Wednesday, 29 February 2012

Roman Warming Period In Eastern Mediterranean Warmer Than Modern Warming

Short term climate variability during “Roman Classical Period” in the eastern Mediterranean
Quaternary Science Reviews, Volume 30, Issues 27–28, December 2011, Pages 3880-3891
Liang Chen, Karin A.F. Zonneveld, Gerard J.M. Versteegh


To obtain insight into character and potential forcing of short-term climatic and oceanographic variability in the southern Italian region during the “Roman Classical Period” (60 BC–AD 200), climatic and environmental reconstructions based on a dinoflagelate cyst record from a well dated site in the Gulf of Taranto located at the distal end of the Po-river discharge plume have been established with high temporal resolution. Short-term fluctuations in accumulation rates of the Adriatic Surface Water species Lingulodinium machaerophorum, the freshwater algae Concentricystes and species resistant to aerobic degradation indicate that fluctuations in the trophic state of the upper waters are related to river discharge of northern and eastern Italian rivers which in turn are strongly related to precipitation in Italy.
 The dinoflagellate cyst association indicates that local sea surface temperatures which in this region are strongly linked to local air temperatures were slightly higher than today. We reconstruct that sea surface temperatures have been relatively high and stable between 60 BC–AD 90 and show a decreasing trend after AD 90. Fluctuations in temperature and river discharge rates have a strong cyclic character with main cyclicities of 7–8 and 11 years. We argue that these cycles are related to variations of the North Atlantic Oscillation climate mode. A strong correlation is observed with global variation in Δ14C anomalies suggesting that solar variability might be one of the major forcings of the regional climate. Apart from cyclic climate variability we observed a good correlation between non-cyclic temperature drops and global volcanic activity indicating that the latter forms an additional major forcing factor of the southern Italian climate during the Roman Classical Period.

From CO2 Science 

What it means
With respect to the southern region of Italy, it would appear that the relatively high temperatures of today are not unique. In fact, they may well be somewhat lower than those that prevailed there during the Roman Warm Period. And these findings suggest that the non-unique warmth of our day need not be attributed to a unique phenomenon, such as the historical increase in the atmosphere's CO2 concentration that has resulted from mankind's burning of fossil fuels.