What was done
The authors used an infra-red stimulated luminescence technique to date sands from dunes in the Aquitaine region of southwest France.

What was learned
There were three main phases of dune formation.  Phase I (4000 to 3000 years ago) occurred during the long cold interval that preceded the Roman Warm Period.  Phase II (1300 to 900 years ago) occurred during the early to middle Medieval Warm Period, but during what the authors describe as its "cooler periods."  Phase III (550 to 250 years ago) occurred during the Little Ice Age, again during what the authors call its cooler periods.  In addition, in a mini-review of the literature the authors describe similar massive wind-induced movements of sand in England, Scotland, Denmark, Portugal and The Netherlands.

Dune formation on the southwest coast of France has generally been most common during cooler climatic intervals.  In the most recent of these periods, there is voluminous historical evidence of many severe North Atlantic wind storms.  The authors note that the southward spread of sea ice and polar water at this time likely created "an increased thermal gradient between 50°N and 65°N which intensified storm activity in the North Atlantic ... which may well have mobilized sand inland from the coast."  In addition, they note that sand-drift episodes across Europe "show synchroneity with sand invasion in the Aquitaine region of southwest France, implying a regional response to increased storminess."

What it means
When one reads accounts of the adverse consequences of the fierce storms that occurred during the Little Ice Age, one wonders why any of the inhabitants of Europe would be concerned about the past century's increase in temperature that has likely rescued them from the continuation of such destructive weather.