Monday, February 18, 2013

New paper demonstrates Arctic temperatures are not unusual, unnatural, or unprecedented

A paper published today in Palaeogeography, Palaeoclimatology, Palaeoecology reconstructs Arctic temperatures from shells collected from Iceland and demonstrates that temperatures have been warmer than the present over much of the past 500 years. The paper adds to many other peer-reviewed studies demonstrating that current Arctic temperatures are not unusual, unnatural, or unprecedented. 
Shell growth, a proxy for temperature, has been as high or higher than the present [end of record in the year 2000] during much of the past 500 years. 
Data from a similar study demonstrates that Arctic sea surface temperatures [SSTs] were warmer than the present [year 2000 A.D.] during most of the past 500 years.
 Climate signatures on decadal to interdecadal time scales as obtained from mollusk shells (Arctica islandica) from Iceland

  • a Alfred Wegener Institute for Polar and Marine Research, Bussestr. 24, 27570 Bremerhaven, Germany
  • b Institute of Geosciences, Earth System Science Research Center, University of Mainz, Johann-Joachim-Becher-Weg 21, 55128 Mainz, Germany


Pronounced decadal climate oscillations are detected in a multi-centennial record based on shell growth rates of the marine bivalve mollusk, Arctica islandica, from Iceland. The corresponding analysis of patterns in sea level pressure and temperature exhibit large-scale teleconnections with North Atlantic climate quantities. We find that the record projects onto blocking situations in the northern North Atlantic. The associated circulation shows a low-pressure signature over Greenland and the Labrador Sea and a high-pressure system over Western Europe associated with northeasterly flow towards Iceland and weakening in the westerly zonal flow over Europe. It can be speculated that such circulation affects food availability controlling shell growth. On multidecadal time scales, the record shows a pronounced variability linked to North Atlantic temperature. In our record, we find enhanced variability of the shell growth rates on multidecadal time scales, and it appears that this oscillation has high amplitudes in the 16th to 18th century also consistent with marine alkenone data. It is conceivable that these climate oscillations, also linked to sea ice export and enhanced blocking, are a more pronounced feature during times when the climate was relatively cold.


► We examine the link between climate and shell growth of Arctica islandica. ► The atmospheric circulation shows a blocking pattern for high shell growth. ► Consistent interpretation of Arctica islandica and high-resolution SST ► We find enhanced multidecadal variability in the 16th to 18th century.  Arctica islandicacan be used as a climate archive for the last 500 years.


  1. 5.4. "As discussed in Section 4.4, growth increment chronologies from A.islandica are neither a strong nor a consistent recorder of seawater temperatures and cannot be used to reconstruct them"

    Where in the paper is the quote "Arctica islandica can be used as a climate archive for the last 500 years" ???

  2. Follow the link, it's right there, just below the abstract.

  3. The correlations to "established" temperatures, including the recent 100 years, do not look strong.

    Not sure what you can take from this study about either Arctic or global changes.

    1. There is no "established" instrumental temperature record of the Arctic Ocean over the past 100 years. We only have proxy data, such as this study, to rely upon.