JPB wrote:
And one theory of what caused the "little ice age" was a rapid warming period directly preceding it which added large quantities of fresh water from melting glaciers to the oceans (similar to what we are seeing now). Enough fresh water was added from the glaciers that the salinity of the oceans changed, preventing the thermal layers from following their normal paths. The Gulf Stream is one part of a vast thermal current which affects the atmosphere of coastal areas. It is thought that Greenland was once lush pasture that became barren only after the little ice age and that the climate there became so much colder because the waters were no longer warmed by the thermal currents. The Inuits survived because of their dependency on cold-water fish. The Vikings perished because of their dependency on agriculture and warm-water cod.
That may be "one theory" but I doubt that anyone with a scientific background takes it seriously.
In the first place there is no data to support the glacier melting hypothesis in the "rapid warming period directly preceding it". No records of past ocean currents exist, and even the models we use today to "predict" changes in them don't work because of the non-linearity and complexity of the factors involved -- sensitive dependence and chaos. (We can't even predict the next appearance of the El Ninho current in the southern Pacific, though we know empirically that its cycle varies from 8 to 20 years in length.)
The fact is that the so called "little Ice age correlates very well with an unusual minimum in the observed activity of solar flares (the Maunder Minimum). In addition the complex relationship of the periodic variations in the inclination of the earth's axis to the ecliptic plane with those of the major & minor axes of the earth's orbit also yielded less exposure to solar radiation during that period. Both factors are supported by real data and are likely to have been sufficient to have caused the cooling --- and very likely the warm period that preceeded it.
No one has suggested that Greenland was "covered with lush pastures". However known parts of it certainly were and are even pastureland today. The old Norse settlement at Scoresbysund on Greenland's East coast (which is still inhabited today) has yielded substantial evidence of the animal husbandry of the early Norse settlers and even some of the primitive agriculture they practiced. The subsequent cooling reduced the pastureland available to them; eliminated the agriculture and probably led to the abandonment of the settlement.
The key point which you apparently missed is that the "period of rapid warming directly preceding it", the Little Ice Age itself, and the subsequent warming all occurred without any anthromorphic input. Given that the bland assumption, so credulously accepted by the AGW cultists, that manmade factors MUST certainly be behind the contemporary observed warming - and that all other known historical factors MUST be absent - is palpably laughable.
