2000 Years of Climate Variablity from Arctic Lakes



Proxy climate indicators

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Synthesis and data-model comparison

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Synthesis and data-model comparison


The temperature history of the first millennium C.E. is sparsely documented, especially in the Arctic. We present a synthesis of decadally resolved proxy temperature records from poleward of 60°N covering the past 2000 years, which indicates that a pervasive cooling in progress 2000 years ago continued through the Middle ages and into the Little Ice Age. A 2000-year transient climate simulation with the Community Climate System Model shows the same temperature sensitivity to changes in insolation as does our proxy reconstruction, supporting the inference that this long-term trend was caused by the steady orbitally driven reduction in summer insolation. The cooling trend was reversed during the 20th century, with four of the five warmest decades of our 2000-year-long reconstruction occurring between 1950 and 2000.

The long-term cooling trend in the Arctic was reversed during recent decades. The blue line shows the estimated Arctic average summer temperature over the last 2000 years, based on proxy records from lake sediments, ice cores, and tree rings. The shaded area represents variability among the 23 sites use for the reconstruction. The red line shows the recent warming based on instrumental temperatures. From Kaufman et al. (2009).


  • Donwload spreadsheet (excel) of 10-year average summer temperature reconstruction from 23 proxy records (February 5, 2010 version)
  • This synthesis includes all available proxy records (as of 2/10) that are (1) located north of 60°N latitude, (2) extended back to at least 1000 AD, (3) resolved at annual to decadal level, (4) published with data available publicly, and (5) shown to be sensitive to temperature. As new records that meet these criteria come available, or if any were inadvertently left out of this synthesis, please forward them so that they can be integrated into the next composite record.