measurements reveal a temperature minimum at approximately 70m depth and a temperature gradient of 0.011 ±0.004˚Cm–1 near the bottom. the temperature minimum and relatively low temperature gradient cannot be explained in terms of a steady-state climate. Numerical calculations with a simple one-dimensional diffusion–advection model show that the temperature increased at a maximum rate of 0.02–0.025Ka–1 over the last 100 years, the total temperature increase amounting to 2.0–3.0K. Forcing the model with the observed record at Svalbard airport revealed that in the 19th century the surface temperature was at most 2.5 K lower, and that the instrumental observations started during a period with temperatures comparable to the end of the 19th century. the data are of particular interest for historical simulations since often no other temperature data are available in polar areas.

In 1997 a 121 m ice core was retrieved from Lomonosovfonna, the highest ice field in Spitsbergen, Svalbard (1250 m a.s.l.). Radar measurements indicate an ice depth of 126.5 m, and borehole temperature measurements show that the ice is below the melting point. High-resolution sampling of major ions, oxygen isotopes and deuterium has been performed on the core, and the results from the uppermost 36 m suggest that quasi-annual signals are preserved. The 1963 radioactive layer is situated at 18.5–18.95 m, giving a mean annual accumulation of 0.36 m w.e. for the period 1963–96. The upper 36 m of the ice core was dated back to 1920 by counting layers provided by the seasonal variations of the ions in addition to using a constant accumulation rate, with thinning by pure shear according to Nye (1963). The stratigraphy does not seem to have been obliterated by meltwater percolation, in contrast to most previous core sites on Svalbard. The anthropogenic influence on the Svalbard environment is illustrated by increased levels of sulphate, nitrate and acidity. Both nitrate and sulphate levels started to increase in the late 1940s, remained high until the late 1980s and have decreased during the last 15 years. The records of δ 18O, MSA (methane-sulphonic acid), and melt features along the core agree with the temperature record from Longyearbyen and the sea-ice record from the Barents Sea at a multi-year resolution, suggesting that this ice core reflects local climatic conditions.