Holocene climatic variability was studied in a 9500-year lake-sediment sequence from the Abisko region in Swedish Lapland, using the oxygen-isotope ratio in diatom biogenic silica (␦ 18 O si ). Oxygen-and hydrogen-isotope ratios of waters from the Abisko area suggest that in this region the evaporative flux is small and the isotopic composition of most lakes reflects that of the local precipitation. The hydrological setting of the region and sensitivity analysis of isotopic response to changing climatic parameters such as humidity, inflow and evaporation show that the downcore diatom ␦ 18 O si record is primarily controlled by changes in the summer isotopic composition of the lake water. The overall 3.5‰ depletion in ␦ 18 O si since the early Holocene is interpreted as an increase in the influence of the Arctic polar continental air mass that carries depleted precipitation. We estimate that this change is associated with a 2.5-4°C cooling that has occurred since the early Holocene. In general, the diatom ␦ 18 O si record resembles the average annual air temperature reconstructed for the Greenland ice core GISP2, especially during the past 4000 years, with a pronounced cooling starting at 2000 years BP.

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The last interglacial period (127-110 kyr ago) has been considered to be an analogue to the present interglacial period, the Holocene, which may help us to understand present climate evolution. But whereas Holocene climate has been essentially stable in Europe, variability in climate during the last interglacial period has remained unresolved, because climate reconstructions from ice cores, continental records and marine sediment cores give conflicting results for this period. Here we present a high-resolution multi-proxy lacustrine record of climate change during the last interglacial period, based on oxygen isotopes in diatom silica, diatom assemblages and pollen-climate transfer functions from the Ribains maar in France. Contrary to a previous study, our data do not show a cold event interrupting the warm interglacial climate. Instead, we find an early temperature maximum with a transition to a colder climate about halfway through the sequence. The end of the interglacial period is clearly marked by an abrupt change in all proxy records. Our study confirms that in southwestern Europe the last interglacial period was a time of climatic stability and is therefore still likely to represent a useful analogue for the present climate.

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