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Late-Holocene Sea Surface Temperatures of the North Icelandic Shelf
Jiang, H., Seidenkrantz, M-S., Knudsen, K.L. and Eiriksson, J. 2002. Late-Holocene summer sea-surface temperatures based on a diatom record from the north Icelandic shelf. The Holocene 12: 137-147.

What was done
Diatom assemblages from a high-resolution core extracted from the seabed of the north Icelandic shelf (6630.09'N, 1904.34'W) were used to reconstruct a 4600-year history of mean summer sea surface temperature at that location.

What was learned
The warmest temperature of the record (~8.1C) occurred near its beginning at about 4400 years before present (BP). Thereafter, the climate cooled, fitfully over the next 1700 years, but more consistently over the final 2700 years. In fact, most of the data of this final period are well described by a steadily declining linear relationship. There is one data point at about 1500 years BP that rises above this line by approximately 0.5C and another at about 1350 years BP that falls below the line by approximately 0.5C. The most dramatic departure, however, is centered on about 850 years BP, when the temperature rises by more than 1C above the line describing the long-term downward trend. Last of all, the most recent data point has a value of approximately 6.3C.

What it means
The past 2700 years have witnessed a significant deterioration of the climate in the vicinity of the north Icelandic shelf, as the earth has moved ever further away from the benign weather of the Roman Warm Period. After the planet's descent into the Dark Ages Cool Period, however, the Icelandic record depicts a nearly complete recovery during the middle of the Medieval Warm Period; but this "Little Climatic Optimum" soon gave way to the rapid cooling that produced the Little Ice Age, which brought mean summer sea surface temperatures down by about 2.2C from what they were at the peak of the Medieval Warm Period.

Clearly, it's time for a little warmth again; and the results of this study bear record of the fact that the region around Iceland is going to need a whole lot of it to return to its former "glory days" of both the Medieval Warm Period and the earlier Roman Warm Period.

Reviewed 26 June 2002