@article {548,
	title = {Seasonal climate change across the Roman Warm Period/Vandal Minimum transition using isotope sclerochronology in archaeological shells and otoliths, southwest Florida, USA},
	journal = {Quaternary International},
	volume = {308},
	year = {2013},
	note = {id: 2298},
	month = {Oct 2},
	pages = {230-241},
	abstract = {Archaeological evidence suggests that southwest Florida experienced variably warmer and wetter climate during the Roman Warm Period (RWP; 300 BC{\textendash}550 AD) relative to the Vandal Minimum (VM; 550{\textendash}800 AD). This hypothesis was tested by reconstructing seasonal-scale climate conditions for the latter part of the RWP (1{\textendash}550 AD) by using high-resolution oxygen isotope ratios (δ18O) of archaeological shells (Mercenaria campechiensis) and otoliths (Ariopsis felis). Eight shells radiocarbon-dated to 150{\textendash}550 AD recorded that the RWP summers at 150{\textendash}250 AD were insignificantly different from today and the RWP summers at 250{\textendash}350 AD and 450{\textendash}550 AD were drier relative to today. Eight otoliths indicate that the winters were variable during the RWP, colder than today at 150{\textendash}200 AD and 250{\textendash}300 AD, similar to today at 200{\textendash}250 AD, 300{\textendash}350 AD and 450{\textendash}500 AD, and warmer than today at 500{\textendash}550 AD. The climate reconstructions agree with archaeological observations and are partially coherent with the history of sea-level change, with a drying and cooling trend at the 95\% confidence level across the RWP/VM transition. The climate transition is not only consistent with falling sea level, but also coherent with reduced solar radiation. Reduced solar radiation may have triggered a change in atmospheric circulation patterns that precipitated the observed climate transition.},
	issn = {1040-6182},
	doi = {10.1016/j.quaint.2012.11.013},
	author = {Wang, Ting and Surge, Donna and Walker, Karen Jo}
}
@article {128,
	title = {Marine climatic seasonality during medieval times (10th to 12th centuries) based on isotopic records in Viking Age shells from Orkney, Scotland},
	journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
	volume = {350{\textendash}352},
	year = {2012},
	note = {id: 2320},
	pages = {236-246},
	abstract = {Seasonal sea-surface temperature (SST) variability during the Medieval Climate Anomaly (MCA), which corresponds to the height of Viking exploration (800{\textendash}1200 AD), was estimated using oxygen isotope ratios (δ18O) obtained from high-resolution samples micromilled from archaeological shells of the European limpet, Patella vulgata. Our findings illustrate the advantage of targeting SST archives from fast-growing, short-lived molluscs that capture summer and winter seasons simultaneously. Shells from the 10th to 12th centuries (early MCA) were collected from well-stratified horizons, which accumulated in Viking shell and fish middens at Quoygrew on Westray in the archipelago of Orkney, Scotland. Their ages were constrained based on artifacts and radiocarbon dating of bone, charred cereal grain, and the shells used in this study. We used measured δ18OWATER values taken from nearby Rack Wick Bay (average 0.31 {\textpm} 0.17{\textperthousand} VSMOW, n = 11) to estimate SST from δ18OSHELL values. The standard deviation of δ18OWATER values resulted in an error in SST estimates of {\textpm} 0.7 {\textdegree}C. The coldest winter months recorded in the shells averaged 6.0 {\textpm} 0.6 {\textdegree}C and the warmest summer months averaged 14.1 {\textpm} 0.7 {\textdegree}C. Winter and summer SST during the late 20th century (1961{\textendash}1990) was 7.77 {\textpm} 0.40 {\textdegree}C and 12.42 {\textpm} 0.41 {\textdegree}C, respectively. Thus, during the 10th to 12th centuries winters were colder and summers were warmer by ~ 2 {\textdegree}C and seasonality was higher relative to the late 20th century. Without the benefit of seasonal resolution, SST averaged from shell time series would be weighted toward the fast-growing summer season, resulting in the conclusion that the early MCA was warmer than the late 20th century by ~ 1 {\textdegree}C. This conclusion is broadly true for the summer season, but not true for the winter season. Higher seasonality and cooler winters during early medieval times may result from a weakened North Atlantic Oscillation index.},
	issn = {0031-0182},
	doi = {10.1016/j.palaeo.2012.07.003},
	url = {http://www.sciencedirect.com/science/article/pii/S0031018212003926},
	author = {Surge, Donna and Barrett, James H.}
}
