What
this emphatically does is establish that the Orkneys were one degree
warmer during the Medieval Warming period than they are at present.
This is not much of a difference for the latitude involved but
certainly supports the idea not recognized yet that we have in fact
reentered the same part of the climatic cycle.
I
suspect that we have entered the beginning of a four hundred year era
comparable to the MWP and part of a 1200 year cycle that includes
temperature collapses and is driven by deep shifts in the deep and
adjustment of current volumes and location all of which is presently
only hinted at let alone measured. I have found indications of such
a cycle going back at least three such cycles and suspect that the
cycle can be established as real once we figure out how to
investigate it clearly.
It
ultimately stabilizes the Holocene.
A paper published today
in Palaeogeography, Palaeoclimatology, Palaeoecology finds that
the Medieval Warming Period "was warmer than the late 20th
century by ~1°C." The paper adds to the peer-reviewed
publications of over 1000 scientistsshowing that the global Medieval
Warming Period was warmer than the current warming period.
Marine
climatic seasonality during early medieval times (10th to 12th
centuries) based on isotopic records in Viking Age shells from
Orkney, Scotland
MONDAY, JULY 16, 2012
Seasonal sea-surface
temperature (SST) variability during the Medieval Climate Anomaly
(MCA), which corresponds to the height of Viking exploration
(800–1200 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 ± 0.17‰
VSMOW, n = 11) to estimate SST from δ18OSHELL values.
The standard deviation of δ18OWATER values resulted in an error
in SST estimates of ± 0.7 °C. The coldest winter months
recorded in the shells averaged 6.0 ± 0.6 °C and the
warmest summer months averaged 14.1 ± 0.7 °C. Winter
and summer SST during the late 20th century (1961–1990) was
7.77 ± 0.40 °C and 12.42 ± 0.41 °C,
respectively. Thus, during the 10th to 12th centuries winters were
colder and summers were warmer by ~ 2 °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 °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.
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