What graphs are you seeing? This is what the article says:
> Radiocarbon dating suggests the ridges [farming furrows or similar] were initially constructed roughly 1,000 years ago. They were maintained and used for 600 years after that.
Wikipedia says this:
> Erik Thorvaldsson (c. 950 – c. 1003), known as Erik the Red, was a Norse explorer [...]
> Around the year of 982, Erik was exiled from Iceland for three years, during which time he explored Greenland, eventually culminating in his founding of the first successful European settlement on the island. Erik would later die there around 1003 CE
["Erik the Red"]
And this:
> The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region.
> The period has been conventionally defined as extending from the 16th to the 19th centuries
> The NASA Earth Observatory notes three particularly cold intervals. One began about 1650, another about 1770, and the last in 1850
["Little Ice Age"]
And this:
> The Medieval Warm Period (MWP), also known as the Medieval Climate Optimum or the Medieval Climatic Anomaly, was a time of warm climate in the North Atlantic region that lasted from about 950 CE to about 1250 CE.
["Medieval Warm Period"]
The article would appear to suggest that the farm was established near the beginning of the Medieval Warm Period and abandoned near the beginning of the Little Ice Age... which seems incredibly unsurprising.
> They would have been farming here during a cool period.
I see no indication of that.